[quote=tom pettit]So how come I can't just use the gps alone? It seems like it is much more
flexible, and then I wouldn't be as dependent on what ground based stuff was
available.
tom

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you can do that - but forget about saving money. you would need the garmin 480 GPS which can be used as a sole-means-of-navigation device. be ready to fork out at least $15,000 by the time it's installed with all the required hardware and config though.

as per others on this thread, i question the wisdom of relying only on a GPS - for example, last time as i passed through richmond (KRIC) a notam said GPS signal may or may not be adequate for navigation. and just like the NOTAM said, we got a RAIM alert just before passing the FAF.

another time in albukerque, we were on final descent, navigating by GPS at night when the unit went dead (welll, not dead, but it gave a message of "no signal" or something similar). turns out there were some military exercises going on in the area that included jamming the GPS signal. that final leg made for some interesting scrambling in the cockpit looking for maps, beacons and frequencies to navigate "a la VHF" before we sailed past where we were going...

:-)

francois