Transponder's fate may prove key to solving Malaysia Airlines puzzle - CNN.com
The electrical system aboard the plane is so robust and the transponder draws so little power that it would be one of the last pieces of equipment to go dark, even after a catastrophic event like an engine explosion or a breach of the cabin and rapid decompression, he said.
"I'm in a head-scratching mode," Nance said. "The most likely probability is that a human hand turned that off. Then you get into the logic tree of who and why and there aren't that many channels in that tree." He added, "This is beginning to look very, very much like a hijacking."
A former Federal Aviation Administration safety inspector agreed. David Soucie, author of "Why Planes Crash," cited the redundant electrical, charging, battery and communications systems on Boeing 777s. Much had to go wrong for the aircraft to lose its transponder and then to veer off course, he said, adding that it stands to reason "that someone forced those pilots to take control of the aircraft and take it off course."
Turning off a transponder requires a deliberative process, said Peter Goelz, former managing director of the National Transportation Safety Board. "If someone did that in the cockpit, they were doing it to disguise the route of the plane," he told CNN. "There might still be mechanical explanations on what was going on, but those mechanical explanations are narrowing quickly."