Slide 1

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 2

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 3

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 4

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 5

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 6

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 7

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 8

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 9

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 10

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 11

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 12

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 13

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 14

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 15

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 16

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 17

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 18

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 19

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 20

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 21

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 22

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 23

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 24

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 25

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 26

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 27

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 28

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 29

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 30

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 31

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 32

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 33

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 34

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 35

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 36

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 37

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 38

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?


Slide 39

Aim

To introduce the Concept and Fundamentals of
Visual Navigation

Objectives
1. Define “Visual Navigation and Dead Reckoning
Navigation”
2. Describe the “Form of the Earth”
3. Identity our position, the direction we wish to
travel and the distance we want to fly
4. Describe and calculate our air speed and velocity
through the air
5. Calculate and describe our altitude above the
surface of the Earth

1. Definitions
Visual Navigation is fun, challenging and very
satisfying if done properly.
Australia can be characterised as follows
• A sparse population with our capital and other major cities
concentrated along the coast, principally in the eastern states
• Many towns on charts are very small
and easy to confuse with other towns
• A lack once away from the coast of
easily recognisable land features due
to the generally flat terrain and lack
of trees, vegetation, rivers or other
easily distinguishable features
especially as you move further inland
• There are few Navigation Aids such as
a VOR or NDB as you move further
inland

1. Definitions
How to successfully navigate your way around
Australia
1. Understand the concepts and principles involved in Visual Navigation
2. Plan your flight carefully before you depart
3. Be organised and disciplined in your approach in flight to navigating
from your take off point to your destination
4. Be “ahead of the aircraft” by which we mean anticipating what
needs to be done in the next few minutes and calculating
contingencies to cope with unexpected events

1. Definitions
Visual Navigation
Visual Navigation is where pilots use aviation charts (maps) to match
observed ground features to determine the position (fix) of the aircraft
Visual Navigation is based on a pilot:
• Being able to sight sufficient ground features be able to fix the
position of the aircraft at not less then 30 minute intervals
• Navigation Aids such as a GPS, VOR,
NDB may be used to assist in
determining the position of the aircraft
but the prime means of navigating is
by Dead Reckoning

1. Definitions
Dead Reckoning
Dead Reckoning (DR) is the process of calculating one's current position
by using a previously determined position, or fix and advancing that
position based upon known or estimated speeds over elapsed time
Dead Reckoning is based on a pilot:
• Flying accurately the Headings (HDG) which have been previously
calculated
• Knowing the elapsed time flown since the last known position
• Being able to closely estimate the achieved Ground Speed (GS)
• Accurate chart (map) reading to initially identify your position based
on time elapsed and then confirming your position by reference to
ground features

2. Form of the Earth
Shape and Movement
The Earths shape can be described as an “oblate spheroid”
It is flattened at the Poles, the surface is constantly changing due volcanic,
seismic and tidal activity
For practical navigation purposes we can describe the earth as a perfect sphere
The Earth rotates eastward on its Polar Axis
The 2 points where this axis meets the surface are the North and South
Geographical Poles (True North or True South)

2. Form of the Earth
Great Circles
A Great Circle is a circle drawn on the surface of the Earth with a plane that
passes through the centre of the Earth
Examples include:
• Meridians of Longitude
• The Equator
• Horizontal Paths of Radio Waves
A Great Circle divides a sphere into equal parts
A Great Circle is the shortest path between 2 points on the surface of a Sphere
such as the Earth

2. Form of the Earth
Small Circles
A Small Circle is a circle drawn on the surface of the Earth that is not a
Great Circle
The centre of a Small Circle is not at the centre of the Earth

Small circle of a sphere

2. Form of the Earth
Rhumb Lines
In navigation, a rhumb line is a line crossing all meridians of longitude
at the same angle
On a plane surface this would be the shortest distance between two
points.
Over the Earth's surface at low latitudes or over short distances it can
be used for plotting the course of a vehicle, aircraft or ship
For practical purposes a Great Circle direction and a Rhumb Line
direction may for distances under 200 nm be considered the same.

