INVESTIGATORS searching for the wreckage of Malaysia Airlines flight MH370 are reportedly preparing to revive theories that the plane may have been brought down deliberately.
The Australian Transport Safety Bureau (ATSB) has been conducting its search of a 46,000 square mile area of the Indian Ocean on the assumption that the aircraft crashed when its fuel ran out after cruising on autopilot as a "ghost flight" with the pilots incapacitated or dead.
That sequence of events is supported by data from Boeing and the British Inmarsat satellite communications firm but failure to find further wreckage will cast significant doubt.
The AUD$180 million search, which has been the most expensive in aviation history, will end in 10 weeks and passengers' families are demanding answers.
"We're not at the point yet, but sooner or later we will be - and we will have to explain to governments what the alternative is," chief commissioner of the ATSB, told The Times.
"And the alternative is, frankly, that despite all the evidence as we currently have the possibility that someone was at the controls of that aircraft on the flight and gliding it becomes a more significant possibility, if we eliminate all of the current search area.
"In a few months time, if we haven't found it, then we'll have to be contemplating that one of the much less likely scenarios ends up being more prominent. Which is that there were control inputs into that aircraft at the end of its flight."
Had a pilot or hijacker been in control of the Boeing 777 when it went off course on 8 March 2014, on its way from Kuala Lumpur to Beijing, the area of ocean where it may have crashed is far larger.
The ATSB did not immediately reply to the Independent's request for a comment on the investigation's progress.
Australian investigators are only responsible for assisting search efforts for MH370, while the Malaysian government is working to establish why the plane disappeared.
"For search purposes, the relevant facts and analysis most closely match a scenario in which there was no pilot intervening in the latter stages of the flight," the ATSB said last month.
"The ATSB has neither the authority under international agreements nor the need for the purposes of its search to make statements about why the aircraft disappeared."
A wing flaperon discovered in July on the island of Reunion, in the Indian Ocean, is still being analysed by French judicial authorities.
A Chinese ship, the Dong Hai Jiu 101, was due to depart from Australia on Thursday to comb the Indian Ocean with state-of-the-art sonar equipment.
More than 32,800 square miles of the search area have been scoured since late 2014, with Australia and Malaysia sharing the cost.
Most of MH370's 239 passengers and crew were Chinese, while Malaysians, Australians and citizens of 12 other countries were also on board.
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