Re: Rosie O'Donnell breaking the lie about 911on the view
no it's not a 4-digit code to turn off the transponder.
it's a 4-digit code to enter that you've been hijacked, and those keypads are located all over the plane.
the transponder is trickier, the pilot/terrorist would actually have to remove the control panel (!) to get at the transponder unless they magically knew how to pull the circuit.
here's the faa's requirements pre 9-11 and why they claimed they should be changed (seemed easy enough to me, punch in 7500 and you're done).
Current Requirements
All air carrier aircraft are required to be equipped with an ATC
transponder (see 14 CFR 91.215 and 121.345), which in normal operation
provides a radar beacon identity code and altitude (Modes 3A/C) for ATC
use in controlling aircraft in en route and terminal areas of
operations. During normal operations it is expected that a flight crew
could manually dial-in a new ATC-directed Mode 3A transponder radar
beacon code, through the transponder control panel, in roughly five to
ten seconds. However, under the stress of a hijack situation it may
take considerably longer than ten seconds to dial-in the designated
hijack alert code, or it may not be possible at all if the flight crew
is distracted by a flight deck intruder.
The designated hijack alert code is ``7500,'' which is defined in
section 2.1.4 of Volume IV of the International Civil Aviation
Organization (ICAO) Annex 10 as the appropriate code to indicate to ATC
that an aircraft is being subjected to unlawful interference.