Originally Posted by
KRSW
There's another option: Flightaware.com. Let the plane's ultra-expensive GPS+transponder do the heavy lifting.
[MENTION=692075]TGarza[/MENTION]: I can confirm that iPhones and iPads with cell modems DO NOT need internet or even an active SIM card for the GPS to work.
I can confirm this. I routinely use GPS apps while hiking in areas with no cell service. I have also once tried a phone with no SIM installed and using a radio relay--the GPS part of it worked, under the conditions the radio range turned out to be too short to be of much use for what I was after. (It provided a text version of a walkie talkie, but used your phone as the interface.)