Transcript Land Navigation - University of Arizona

Land Navigation
SSgt. Scarfe
“You cant kill the enemy if you
can’t find him”
Terminal Learning Objective

Without the aid of reference, complete a
day and night land navigation orienteering
course
Enabling Learning Objectives
Know how to:
 Inspect a compass
 Find your pace count
 Shoot an azimuth
 Set compass for night Navigation
 Dead Recon
 Terrain associate
OCS Land Navigation

Focus on skills needed to complete the
OCS land navigation course.
Step 1: Inspect your compass
Visual inspection: Open your compass
to ensure glass is not cracked or clouded,
ensure compass dial does not stick.
 Inspect front cover to determine if
sighting wire is bent or missing.
 Place eye piece flat against the glass to
ensure slot lines up with sighting wire.

Inspect your compass cont.

Check bezel ring, it should make distinct
“clicks”
Inspection for Night Clarity
The following parts should appear
luminous:
1) Two dots at opposite ends of the sighting
wire.
2) Luminous line on the crystal.
3) Luminous line on the north seeking
arrow.
4) Luminous dots under “E” and “W”
Limitations of the Compass
Metal objects and electrical sources
can affect the performance of a
compass:
1) High tension power lines 55m
2) Field gun, truck or tank 10m
3) Telephone wires or bobbed wire 10m
4) Machine gun 2m
5) Rifle .5m
Step 2: Calibration
A compass in good working order is very
accurate, but it should be checked
periodically on a known line of direction.
 To complete this step you must
understand how to shoot an azimuth.

What is an Azimuth?
An azimuth is
defined as a
horizontal angle
measured from a
base line.
 In other words, the
direction you want to
go.

Base Directions

There are three universal base directions
in common usage: True North, Magnetic
North, and Grid North.
True North

True north is at the North Pole. Lines of
longitude on a globe indicate this baseline
direction. True north is seldom used by
platoon commanders. It is usually used in
celestial navigation.
Magnetic North
Magnetic north is the direction in which
the compass points. There are no
magnetic lines shown on the map. The
magnetic north pole is located just north
of the Hudson Bay in Canada.
 Method used when walking the terrain.

Grid North
Grid north lines are a device of
mapmakers and enable us to plot direction
of the map. They are indicated by the
vertical, parallel lines of the map. When
the mapmaker interprets the rounded
earth surface on a flat map sheet, it is
necessary to create this artificial base
direction.
 Method used when plotting on your map.

Magnetic North

When using a compass magnetic north is
your base line.
Declination Diagram
Step 3: Shooting an Azimuth

Two methods:
1) Compass to cheek
2) Center hold
Compass to Cheek Procedures
1)
2)
3)
4)
Fold back cover until it is just less than
90 degrees from the base.
Fold rear sight slightly forward of 90
degrees.
Look through rear sight slot and align
the sighting wire with the desired object.
Glance at the dial to read azimuth,
ensure that the dial is floating.
Choosing a Steering Mark
Choose an object that
stands out.
 Look at the terrain
that you will be
crossing.
 If you loose sight of
your steering mark,
shoot again.

Center Hold Technique
1)
2)
3)
4)
5)
6)
Open compass so that it is fully extended.
Move lens to the 90 degree position.
Place thumb in the thumb loop.
Rest compass on the base of your extended
thumb, align index fingers with the long edge
of the compass.
Pull your elbows in tight.
Rotate body until desired azimuth is reached
Compass to Cheek vs. Center Hold
– Compass to cheek is can be more accurate
but also more time consuming. Good for open
terrain during the day.
– Center hold will be used during conditions of
limited visibility, or thick brush.
– You can use a combination of the two
methods.
Step 4: Determine your Pace Count
Another of the basic tools required for
successful land navigation.
 Although it is not an exact science,
knowledge of your pace count can provide
you with a major portion of the
information required to determine your
location on the ground at any given time.

Average Pace count
To determine your pace count you must
walk a straight line distance that
represents the terrain that you will be
navigating.
 For simplicity 100m is the norm for finding
your pace count.
 Step off with the right foot, and count
every time your left foot strikes the deck.

