THE pilot of flight MH370 soared to 40,000ft so his aircraft would depressurise and the passengers would slowly die of suffocation before he crashed it into the Indian Ocean, experts claim.

"Troubled and lonely" Captain Zaharie Ahmad Shah deliberately killed all 238 on board the Malaysian Airlines jet, according to the Independent Group that has worked on the case.

10 A new theory is that Captain Shah, left, either killed or incapacitated his co-pilot before depressurising the cabin to kill everyone on board

10

The body is made up of dedicated aviation sleuths and experts whose sole mission is to find out what happened to the doomed flight.

Members were even called into the help in the official search for the plane, which went missing on March 8, 2014.

They claim Shah steered the Boeing 777 off course before either waiting for the jet to run out of fuel or even deliberately nose-diving it into the water so it disintegrated on impact.

The new claims are revealed in The Atlantic by respected aviation expert William Langewiesche.

He suggests the most likely theory is that Shah either killed or incapacitated his co-pilot before depressurising the cabin to slowly kill everyone on board.

Electrical engineer Mike Exner - a member of the IG - believes Shah also made a steep climb to 40,000ft before the murder-suicide.

10 An image from a National Geographic documentary showing how the plane could have gone down Credit: National Geographic

10 The doomed flight went missing was en route from Kuala Lumpur to Beijing Credit: National Geographic

Climbing rapidly would have accelerated the depressurising process, he reveals.

"An intentional depressurisation would have been an obvious way - and probably the only way - to subdue a potentially unruly cabin in an airplane that was going to remain in flight for hours to come," adds Mr Langewiesche.

"In the cabin, the effect would have gone unnoticed but for the sudden appearance of the drop-down oxygen masks and perhaps the cabin crew's use of the few portable units of similar design.

"None of those cabin masks was intended for more than about 15 minutes of use during emergency descents to altitudes below 13,000 feet; they would have been of no value at all cruising at 40,000 feet.

"The cabin occupants would have become incapacitated within a couple of minutes, lost consciousness, and gently died without any choking or gasping for air."

MH370 was en route from Kuala Lumpur to Beijing with 239 people aboard March 8, 2014 and its disappearance remains one of the greatest mysteries in aviation history.

Many theories have been put forward including that veteran pilot Shah - who flew a similar path on his flight simulator at home - was depressed at the time.

10 Graphic showing the diverted flight path of the doomed MH370 jet

10 Only parts of the wreckage have been found - more than four years after the disaster Credit: Reuters

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.

There has been speculation the aircraft was depressurised by him, meaning all those on-board would have died of asphyxiation.

Mike Exner, a member of the Independent Group of investigators looking into the crash, has studied the radar data of the plane's movements in detail.

He told The Atlantic, the plane climbed to 40,000ft then made a sharp turn in order to accelerate the effects of decompression to incapacitate the passengers.

Oxygen masks designed to work at 13,000ft with just 15 minutes worth of supply would have been worthless.

Captain Shah would have had access to a separate supply allowing him to fly on for hours.

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.

MH370 - WHAT HAPPENED? Malaysia Airlines Flight MH370 took off from Kuala Lumpur and was heading to Beijing with 239 people on board. 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". Satellite "pings" from the aircraft suggest it continued flying for around seven hours when the fuel would have run out. Experts have calculated the most likely crash site around 1,000 miles west of Perth, Australia. But a huge search of the seabed failed to find any wreckage - and there are a number of alternative theories as to its fate.

An FBI inspection of the simulator found that he used it to recreate a flight roughly matching the path of MH370, ending in the Indian Ocean after running out of fuel.

The disappearance of the plane has attracted numerous wild conspiracy theories.

They include Vladimir Putin somehow being involved, it being flown to a secret location after it was hijacked, and it crashing in the Cambodian jungle.

If Shah did deliberately crash the plane, then it would mirror the actions of Germanwings pilot Andreas Lubitz.

Lubitz was a co-pilot for Germanwings, a regional airline owned by Lufthansa.

He locked Flight 9524's captain out of the cockpit and set the plane on a collision course with a mountain in the French Alps last year.

All 144 passengers and six crew members, including Lubitz, were killed.

According to an investigation Lubitz was being treated for a relapse of severe depression and suicidal tendencies but hid it from Germanwings.

There are currently no searches ongoing for MH370 though the Malaysian government has said it is open to proposals to resume the hunt.

The US firm Ocean Infinity mounted a "no cure, no fee" search for the plane in the southern Indian Ocean in January 2018 that ended in May without any clues.

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The firm said hopes to resume the search with better technology obtained in the past year. Scraps of aircraft debris have washed up on the east African coastline, but two underwater searches in the southern Indian Ocean proved fruitless, leaving few clues as to what happened. In July 2018, the Malaysian government’s report into the disappearance of Malaysia Airlines Flight 370 says all the evidence points to the fact the plane was deliberately flown out into the Indian Ocean.

10 The Boeing 777 was en route from Kuala Lumpur to Beijing when it disappeared Credit: Alamy

10 Captain Shah had problems with his marriage. it has been claimed Credit: Refer to Caption

10 Grace Subathirai Nathan, daughter of passenger Anne Daisy, shows a piece of debris believed to be from flight MH370 Credit: AFP or licensors

10 The captain would have been alone in the cockpit Credit: EPA

Families reveal new debris from the missing Malaysian Airlines flight MH370

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