Don't know what your definition of a brain is here, but the plane you are sitting in has a fully functional GPS system, so why would it not work? Sure if you go beyond the height of the satellites you are going to have to do some fancy calculations, but in a commercial airliner you are fairly safe. Whether you can pick up much inside the passenger compartment of a plane I don't know (although I don't see why not). The only other thing I could foresee, is that to enable a quick pickup, most sold GPSs make certain assumptions to get a lock, and one of those assumptions may be that you are not going several hundred miles an hour, several miles up, so it is down to the individual unit as to how it performs.