This is strictly anecdotal evidence, but I'll throw in my 2 cents here. I have a private pilot certificate and am working toward an instrument rating right now, which involves being in continuous contact with air traffic control, flying in low / zero visibility conditions, and relying on aircraft instruments to guide me on landings. On numerous(if not all), I've had my iPhone with me, switched on and even in my lap a…
Unlike a Cessna, a 767 has a fly-by-wire system supported by a data bus (e.g. ARINC-429) running the length of the aircraft, often close to the passenger cabin. Presumably, GSM/CDMA signals could interfere with this.