MH370 vanished from the sky in 2014. Now Tony Abbott says it was 'mass murder-suicide'.

Former Prime Minister Tony Abbott says he was told “very early on” by Malaysian officials that the pilot of MH370 hijacked his own aircraft in an act of murder-suicide.

The Malaysian Airlines plane vanished on March 8, 2014, while flying from Kuala Lumpur. It was destined for Beijing, but contact was lost with the Boeing 777 over the South China Sea less than an hour after take-off.

Abbott, who was Prime Minister at the time, told Sky News Documentary MH370: The Untold Story he understood the Malaysian government quickly concluded that pilot Captain Zaharie Ahmad Shah had committed “mass murder-suicide”.

Tony Abbott on MH370: The Untold Story. Post continues below video.

“My understanding, my very clear understanding, from the very top levels of the Malaysian Government is that from very, very early on here they thought it was a murder-suicide by the pilot,” Abbott told Sky News.

“I’m not going to say who said what to whom, but let me reiterate – I want to be absolutely crystal clear – it was understood at the highest levels that this was almost certainly murder-suicide by the pilot.

“Mass murder-suicide by the pilot.”

Asked by interviewer Peter Stefanovic if that pointed to a potential cover-up, Abbott said he didn’t believe so.

“That’s not my assumption at all and I’ve read all these stories that the Malaysians allegedly didn’t want the murder-suicide plot theory pursued because they were embarrassed by one of their pilots doing this – I have no reason to accept that.”

MH370 was carrying 239 people, including six Australians and 153 Chinese nationals.

Following its disappearance, a multinational search effort began in the Gulf of Thailand and the South China Sea, where the aircraft's signal was last detected. Satellites then confirmed the plane went off course, flying south into the southern Indian Ocean for at least seven hours.

In June 2015, a piece of debris from the plane was found on Réunion Island, east of Madagascar. Other debris has been discovered washed up on Madagascar and along Africa's southern east coast. The bulk of the aircraft and its black box has not been located.

Ships and aircraft from Australia, China, India, Malaysia, New Zealand, South Korea, the United Kingdom and the United States were involved in the search of the southern Indian Ocean, and a six-month search by private US marine exploration company Ocean Infinity in 2018 also ended without success.

Two formal investigations - the 2017 official Australian Transport Safety Bureau report and the 2018 Malaysian Ministry of Transport report - failed to uncover what happened on the aircraft. The Malaysian report said there was no evidence Zaharie hijacked his own plane.

Abbott told Sky News in the two-part documentary officials never mentioned alternate theories, including a terrorist hijacking, a fire onboard or a mass hypoxia event.

He said if the investigation was limited because of the assumption the pilot was innocent, then it should be reopened.

"If it is a fact that the furthest reaches were not explored because of assumptions of a pilot who was no longer at the controls, I would say let’s ditch that assumption," Abbott said.

"Let’s assume that it was murder-suicide by the pilot, and if there is any part of that ocean that could have been reached on that basis that has not yet been explored, let’s get out and explore it."

The search for MH370 became the most expensive search in aviation history and has led to many theories, including conspiracies.

In the July 2019 issue of The Atlantic, writer and aviation specialist William Langewiesche noted the idea of "a pilot who runs amok" was hard to conceive, but it has happened before – with an EgyptAir flight in 1999 and Germanwings Flight 9525 in 2015.

Forensic examinations of the pilot’s simulator by the FBI also revealed Zaharie experimented with a flight profile that roughly matched what’s believed to have happened to MH370, which ended in "fuel exhaustion over the Indian Ocean".

Finding additional debris could be hard because the plane is believed to have gone into a "vicious spiral" before hitting the ocean and “disintegrated into confetti”.

Langewiesche said that instead of focusing on finding debris, he believed some of the key parts of the timeline of what happened could be revealed by what authorities in Malaysia are keeping quiet.

"Unless they are as incompetent as the air force and air traffic control, the Malaysian police know more than they have dared to say," Langewiesche wrote.

MH370: The Untold Story will air on Sky News at 8pm AEDT on Wednesday and Thursday.

Feature images: Getty and Sky News.