I left my Garmin Nuvi on by accident in my jacket pocket placed in the overhead bin on a recent trip from SFO-LHR. On returning home, there was a nice display of our track outbound and up over the Great Lakes. The trace stopped around YYZ, where I guess the battery power gave up.
I also got a new record high speed on my database ... 697mph
For non accidental use, I'd ask the cabin crew of course
