The primary reason is they don't want people distracted during take-off and
landing... otherwise they wouldn't make you turn off your iPod (no radio),
but they don't ask you to take off your headphones if you're plugged into the
in-flight entertainment system (the intercom overrides the audio).
If interference issues were the primary concern, then they would inspect
devices to make sure they were turned off or they would have some sort of
method for RF detection. I've left my phone on in my bag plenty of times
and I'm sure I'm not the only one.
Oddly, the instructions for in-flight wifi on Delta include instructions
on how to connect with an iPhone... a device that does not let you turn off
the cell radio independent of the wifi radio.
Besides episode 49 of Mythbusters covered the "Cell phones disrupt airplane
navigation" myth![]()
Well, you can believe what you want, but I'll stick with the actual references:
FAR 91.21 said:a) Except as provided in paragraph (b) of this section, no person may operate, nor may any operator or pilot in command of an aircraft allow the operation of, any portable electronic device on any of the following U.S.-registered civil aircraft:
(1) Aircraft operated by a holder of an air carrier operating certificate or an operating certificate; or
(2) Any other aircraft while it is operated under IFR.
(b) Paragraph (a) of this section does not apply to--
(1) Portable voice recorders;
(2) Hearing aids;
(3) Heart pacemakers;
(4) Electric shavers; or
(5) Any other portable electronic device that the operator of the aircraft has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.
(c) In the case of an aircraft operated by a holder of an air carrier operating certificate or an operating certificate, the determination required by paragraph (b)(5) of this section shall be made by that operator of the aircraft on which the particular device is to be used. In the case of other
aircraft, the determination may be made by the pilot in command or other operator of the aircraft.