The pilot of Malaysia Airlines flight MH370 may have been clinically depressed, leading him to starve the passengers of oxygen and then crash into the sea in a murder-suicide, according to a new account.

MH370 was on its way from Kuala Lumpur to Beijing on March 8, 2014, with 239 people on board, when it vanished and became one of the world's greatest aviation mysteries.

Friends of the the pilot, Zaharie Ahmad Shah, 53, told aviation specialist William Langewiesche that he had become obsessed with two young models he had seen on the internet after his wife left him, and that he "spent a lot of time pacing empty rooms."

A fellow pilot said: "Zaharie’s marriage was bad. In the past he slept with some of the flight attendants. And so what? We all do. You’re flying all over the world with these beautiful girls in the back. But his wife knew."

There is a strong suspicion among investigators in the aviation and intelligence communities that he was clinically depressed.