Image of a rhumb line, spiralling
towards the North Pole

2. Form of the Earth
Longitude
All Great Circles containing the Polar Axis are “Meridians of Longitude”
The prime meridian, based at the Royal Observatory, Greenwich in the UK,
was established by Sir George Airy in 1851
Meridians of Longitude are specified by their angular difference in degrees
East or West of the Prime Meridian
The Prime Meridian is either 0° if on the Atlantic side of the Earth or 180°
degrees if on the Pacific Ocean side of the Earth
If you divide 360° by 24 hours, you find that a point on Earth travels 15° of
longitude every hour

2. Form of the Earth
Latitude
Lines of constant latitude, or parallels, run east–west as circles parallel
to the equator
Latitude is an angle which ranges from 0° at the Equator to 90° (North
or South) at the poles

3. Position, direction and distance
Position Fixing
Latitude is used together with Longitude to specify the precise location of
features on the surface of the Earth
By convention a position is reported in the following format;
• Latitude in Degrees, Minutes, Seconds, N or S of Equator
Followed by
• Longitude in Degrees, Minutes, Seconds, W or E of the Prime Meridian

Seconds can be replaced by decimal parts of a minute eg 6 Seconds = 0.1

3. Position, direction and distance
Direction
Direction is the angular position of one point to another
We need a datum point to establish a reference point and for our purposes
we use a North-South Line through our current position (local meridian)
By convention we use a flat circle divided into 360 degrees to refer to
specific Headings (HDG) to our destination

3. Position, direction and distance
Describing Direction
The 4 Cardinal Points are;
North as 000, South as 180,
East as 090, West as 270
In between are all the other
points of the compass
A HDG of 300 is where on the
diagram?
A HDG of 115 is where on the
diagram?

3. Position, direction and distance
True North
Our initial reference point for calculating
the HDG to fly is True North or the
North Geographic Pole
This makes it easy to measure
angles and plot and measure
tracks on our Navigation Charts
However we normally do not
have an instrument in our aircraft
that can display our HDG relative
to True North

3. Position, direction and distance
Magnetic North
We have in our aircraft a compass that
can display our HDG relative to
Magnetic North
The Iron Core of the Earth acts as a
huge magnet with the 2 magnetic
poles being Magnetic North and
Magnetic South
Currently the Magnetic North Pole lies
in Hudson's Bay, Canada and it is
currently moving toward Russia at
between 55 and 60 km per year
The difference between True North
and Magnetic North is the Magnetic
Variation and varies depending on the
location of your aircraft
Movement of Earth's North Magnetic
Pole across the Canadian arctic, 1831–
2001

3. Position, direction and distance
Illustration of the Magnetic Field of the Earth

3. Position, direction and distance
Magnetic Variation
Navigation Charts display lines of equal Magnetic Variation, called Isogonals
We adjust our planned True HDG to a Magnetic HDG by allowing for the
Magnetic Variation to give us the Magnetic Track (TR) we need to follow to arrive
at our destination
Variation is labelled east or west
depending on whether the
Isogonal is east or west of the
Agonic Line (zero magnetic
variation)
If variation is East, magnetic
direction is less than true
If variation is West, magnetic
direction in more than true
(East is least, West is best)

3. Position, direction and distance
Magnetic Deviation
Magnetic deviation refers specifically to compass error caused by magnetized
iron within a ship or aircraft.
This iron has a mixture of permanent magnetization and an induced
(temporary) magnetization that is induced by the Earth's magnetic field.
To calculate the magnetic deviation for an aircraft compass is “swung” at
regular intervals using specific procedures.
The outcome is a calibration chart which is
displayed on or by the compass.
The deviation is generally minor , less than 2
degrees.

