Used a Garmin car sat nav on a flight from Nice to the UK a few years ago while in a window seat without any difficulty. I just held it up to the window after the take off phase, it initialised and away it went. Great fun watching the display and hearing the ping every time we passed overhead a 30mph speed limit zone.
As an inadvertent added bonus, I moved up several notches on the Esteem-O-Meter with my teenage daughter's male friends when I could show them that the maximum speed displayed on the sat nav was 564mph. You could see them wondering how their Corsas and Leons were ever going to reach that sort of speed .....
