you're barking up the wrong tree:

Boeing's scary new autopilot patent
...once activated, removes all control from pilots to automatically return a commercial airliner to a predetermined landing location.

...the system has its own power supply, independent of the aircraft’s circuit breakers. The aircraft remains in automatic mode until after landing, when mechanics or government security operatives are called in to disengage the system...


http://www.flightglobal.com/Articles...+hijacked.html

Cheers
George