3. Position, direction and distance
Distance Measurement
For Navigation we use Nautical Miles to measure distances
1 Nautical Mile (nm) is the length, at the Earth's sea-level surface, of one
minute of arc of a great circle
The International Nautical Mile is 1,852 metres or 6,076.1 feet
Consequently, one degree of latitude (measured along a meridian) has an
equivalent surface distance of 60 nautical miles
For other Horizontal Distances we use Kilometres or Metres, for example
Runway length, visibility, horizontal distance from cloud
For Vertical Distances we use Feet, for example Altitudes to fly and vertical
separation from clouds

4. Calculate Air speed and Velocity
Speed
We fly in a mass of air that will move in accordance with the direction of
the wind and its velocity.
To accurately navigate we need to understand how the wind affects the
path and speed of our aircraft over the ground.
The 4 speeds we are interested in are:
• Indicated Airspeed (IAS)
• Calibrated Airspeed (CAS)
• True Airspeed (TAS)
• Groundspeed (GS)

4. Calculate Air speed and Velocity
Indicated Airspeed
Our Airspeed Indicator (ASI) in the C172 compares the total pressure
measured by the Pitot Tube of the air due to its movement relative to the
aircraft with the static pressure measured by the Static Vent.
Total Pressure – Static Pressure = IAS
The reading you obtain from the ASI is affected both by the speed and
the density of the air.
For manoeuvring the aircraft we use IAS as displayed by the ASI. For
example flap limiting airspeeds and approach airspeeds

4. Calculate Air speed and Velocity
Calibrated Airspeed
Our Airspeed Indicator (ASI) in the C172 is subject to 2 types of errors;
Instrument Error
This type of error is a result of friction within the instrument and/or bad
design.
Position Error
The location of the Pitot Tube and the Static Vents are critical to the
accuracy of the ASI. Incorrect positioning may lead to errors when the
airflow in the vicinity of the Pitot Tube and Static Vents is disturbed for
example by lowering flaps.
Calibration Table
The ASI is “calibrated” and the results are used to provide a Calibration
Table for pilot use to aid in interpreting the ASI. In practice the errors are
very small and we can generally assume IAS = CAS

4. Calculate Air speed and Velocity
True Airspeed
For navigation purposes we need to be able to calculate the effect of
changes in air temperature and air pressure on our speed through the air.
Once calculated this gives us our True Airspeed (TAS)
The ASI is calibrated in accordance with the international standard sea
level atmosphere. Changes in the air density (temperature and pressure)
will mean that the ASI does not display the TAS.
Temperature Changes
The warmer the air the less dense it is. Which means the aircraft must
travel faster through the air to maintain the same IAS, therefore TAS is
higher.
Pressure Changes
As we gain altitude there are less molecules of air and therefore the air is
less dense. Which means that as we gain altitude we will have a lower IAS
for the same TAS.

4. Calculate Air speed and Velocity
Calculating True Airspeed
The G1000 calculates and displays our TAS (below the IAS indicator).
We can however manually calculate the TAS with our Flight Computer.
We do that by reference to the Outside Air Temperature and the Pressure
Altitude.
TAS will always be higher than IAS.

4. Calculate Air speed and Velocity
Wind Velocity
A Velocity is a rate of change of position in a given direction and is therefore
a combination of both speed and direction.
The speed and direction of an air mass is a velocity.
By convention wind speed and direction is provided in the following format;
• Direction (3 digits)/ Speed (2 or 3 digits)
Example
A wind of 20 knots travelling from the north would be expressed as 360/20

4. Calculate Air speed and Velocity
Weather Reports
Weather reports will provide wind information in the following format

Degrees Magnetic
For surface winds eg for take off or landing in an ATIS or TAF
Degrees True
For navigating through an air mass in an ARFOR
This means that we must adjust the winds we use in navigating from one
place to another to take into account the Magnetic Variation.
See the Bureau of Meteorology – Aviation section for detailed
information on aviation weather reporting.
www.bom.gov.au

4. Calculate Air speed and Velocity
Groundspeed
The GS is one of the most important pieces of information a navigator
needs to accurately fly to your destination.
GS is found by adjusting your TAS for the effect of wind (direction and
velocity).
Example
TAS = 120 knots, HDG = 360, Wind = 360/25
Calculation – 120 knots – 25 knots of wind = GS of 95 knots
(As there is nil cross wind the calculation is simple. We will try more
complex examples using the Flight Computer to calculate our GS in future
lessons)

