The mystery surrounding flight MH370 has stirred up endless conspiracy theories from armchair investigators, aviation enthusiasts and industry experts.

PILOT SUICIDE

One of the earliest theories to surface following the plane’s disappearance was that Captain Zaharie Ahmad Shad deliberately steered the aircraft into the ocean. Leaked Malaysian police documents, first reported by New York magazine, alleged the pilot had flown a similar ‘suicide route’ on a home flight simulator. Media pounced on the idea the pilot was heartbroken. Malaysian police dismissed the theory.

The search for MH370: Why give hope when there was none?

HIJACK

A survey of air crash investigators by The Australian last year found the dominant theory to be that Captain Zaharie hijacked the aircraft and flew ‘it to the end’. The news outlet said the most likely scenario was that Zaharie locked the co-pilot out of the cockpit, killed all on board but himself by depressurising the plane, and then re-pressurised it to fly far into the southern Indian Ocean, glide it onto the water and sink it.

WATCH: MH370 ‘descended rapidly’

IS AMERICA HIDING SOMETHING?

Immediately following MH370’s disappearance in 2014, former Malaysian prime minister Mahathir Mohamad suggested the US was somehow involved when he wrote in a blog the Central Intelligence Agency was not sharing vital information. “Someone is hiding something,” he said. Later that year, speculation mounted further when a former French airline chief turned novelist accused America of shooting MH370 down because it feared it had been taken over by hackers and was about to be used in a terrorist attack.

A FIRE AND A HERO

Numerous speculators have concluded there was a fire on board. Some have suggested it was an electrical fire in the cockpit, others say it was a windscreen fire or an overheating of the landing gear. The fire would have caused the pilot to circle around and aim for an emergency landing at the nearest airport. But with little hope of a controlled landing, and with bustling cities and millions of people on all sides, Zaharie opted to plunge the aircraft into the ocean in a final heroic act.

A TOILET BREAK

One theory goes that something as simple as the pilot ducking out to the toilet was the cause of the crash. It goes like this: the captain steps out to stretch or go to the bathroom; there is a mechanical fault that causes a fast decompression of the cabin; the co-pilots activate oxygen, stabilise the aircraft and turn it back to Malaysia; the pilots then pass out before being able to make an emergency landing and fly off into the Indian Ocean, eventually running out of fuel.

N KOREA, RUSSIA, ALIENS

Wilder theories include North Korea taking down or snatching the aircraft; Russia falsifying the radar ‘pings’ of the plane and steering it towards Kazakhstan, and President Vladimir Putin knowing exactly where the crash site is. Five per cent of Americans surveyed by Reason.com believe the aircraft was abducted by aliens.