A new theory suggesting passengers on the MH370 are actually alive and being held captive is “very highly unlikely” to  come to fruition, an Australian aviation expert has said.

Families of 154 Chinese passengers onboard the Malaysia Airlines plane issued a statement earlier this week, questioning official investigations that suggested those onboard had perished.

Instead, they said they believed they were alive and being held captive.

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They also raised concerns with findings that confirmed a plane part that washed up on an island in the Indian Ocean was from the MH370.

“There is no real proof justifying any of these statements,” the statement read.

“In the absence of proof to the contrary, we believe it is possible the missing may still be alive.

“If this is so, we would willingly grant to the perpetrators amnesty in return for the release of the missing.”

The flaperon was discovered in July on Reunion Island. Photo: EPA

But CQ University aviation senior lecturer Ron Bishop said it was “very highly unlikely” those onboard had survived.

“Especially since we have found some parts that match up to that type of aircraft, I would say it is very highly unlikely,” he told The New Daily.

“Is there a remote chance? Maybe, but it is very unlikely.

“Plus that is a lot of people to hold at once, and it is not a small aircraft to land and to be able to hide.”

Officially, the presumption is that those onboard perished, a stance supported by local authorities.

A spokesman for the Joint Agency Coordination Centre, the Australian body coordinating local search efforts, noted that in January 2015 the Malaysian government declared the disappearance an “accident” and that all onboard “were presumed to have lost their lives”.

In a statement to The New Daily, the spokesman also said the current search area was carefully calculated.

“Theories suggesting the aircraft is located anywhere other than in the southern Indian Ocean are not supported by known facts or careful analysis,” he said.

‘It would need a large airport’

Street art in Malaysia expresses victims’ grief. Photo: Getty

Mr Bishop said the plane would need a large runway, probably at least 2.5km long, to land and a huge hangar – “it would basically be a large airport”.

But it was the recovery of a flaperon, a wing part, in July that was later confirmed to be part of the plane, that seemed to prove the plane had crashed.

“The thing that is very hard for us, is to find where a large part of it is (like the fuselage),” he said.

“We haven’t found that yet and that is because it is a very large ocean, it is very sad for the families but it is looking like it is probably unlikely that they are being held captive.

“If [the fuselage] remained intact on landing and the pieces broke up after landing that would support it being hard to find because that piece may have sunk fairly quickly, but even if it took a while it would eventually sink and take down any evidence with it.”

Between fantasy and reality

Families of the victims in the MH370 crash have said they have been in agony since their loved ones disappeared. Photo: Getty

It has been an agonising wait for the families of those on the MH370, with very few concrete answers available.

University of New England missing persons researcher Sarah Wayland said the lack of firm evidence enhanced the grief of loved ones.

“When people live in those two spaces (not knowing if a loved on is alive or deceased), there is room for lots of different fantasy thoughts, but also reality thoughts,” she told The New Daily.

“When we hear stories of people being located after long periods of time, that adds to the multitude of stories families of missing people can engage in, in terms of what happened to the person, because there is no certainty.”

Although official reports presumed the missing passengers to be dead, Ms Wayland said it was important to respect the families’ wishes.

“The reality is strange things do happen in the universe, I’m not saying we should hold on to fantasy ideas of hope, but if we don’t have all the pieces of the puzzle there is always going to be the potential for families to be drifting between hopefulness and hopelessness,” she said.