I had a Garmin eTrex in about 2009 that worked fine on planes:



I think the problem with using cell phone GPS on planes is that the GPS chips in cell phones are Assisted-GPS, which means they need location data from the cellular network to get a position/speed fix. I evilly took my phone out of airplane mode on approach once, managed to get a signal, and my GPS speed app showed we were going about 250 mph.