MALAYSIA Airlines flight MH370 became one of the world's greatest aviation mysteries when it vanished without a trace back in March 2014.

After five years of theories about what happened to the passenger plane and where it is, we look at what the latest opinions are.

Malaysia Airlines flight MH370 went missing on March 8, 2014, with 239 passengers and crew on board Credit: Alamy

What happened to flight MH370?

Malaysia Airlines Flight MH370 took off from Kuala Lumpur and was heading to Beijing with 239 people on board - it never reached its destination.

Passengers included Chinese calligraphers, a couple on their way home to their young sons after a long-delayed honeymoon and a construction worker who hadn't been home in a year.

But at 12.14am on March 8, 2014, Malaysia Airlines lost contact with MH370 close to Phuket island in the Strait of Malacca.

Before that, Malaysian authorities believe the last words heard from the plane, from either the pilot or co-pilot, was "Good night Malaysian three seven zero".

Landing in the north

Early theories focused on the idea that the plane had flown north into central Asia.

Although this idea has been discredited it had some validity at the time due to the course military radar was tracking it on.

MH370 started on a north-east route, then turned and flew south-west and then turned again, heading north-west towards India.

The possibility of a northern landing was refuted by satellite company Inmarsat which owned the satellite which had been tracking it.

The idea was further discredited when parts of the plane were washed up off the coast of Africa.

'Mass hypoxia'

After debris from the plane was discovered on beaches across east Africa, it was concluded that the MH370 crashed somewhere in the south Indian Ocean near Western Australia.

This theory speculates there was some sort of accident or malfunction before the plane crashed, causing the plane to change direction in an attempt to find somewhere to land.

The accident then caused a "mass hypoxia event" - a sudden loss of oxygen - which knocked out the crew and passengers before they could land.

The plane would then continue on autopilot until it ran out of fuel.

This theory is favoured by the Malaysian government and the Australian Transport Safety Bureau (ATSB).

A deliberate act

There are numerous variations on this rather wild conspiracy theory but most centre on Captain Zaharie deliberately crashing the plane on purpose, or as part of some bizarre murder-suicide idea.

There has never been any proof that Zaharie diverted the plane on purpose.

His family said he "loved life" and had an unblemished flying record.

The latest variation on this idea was put forward by the Independent Group, who believe the pilot soared the flight to 40,000ft so the plane would depressurise and the passengers would slowly die of suffocation before he crashed it into the Indian Ocean.

'Priority zone'

The final report by the ATSB in 2017 put forward to theories.

The first just restated the unconscious pilot theory but added the plane had entered the water at a "high and increasing rate of descent", meaning it was free-falling.

The second was that a small new area, referred to as the "priority zone", was possibly the final location of the plane.

This area covering 25,000sq km was just to the north of where they had failed to find the plane in their own search.

Controlled ditching by conscious pilot

US company Ocean Infinity searched this "priority zone" in 2018 but found nothing and even searched further and further north but still failed to find MH370.

That failure to find anything triggered a rethink about what may have happened.

Some thought the pilot could have been conscious and performed a "controlled ditching" after gliding the plane for as long as possible.

If that was the case this would mean the plane could have come down around 200km further than had been assumed.

This has been rejected by the ATSB which pointed to data indicating the plane was in a "high and increasing rate of descent" in its final moments.

Mystery still surrounds why the passenger jet veered off course

Who were the pilot and co-pilot?

Malaysian captain Zaharie Amad Shah was flying MH370 when it disappeared.

Shah, born July 31, 1961, was described as a veteran pilot who joined Malaysia Airlines in 1981.

A father of three, passionate cook and keen fisherman, Shah lived with his wife in a luxury gated community where he was said to have built his own flight simulator.

In the wake of the plane's disappearance, rumours surfaced claiming his wife had moved out of their home.

The co-pilot was Fariq Abdul Hamid, 27, who was on his first flight on a 777 as a fully approved first officer.

He had flown five times before with a "check co-pilot" overseeing him.

But he had 2,763 hours experience flying other jets before moving to the larger aircraft.

Fariq was reportedly planning to marry his girlfriend.

2 A panel of aviation experts say the MH370’s disappearance was a deliberate act carried out by Captain Zaharie Amhad Shah Credit: Enterprise News and Pictures

What's the latest?

The captain of MH370 locked the co-pilot out of cockpit then crashed the plane in a murder-suicide, it has been reported.

The claim has been made by fellow pilot and life-long friend of Zaharie Ahmad Shah, 53, who was in command of the Boeing 777 the night it vanished.

Now, a fellow 777 captain has said he has reluctantly concluded that his close friend deliberately crashed the plane.

“It doesn’t make sense. It’s hard to reconcile with the man I knew. But it’s the necessary conclusion,” the unnamed pilot told The Atlantic.

As a senior officer and examiner it would have been easy to divert co-pilot Fariq Abdul Hamid, 27, out of the cockpit and then lock the door, the pilot said.

“All he had to say was ‘Go check something in the cabin,’ and the guy would have been gone,” he said.

The fellow pilot speculated that the mental state of Shah’s could have been a contributing factor to his decision.

“Zaharie’s marriage was bad. In the past he slept with some of the flight attendants,” he said.

Has the engine been found?

Five pieces, thought to be from the plane, recently washed up in Madagascar.

Aviation expert Victor Iannello believes one fragment, which appears to be from the interior floorboard, is consistent with a “high-speed impact".

More than 30 bits of aircraft debris have been collected from various places around the world but only three wing fragments that washed up along the Indian Ocean have been confirmed to be from MH370.

In October 2018, a sleuth claimed he'd spotted an engine in the Cambodian jungle.

Daniel Boyer previously claimed to have found the cockpit and tail, complete with Malaysia Airlines logo, of the missing aircraft.

Boyer told the Daily Star Online that the measurements of the blurry image matched those of the engine perfectly, being 4.3m wide and 2.7m in length.

most read in world news RAPE HELL Schoolgirl, 16, ‘gang-raped, killed and dumped to slowly die on building site’ GRINCHES Mum reveals HUGE Xmas gift haul for daughter - but some parents brand kid 'spoilt' 'TOUGH S**T' Lawyer refuses to scrap 'offensive' LGOPNR number plate.. can you work it out? Exclusive FLIGHTMARE Brit millionaire reveals harrowing moment his ear was 'BITTEN OFF' by plane yob DEATH RIDDLE Cops dig cemetery for sailor feared murdered by 'Frankenstein' serial killer MIRACLE RESCUE Moment man is rescued after drifting at sea for 3 days clinging to ice box

Boyer's discovery built off the work of Brit Ian Wilson, who first found what he thinks is an image of the plane on Google Maps.

However more recently, an MH370 sleuth has claimed that locals in Cambodia told him they saw a plane believed to be the doomed Malaysia Airlines flight crashing in the jungle.

And author Jeff Wise claims to have found proof the satellite communications systems was switched back on 40 minutes after it "went dark", complicating the mystery.