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Propellor Head
27th May 2009, 13:13
The GAO have released a report that a combination of ageing satelllites and delays in the replacement program, the GPS performance may become degraded.

The question is: how will this affect the useability of GPS approaches?

kijangnim
27th May 2009, 13:42
Greetings,
this is the website from which details should be coming from:
Subscribe/Unsubscribe: http://cgls.uscg.mil/mailman/listinfo/nanu (http://cgls.uscg.mil/mailman/listinfo/nanu)
If you subscribe you will recieve all sorts of notifications, including sat launches....
It is true that in space they dont last long, however, so far 32 are orbiting, and we are using 24 (excluding GLONASS).
Having said that, 5 satellites (with baro aiding) in view and a good geometry is what is needed to to shoot an RNP, NPA, RNP RNAV approach, with GPS as the primary sensor:ok:.

kijangnim
27th May 2009, 14:20
Greetings,
there is a website, with public access, where you can subscribe, and recieve GPS information called NANUs, the website is managed by the US coast guard.
They are still launching satellites, big time, because, LEOs dont have a very long life time, especially when they use a lot of energy, to be kept on the ephemeris, and to transmit/receive GPS data.
Nevertheless you just need 5 satellites (baro aided capability, with RAIM handling Sat geometry as well) to do an RNAV RNP, RNP, NPA, GPS approach, with GPS as a primary sensor.:ok:

VinRouge
26th Jun 2009, 15:31
If you are ever worried, you can notam ICAO KGPS to find out how reliable the system is. I only discovered this the other day. :ok: