investigators have. the plane had lost cabin pressure and all on board were dead. jet fighters shallowing the plane could do nothing to save it as it eventually ran out of fuel. could flight 370 have become a so-called zombie plane. >> at some point overtaken with smoke, fire, some kind of problem. the plane then left to fly itself. that's what we call the zombie option. >> happened with flight 522 which flew on autopilot before crashing outside athens in 2005. pilots forgot to turn the pressurization switch from manual to auto at 34,000 feet. all 121 on board cast out and froze in their seats. so par we know the malaysian flight flew seven hours based on