Experts agree with Prime Minister Najib that evidence indicates the plane was deliberately diverted. Mikael Robertsson of global aviation tracking service Flightradar24 says the way the plane’s communications had been shut down indicates that someone on board with aviation expertise was involved. Robertsson says the shutdown was timed to make it likely that the loss of communications would not be realized for some time. Robertsson says:
Always when you fly, you are in contact with air traffic control in some country. Instead of contacting the Vietnam air traffic control, the transponder signal was turned off, so I think the timing of turning off the signal just after you have left Malaysian air traffic control indicates someone did this on purpose, and he found the perfect moment when he wasn’t in control by Malaysia or Vietnam. He was like in no-man’s country.
It is likely that one or more members of the crew was involved, he says, but emphasizes that crew involvement has not yet been proven. Chinese aviation expert Xu Ke agrees that at least one crew member, most likely one of the pilots, seized control of the plane, either willingly or forcibly:
The timing of turning off the transponder suggests that this involved someone with knowledge of how to avoid air traffic control without attracting attention. You needed to know this plane, and you also needed to know this route. … [T]he likelihood that a pilot was involved appears very likely. The Boeing 777 is a relatively new and big plane, so it wouldn’t be anyone who could do this, not even someone who has flown smaller passenger planes, even smaller Boeings.