Passengers and crew of the missing Malaysia Airlines MH370 flight most likely died from suffocation as the plane coasted into the ocean on autopilot, Australian officials have said.
In a new 55-page report, the Australian Transport Safety Board said investigators arrived at the conclusion after comparing conditions on the flight with previous disasters.
The report narrowed down the possible final resting place from thousands of possible routes, while noting the absence of communications, the steady flight path and a number of other key abnormalities in the course of the ill-fated flight.
'Given these observations, the final stages of the unresponsive crew/hypoxia event type appeared to best fit the available evidence for the final period of MH370's flight when it was heading in a generally southerly direction,' the ATSB report said.
The new analysis comes more than 100 days after the plane disappeared on March 8 shortly after taking off from Kuala Lumpur bound for Beijing.
Investigators say what little evidence they have to work with suggests the plane was deliberately diverted thousands of kilometres from its scheduled route before eventually plunging into the Indian Ocean.
The next phase of the search is expected to start in August and take a year, covering some 60,000 sq km at a cost of A$60 million ($56 million) or more. The search is already the most expensive in aviation history.
The new priority search area is around 2,000km west of Perth, a stretch of isolated ocean frequently lashed by storm force winds and massive swells.
Two vessels, one Chinese and one from Dutch engineering company Fugro, are currently mapping the sea floor along the arc, where depths exceed 5,000 metres in parts.