This question would probably best be answered by a pilot or airplane electronics tech. I've always wanted to listen to the pilots on board planes I was on but I knew that it was against aircraft rules. I've often had the scanner turned on while the plane was on the ground but never had the guts to leave it on in the air -- just in case. Just in case it actually does cause some kind of interference. If I actually turn it on while it's airborne, or if I just leave it tuned to one frequency (not scanning), what are the chances of me actually causing a problem? Don't people secretly use cellphones on planes all the time in the bathrooms and stuff? And what about the airphones? Outside of FAA restrictions and such, what is the truth about this?