I notice that American Airlines bans the use of GPS receivers on board. Does anyone know why? I've searched through the archive and although there has been discussion on this subject in the past, nobody has suggested why American Airlines should ban a harmless device that is passive and does not transmit.

Also on a related matter, is American Airlines one of those airlines that bans the use of mobile phones when the aircraft doors are open? Such a policy would not adhere to the guidelines issued by the European Joint Aviation Authorities at http://www.caa.co.uk/docs/33/FOD200119.pdf

Does anyone know what the FAA's guidelines are on both these matters?