Pace Count Between Points
Determine distance to be traveled, we
will use 370m
2) Set up problem: 370m x 60p
100m
3) Cancel like units.
4) X = 222p
1)
Say it took 250 Paces, instead of
222 paces
Use “Algebra” to correct your pace count
on the fly.
 Ex: 250 = 370m x (X)
100m
-New pace count = 68p for every 100m

Factors Affecting Pace
Slope: Lengthens downhill, shortens
uphill.
 Winds: Tailwinds lengthen, headwinds
shorten
 Surface: Loose surfaces tend to shorten
pace.
 Elements: Same as above.

Factors Affecting Pace
Clothing: Heavier burdens shorten pace.
 Stamina: Fatigue will shorten pace.
 Visibility: Usually shorter at night.
 Wearing one boot: If missing left boot,
you will tend to drift left and vice versa.

Dead Reckoning
Method you will be graded on during OCS.
 This process is simply and blindly following
an established azimuth for a specific
distance without regard to terrain.

Procedure
1) Locate your starting point and objective
on the map or card.
 2) Determine the grid azimuth between
the two points and convert it to a
magnetic azimuth
 3) Determine the distance to your
objective and convert it to a pace count.

Procedure Cont.
4) Set the magnetic azimuth on your
compass: 1 Rotate the compass until the
desired azimuth falls under the fixed black
index line.
 5) Holding the compass in hand, turn the
bezel ring until the luminous line is
matched up with the north seeking arrow.

Procedure Cont.
5) To follow the azimuth, use the centerhold technique and turn your body until
the north-seeking arrow is aligned with
the luminous line.
 6) Proceed in the direction of the front
cover, along the azimuth, the required
number of paces.

Factors That Cause Drift
1) Physical attributes. Example: One leg
may be shorter than the other, causing a
tendency to deviate.
2) Unbalanced load. An unbalanced load
may pull you slightly off-balance, causing
deviation from your intended direction of
movement.
Factors That Cause Drift
3) Elements. There is a normal tendency to edge
away from rain, snow, or the sun in order to
receive the impact over your shoulder or on your
back.
4) Movement around obstacles. Right-handed
people have an inherent tendency to move to
the right around an obstacle, while left-handed
people move to the left. A wise navigator
alternates his direction of movement around
obstacles.
Terrain Association

Terrain association. This is the process of
using terrain features to guide the
navigator to the objective with little or no
reliance on the compass. Terrain
association is, by far, the technique of
choice, as it allows the navigator to know
his location at all times just by referencing
the surrounding terrain. (map required)
Procedure
1) Determine your start point and objective.
2) Identify the terrain features between
these points.
3) Proceed to your objective, "reading" the
terrain along the direction of your
movement.
Bypassing Obstacles

Utilizing the 90° Offset rule to bypass
obstacles. This technique is used when
you are not able to cross a sizable
obstacle. To execute this technique, you
simply create a "box" around the obstacle
by adding and subtracting 90° to your
azimuth. You must keep track of your pace
count during the evolution.
Set compass for night Navigation
1) Rotate the bezel ring until the luminous
line is over the fixed black line.
2) Find the desired azimuth and divide it by
three. The result is the number of clicks to
rotate the bezel ring.
3) If the desired azimuth is smaller than a
180 degrees, the number of clicks on the
bezel ring should be counted in a
counterclockwise direction.
Setting compass for Night
4) If the desired azimuth is larger than 180
degrees, subtract the number of degrees from
360 and divide by 3 to obtain the number of
clicks.
5) Count the clicks in a clockwise direction.
6) With the compass preset as described, assume
a center hold technique and rotate your body
until the north seeking arrow is aligned with the
luminous line on the bezel.
Night Land Nav
7) Proceed forward in the direction you are
facing or follow the direction the luminous
dots which are aligned with the fixed black
index line containing the azimuth.
8) Do not just follow the north seeking
arrow.
Example Problem
If the desired azimuth is 51 degrees:
divide by 3, which equals 17 clicks
counterclockwise
 The desired azimuth is 330 degrees:
360 - 330 = 30
30/3 = 10 clicks clockwise.

Trouble Shooting
Measure 1, 2, 3 times, cut once.
 Don’t panic, and begin to wander.
 Know which way you tend to drift, this will
help when you reach the end of your pace
count.
 If all else fails, haul ass back to your start
point and start again. (some points are
very close together)
 Continually check your azimuth.

Questions