Malaysia Airlines flight MH370 was almost certainly on autopilot when it ran out of fuel and crashed, Australian officials said on Thursday as they announced their search will shift further south.
Investigators have been grappling with the mystery of the jet's disappearance on March 8 with 239 people on board, with months spent scouring the Indian Ocean and finding nothing.
An expert group has reviewed all the existing information and Australian deputy prime minister Warren Truss said it was now "highly, highly likely that the aircraft was on autopilot" when it went down.
"Otherwise it could not have followed the orderly path that has been identified through the satellite sightings," he told reporters.
Martin Dolan, commissioner of the Australian Transport Safety Bureau, which is leading the search, agreed.
"Certainly for its path across the Indian Ocean we are confident that the aircraft was operating on autopilot until it went out of fuel," he said.
The plane was flying from Kuala Lumpur to Beijing when it vanished, shocking the world and shattering families of those aboard, who still have no idea what happened to their loved ones.
No trace of it has been found despite an extensive Australian-led search effort deep in the Indian Ocean, where Malaysia believes it crashed.
Theories on what happened include a hijacking, rogue pilot action or mechanical failure.
A review of the data has now identified a new area, covering up to 60,000 square kilometres in the southern Indian Ocean, where an underwater search will start in August and take up to 12 months.
"Specialists have analysed satellite communications information -- information which was never initially intended to have the capability to track an aircraft -- and performed extremely complex calculations," Truss said.
"The new priority area is still focused on the seventh arc where the aircraft last communicated with satellites.
"We are now shifting our attention to an area further south along the arc based on these calculations."
The new area is around 1,800 kilometres (1,100 miles) west of Perth and had previously been subject to an aerial search, which found no debris.
Truss said he was "optimistic" that "this site is the best available and most likely place where the aircraft is resting".
Until now, the most intensive search had been with a mini-submarine in an area further north, where pings believed to be from the plane's black box were detected.
The area has now been ruled out as the final resting place of MH370. The source of the noises is unknown.