This has probably been asked before, but I couldn't find it in the FAQ, so what I want to know is, can one use one's GPS on a commercial airplane to see when you are crossing the equator for example? Is it allowed by the airline authorities? If one is allowed to use it, does the signal from the satellites penetrate the fusilage? I have noticed with some motor cars that the bodywork interferes with reception. In other cars it isn't a problem.