It's a mystery that continues to baffle experts and conspiracy theorists alike. What happened to the Malaysian Airlines flight MH370?
It's been five years since the flight disappeared, and now a former pilot has put forward a particularly 'out there' theory about the man who flew the missing plane.
Luke Warfield used to fly Boeing planes, and he has told the Daily Star that he thinks the pilot of the flight, Captain Zaharie Ahmad Shah, could be the main suspect in a potential hi-jacking plot.
He bases this hot take on the fact that the pilot's cabin contains the only offensive weapon that would have been on board the craft - a fire axe.
Basically, they keep an axe directly beneath the flight deck in case of serious emergencies. After all, in the event of a fire, the pilot might have to hack through a door. Mr Warfield has offered the theory that the captain could have used this axe on his co-pilot, Fariq Hamid.
That would have meant that during the melee, the plane could have crashed and subsequently disappeared.
Why? Because Warfield believes that the pilot could have been suicidal.
He told the newspaper: "I combined my background in law enforcement and aviation and came up with, I believe, a plausible scenario.
"Little known to the public, in the cockpit next to the captain's seat is a very sharp fire axe.
"Once safely in cruise, Captain Shah programmed the turn into the flight computer, and after the co-pilot's hand-off with ATC he turned off the transponder and attacked the co-pilot with the fire axe."
In case this weren't abundantly clear already, we're well into the realms of pure speculation here.
What we do know is that the last recorded contact between the ground and the flight was around 40 minutes after take-off, at 12.14am.
It was near the Thai island of Phuket.
Satellite 'ping' signals continued for a few hours after that, but Mr Warfield said that the plane could have been without a pilot by this point and continued flying before running out of fuel and crashing into the vast ocean.
He continued: "The Captain had reengaged the autopilot manually immediately after the attack and before he passed out.
"The autopilot would continue to try to maintain altitude and rapidly put the B777 into a deep stall that would lead to a death spiral down in the ocean.
"This descent would take several minutes but would end in a catastrophic crash, disintegrating the B777."
That would have taken the flight up to the point where it is thought to have crashed, about 1,000 miles off the coast of Western Australia.
The problem still remains that no significant seabed wreckage has ever been found.
We might just never know what became of MH370.
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