A Canadian aviation expert and former airplane crash investigator says he can state with "100 per cent certainty" that Malaysian Airlines Flight 370 was intentionally ditched in the ocean by one of the pilots in an act of murder-suicide.

"This is a criminal event. It's not an accident," Larry Vance, a former investigator with the Transportation Safety Board of Canada, told CBC News in a phone interview.

"This was planned and conducted, carried out by one individual who had control of the airplane via his job to have control of the airplane," Vance said.

Either the pilot or co-pilot made the decision, "for whatever reason, to take it to a remote part of the ocean and make it disappear forever."

Many theories have circulated about the fate of the plane, with some believing it may have been hijacked or shot down, but Vance says his examination of some wreckage that was eventually found shows the plane was deliberately landed in the ocean.

Vance spent 18 months researching and writing his soon-to-be released book MH370 Mystery Solved. He was not part of the official investigation conducted by the Australian Transport Safety Bureau.

He teaches courses in accident investigation and used the crash as course material. From there, he said, he and a few of his colleagues began to look at some of the details of the evidence that was available.

'Murder suicide'

Vance was also part of a group of international aviation experts who recently appeared on 60 Minutes Australia to share their conclusions that the crash was an intentional act.

"It would certainly fit to call it a murder suicide," he said.

This view contradicts a report put out in 2016 by the ATSB, which concluded that the plane ran out of fuel and crashed into the ocean during a high-speed descent. It was the bureau's belief that the plane had been flying on auto pilot or without pilot input.

The Boeing 777 carrying 239 people took off from Kuala Lumpur at 12:41 a.m. local time on March 8, 2014, destined for Beijing.

According to the Malaysian government, the final voice transmission received by controllers at Kuala Lumpur's international airport at 1:19 a.m. local time on March 8 was "Good night Malaysian three-seven-zero."

Former airplane crash investigator Larry Vance says Malaysian Airlines Flight 370 was intentionally ditched in the ocean by one of the pilots in an act of murder-suicide. (Larry Vance)

After 40 minutes of flight time, the plane disappeared from radar, as the plane's transponder stopped transmitting.

Malaysian military radar later identified the plane way off course, in the northern part of the Strait of Malacca. A satellite, however, picked up seven signals, or "pings" over the next hours. This led investigators to conclude the plane flew another six hours, south to the Indian Ocean.

The plane has never been found, but pieces of wreckage have floated to the shores of eastern Africa.

Vance and his team examined detailed photographs of some of the wreckage and concluded the plane was deliberately crashed. Their belief was based on two pieces of wreckage from the flap system on the right wing of the airplane — the flaperon, and the section of flap that's next to it.

By examining the marks on the wreckage, they theorized that the flaps had been down when the airplane hit the water. This would mean that the plane had entered the water at a relatively low speed.

"We would call that a controlled ditching into the water. And the only way that could happen is if somebody was flying the airplane. In particular, if somebody selected the flaps to be in the extended position."

A book by retired Canadian investigator Larry Vance claims the pilot of Malaysia Airlines Flight 370 deliberately crashed into the Indian Ocean in an apparent pre-planned mass murder-suicide. It contradicts the theory of Australian air safety investigators, who believe the jet crashed into the water after it ran out of fuel, its pilots incapacitated. 3:55

And if the flaps were extended, it meant the engines were still running and that the plane had not run out of fuel.

"I believe with 100 per cent certainty that the airplane entered the water in a controlled ditching with the flaps extended," said Vance.

The plane was piloted by Capt. Zaharie Ahmad Shah and 1st Officer Fariq Ab Hamid.

Vance said he can't say for certain if the pilot or co-pilot was the perpetrator, although it's his belief that it's more likely Shah was responsible because he had ordered two extra hours of fuel.

Turned off transponder

It was Shah, he believes, who turned off the transponder to make the airplane disappear from radar, and then turned off the lights in the passenger cabin and depressurized the airplane.

"And that's just one switch, he can flick one switch and the airplane is depressurized."

This would render the passengers unconscious and they would have died quickly from lack of oxygen, he said.

During that small window of time, Vance believes, Shah somehow eliminated the co-pilot. He may have made up some reason to get the co-pilot out of the cockpit and then locked the door, leaving him to die from the lack of oxygen in the passenger cabin. Or, Vance said, "He eliminated him in the cockpit."

The pilots have oxygen supplies that can last for hours. But after he depressurized the plane, it would have been very easy for the pilot to repressurize the airplane, Vance said.

The ship Ocean Shield detected underwater sounds, reported to be consistent with pings from aircraft black boxes, roughly 600 kilometres away from where a Chinese ship earlier reported hearing faint signals. This map is based on information provided by the Joint Agency Co-ordination Centre. (CBC)

Vance believes that after flying another six hours, the pilot made a controlled ditch to ensure there would not be massive amounts of wreckage, and instead, the plane would sink to the bottom of the ocean.

"My contention is that he had a destination in mind, he took it to that destination," he said. "He took an airplane and made it disappear so that nobody could ever find where it went and nobody would find it ever."

Vance's conclusions challenged

​Martin Dolan, former head of the Australian Transport Safety Bureau who appeared with Vance on the 60 Minutes episode, challenged Vance's certainty on his conclusions.

"The evidence is not yet sufficient to draw as firm a conclusion as you appear to have done," Dolan said.

Dolan, who led the search for the missing plane, said there are two viable theories — that someone was in control of the flight when it crashed, "or they were not."

"There's evidence that supports both of those theories," he said.

It's only speculation that the flaps were down and that the plane did not run out of fuel, he said.

But Vance disagrees and believes the official investigators were not experienced enough to see the evidence on the pieces of wreckage .

"I think they got wedded to a theory."

As for the motive of the perpetrator, Vance said that's not his area of expertise.

"People who are specialists in human behaviour and psychology and those sorts of things can answer that."

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