4. Calculate Air speed and Velocity
Time Intervals
We use the GS to calculate a TI which in turn dictates your fuel
requirements, the time you will arrive and the payload you can carry.
We can check our GS as the flight progress by comparing the time it takes
to fly over 2 known points with the distance actually travelled.
Example
Distance travelled between Alpha and Bravo = 90nm
Time Interval to travel between Alpha and Bravo = 45 minutes
GS = 90/45 or 2nm per minute therefore GS = 120 knots

4. Calculate Air speed and Velocity
Triangle of Velocities
The Triangle of Velocities is typically used to calculate HDG and GS
In order to use the triangle we must know at least two of the following:
• Track (TR) and Groundspeed (GS)
• Wind (Direction and Strength)
• Heading (HDG) and True Airspeed (TAS)
Wind

Heading and True Airspeed

Track and Groundspeed

5. Altimetry
Vertical Navigation
Unlike driving a car when flying we operate in a 3 dimensional environment
and we need to have some way to navigate both horizontally and vertically
Terrain Separation: We need to ensure we know where we are in relation to
the ground to ensure a safe flight to our destination
Traffic Separation: We need to have a common system of determining our
altitude to ensure separation from other aircraft
Aircraft Performance: How high or low we fly will affect aircraft performance
and how efficiently we can get to our destination

5. Altimetry
Vertical Measurement
Altitude: Measured by reference to Mean Sea Level (MSL)
For example at Parafield we fly our circuit altitude is 1,000 feet Above Mean Sea
Level (AMSL) so all aircraft are at the same Altitude
Height: Measured by reference to a point above the ground
For example if we were flying above Mount Lofty at an altitude of 3,500 feet we
would be at a height of 727 feet above Mount Lofty
Flight Level: Measured by reference to a common pressure datum of 1013.2 hPa
For example above 10,000 aircraft set 1013 hPa on their Altimeters and fly at
“flight levels” such as FL 150 (15,000 feet)

Altitude
Sea

Height
Ground

5. Altimetry
Altimeter Settings
QNH: Setting the Altimeter to a specified QNH will indicate aircraft
Altitude (AMSL)
QFE: Setting QFE (Field Elevation) will determine the altitude above the
ground
Note: QFE is normally only used in some recreational aviation activities
such as aerobatics or parachuting
ISA Pressure: The International accepted standard pressure at sea level is
“1013.2 hPa”
This is used to establish “flight levels” for aircraft flying at high altitude, for
example in Australia above 10,000 feet, in the USA above 18,000 feet

5. Altimetry
QNH Settings
We set the actual pressure or “QNH” before take off as the actual pressure
is seldom the same as the ISA standard of 1013.2.
Setting the QNH on the Altimeter sub scale will provide the pilot with the
actual altitude of the airfield and in flight the altitude of the aircraft AMSL.
Pressure Changes
During the day the actual pressure will change and according the actual
QNH will change.

Pressure changes are advised in aviation weather forecasts, by ATC and by
an airfield ATIS.
If we are on the ground we can determine the QNH by setting the known
airfield height above mean sea level and reading the QNH off the altimeter
sub scale.

5. Altimetry
Selection of Altitudes
VFR Hemispherical
Altitudes Below 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Altitudes
(Area QNH)

1,500
3,500
5,500
7,500
9,500

2,500
4,500
6,500
8,500

Hemispherical Cruising Altitudes are optional below 5,000 feet
however it is recommend that wherever possible hemispherical
altitudes should be flown

Why is it important to fly at the correct altitude?
IFR aircraft fly at Evens or Odds Altitudes

5. Altimetry
Selection of Cruising Levels
VFR Hemispherical Cruising Levels Above 10,000 Feet
Magnetic Tracks

000 - 179

180 - 359

Cruising Levels
(1013 hPa)

115
135
155
175
195

125
145
165
185

FL 115 is not available when the Area QNH is less than 997 hPa
FL 125 is not available when the Area QNH is less than 963 hPa

Oxygen is required for flight above 10,000 feet.
VFR flight is prohibited above 20,000 feet.

Questions?