Originally Posted by
Weez_1000
IIRC the gps feature on the iPhone is AGPS=Assisted GPS which triangulates your signal off cell towers. Very very unlikely it will ever work unless low to the ground and over some pretty strong cell towers.
As per my above comment - this is why it can get a real GPS fix quickly when on the ground - the mobile towers provide an approximate location, and the GPS uses that data to "look" for the satellite signal more quickly. Without a mobile signal it will take longer, but it will work. As an example - you can use the GPS on the iPhone when the mobile radio is switched off.