Post-September 11 air travel security concerns have spurred Boeing to develop and test a tamper-proof, remote-controlled autopilot system. ... The idea goes like this: If anyone attempts to force their way into the cockpit, autopilot can be activated manually or by pressure sensors that are installed in the cockpit door....Once the "uninterruptible autopilot system" is activated, it cannot be reversed. Ground controllers can then guide the plane to its destination via remote digital control...
http://www.engadget.com/2007/03/08/remote-controlled-autopilot-to-prevent-hijacking/
I call B.S. Airline pilots will NEVER allow it.