Transcript Global Positioning System

Global Positioning System
What Flight Instructors need to teach!
What your pilot/student needs to
know!
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James D. Jacobsen
Washington Flight Standards
District Office-27
Dulles International Airport
• I’m
• Always
• Here to Help!
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GPS Generally
• The GPS is a U.S. satellite based radio
navigational , positioning, and time transfer
system operated by the DoD.
• The system provides highly accurate
position and velocity information and
precise time on a continuous global basis to
properly equipped users.
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There are two levels of service
• Standard Positioning
Service (SPS)
• Precise Positioning
Service (PPS)
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(SPS) and (PPS)
• 100 meters-95%
• 300 meters-99.99%
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• PPS Is more accurate
than SPS; however it
is limited to authorized
U.S. and users who
can satisfy specific
U.S. requirements
Each satellite transmits specific
code
• It is called a “CA” or
Course/Acquisition
code.
• It contains information
on the satellites
position,GPS system
time, clock error and
the health and
accuracy of the data.
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Your Receiver...
• matches each satellites CA Code with an
identical copy of the code contained in the
receivers database.
• By shifting the receivers code its matching
the satellite and by comparing this shift with
the satellite internal clock...wala!..magic!
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Measuring distance
• The distance derived from this computing is
called pseudo-range because it is not a
direct measurement but rather, measurement
based on time.
• Your receiver needs to know the satellites
exact position in space
• The receiver does the math to tell you
where you are!
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There are 24 satellites
• A minimum of five satellites are always
observable by a user anywhere on earth.
• On December 8, 1993 the FAA granted
approval to use GPS to conduct oceanic,
domestic enroute, terminal IFR operations,
and certain instrument approach procedures,
under specified conditions:
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General Requirements
• The GPS equipment must be approved in
accordance with TSO C-129.
• Aircraft using GPS under IFR must be
equipped with an alternate means of
navigation.
• Procedures must be established if satellite
reception is impaired, i.e.. delay or cancel
flight.
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...more conditions
• The GPS flight must must be conducted in
accordance with FAA-approved flight
manual or flight manual supplement.
• Aircraft navigating by GPS are considered
(by ATC) to be RNAV aircraft. The “/R” on
the flight plan tells them that.(GPS goes in
remarks)
• Prior to flight GPS NOTAMS
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There are/were three Phases of
operations...
• Phase 1 You can use GPS only if groundbased nav equipment is monitored and
operational.
• Phase II GPS without actively monitoring
ground-based nav equipment..avionics must
be installed an working..but not turned on.
• Phase III is where approach plates are titled
“GPS” and you do not need other nav’ gear.
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References
• Aeronautical Information Manual
(Navigation Aids Chapter 1 Page 1-36)
• FAA Advisory Circular AC 90-94
“Guidelines for using GPS for IFR...”
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Let’s talk about the 3 Phases!
• Phase 1 ended February 1994 when the
FAA declared GPS operational for civil
operations.
• Phase II began February 1994 when the
FAA declared the system useable.
• (Don’t need to actively monitor groundbased as long as something tells you GPS is
working.
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Phase III
• Phase III requires modification of the
instrument approach procedure name to
include “GPS” on the chart. You need
neither the traditional avionics nor the
ground station navaid(s) to be operational or
monitored to fly non precision approach...if
RAIM is monitoring the integrity of your
GPS System.
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What is “RAIM”
• Receiver Autonomous Integrity Monitoring.
• Your receiver tells you if you are receiving
adequate signal to fly the GPS...if not, delay
the flight or cancel as appropriate.
• The reason being that Phase I,II,& III have
additional criteria:
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To repeat...
• GPS must be TSO’d
• Receiver should have database with airport
of choice...and no LOC, LDA or SDF
approach.
• If approach not in database..it is probably
unsafe that is why it is not there.
• GPS should store all waypoints depicted on
the approach chart.
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...more
• Approach must be flown in accordance with
FAA Aircraft Flight Manual or flight
manual supplement.
• Any required alternate airport should have
an approved instrument approach other than
GPS...NOTAMS is a pilot responsibility.
• The GPS overlay approaches are limited to
the U.S. national airspace.
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and last but not least...!
• Procedures should be established by the
pilot in the event of GPS outages..meaning
rely on other equipment, delay departure or
discontinue IFR operations.
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Pilot Operations
• To quote AC 90-94, “...All pilots must be
thoroughly familiar with GPS equipment
installed in the aircraft and its limitations.”
• The pilot should follow the specific start-up
and self-test procedures for the GPS
receiver as outlined in the FAA AFM or
Flight Manual Supplement.
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GPS NOTAMS
• Request from Briefer
• Use identifier “GPS”, through the Direct
User Access Terminal System (DUATS)
• ..remember, if the NOTAMS indicate GPS
is not working...the approach is not
authorized.
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Appropriate Approach
• The pilot must select
appropriate approach
from GPS receiver to
determine RAIM
integrity for that
approach.
• If GPS is out amend
“/R” flight plan.
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How about the alternate?
• If the GPS ain’t working...the alternate must
have an approved approach...other than
GPS or..Loran-C!”...which is anticipated to
be operational at the estimated time of
arrival!”
• What do you use?
• ILS, NDB...?
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GPS
Now that we’ve given you something
to think about...
Let’s talk “Black Box.”
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That’s all Folks!
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