There are theoretical limitations on the operation of GPS receivers above a certain altitude or velocity. This was introduced by the US government to stop (undesirable) people using them on missiles. As far as I recall the altitude limitation is 60000 feet, and velocity is limited to 999mph (some receivers cease to operate when both limitations are reached, others when only one is reached!). Since there are plenty of weapons systems that operate below this, it seems a bit of a minor limitation, and of course jamming or deliberate cessation of the C/A signal would stop that from working anyway. Of course, GPS receivers could be built outside of the USA, and some are built for purposes which would need to operate outside of that range, spacecraft being an important one.
A plane in some respects isn't a bad place to put a GPS receiver, because it has a nice unrestricted view from horizon to horizon, but the metal shell of most aircraft does operate as a fairly effective Faraday cage. Since GPS receivers are on the edge of working from an RF budget POV, it doesn't take a lot to stop them. It's unlikely much electronic equipment in an aircraft would interfere with a GPS receiver, because anything which radiates that badly, is likely to interfere with some of the aircraft's own systems. Good EMC/EMI performance within an aircraft, which is a damned good idea if you're an avionics manufacturer, will require that, and the only thing which will radiate significantly are transmitters, which will not be transmitting on the GPS frequencies, because it would interfere with GPS receiving equipment, which the aircraft uses itself, so would not be allowed by the CAA or FAA.
