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GPS NAVIGATION




Global Positioning System (GPS) is a space-based radio-navigation system. The GPS system is accompanied by the RNAV guidance which makes it a worldwide navigation system.

The GPS satellites are operated by the Department of Defense (DOD).

To get status information for the satellites:

  • U.S Coast Guard navigation information service, 703-313-5907 or www.navcen.uscg.gov.

  • Also, satellite status will be available via a NOTAM.

There are no symbols to identify a GPS on any aeronautical charts since the GPS satellites are a space based systems. These system is unaffected by weather and provides a worldwide common grid based on latitude and longitude.


The GPS constellation has 24 satellites orbiting the earth on six different planes. It is setup so there are a minimum of five satellites always observable by a user anywhere worldwide.

The GPS receivers need at least four satellites to create a three-dimensional position. (latitude, longitude, and altitude) and the fourth satellite is used for time solution. These receivers compute navigational values, such as distance and bearing to a waypoint, groundspeed, etc., by using the airplanes known position.




RAIM

Receiver Autonomous Integrated Monitoring (RAIM) is used to determine if any satellites are providing any corrupted information. It uses six satellites in view to isolate the corrupted signal and remove it from that navigation solution.



GPS NOTAMS

GPS Satellite outages are issued as a GPS NOTAM, both domestic and internationally.


The only way for a pilot to determine if there are any GPS outages, the pilot needs to have RAIM availability program.

  • To get GPS RAIM availability information, must request GPS aeronautical information from the FSS.

  • GPS RAIM can be obtained 1hr before and 1hr after your ETA, or during a 24hr period at a particular airport.


Tip:

Student Pilots should not use GPS during flight training, recommended that Private Pilots and more experienced pilots use it.


Remember:

  • Operated by the Department of Defense (DOD).

  • The GPS constellation has 24 satellites orbiting the earth on six different planes.

  • GPS receivers need at least four satellites to create a three-dimensional position. (latitude, longitude, and altitude) and the fourth satellite is used for time solution.




References:


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