pilots had to change course because they were looking for an emergency airport. they were at some point overtaken by whatever it was, smoke, fire, or some kind of problem. and the plane was then left to fly itself after it had been programmed to go on that course. that's what we call a zombie option. >> reporter: it happened with flight 522 which flew on autopilot for nearly two hours before crashing in athens in 2005. pilots forgot to switch the pressure rye zags switch from manual to auto. all on board passed out and froze in their seats. so far, we know the malaysian flight was flying for at least seven hours based on pings emitted from the plane. whatever took out the plane's transponder and acars was mechanical and could have damaged the electronic nerve