The Malaysia Airlines plane missing since March 8 was on autopilot before it possibly spiraled into the southern Indian Ocean, Australian officials said today as they announced the latest shift in the search for the doomed airliner.
After analyzing data between the plane and a satellite, officials believe Flight 370 was on autopilot the entire time it was flying across a vast expanse of the southern Indian Ocean until it ran out of fuel, Australian Transport Safety Bureau chief commissioner Martin Dolan said.
"Certainly for its path across the Indian Ocean, we are confident that the aircraft was operating on autopilot until it ran out of fuel," Dolan told reporters in Canberra.
The assumption is that the autopilot was manually switched on, rather than activated automatically under a default setting, Dolan said. Authorities still aren't sure when the Boeing 777 began running on autopilot.
The new search area for the plane, which went missing on a flight from Kuala Lumpur to Beijing, covers more than 23,000 square miles, which is 70 times larger than the area that has already been searched.
Confusion surrounding the plane's descent contributed to the expanded search area. The jetliner could have spiraled out of control for nearly four minutes before crashing, according to today's report.
Based on the logs of communication between the Boeing 777 and the aviation service satellite network Inmarsat, the wayward jetliner flew for seven hours and 38 minutes before running out of fuel. But when an airliner's fuel tanks run empty, the engines are not likely to stop at the same time, the report explains.
That uneven power likely caused an uncontrolled, spiral descent.
Dolan stressed that his agency is not speculating on what caused the plane to go missing in the first place. The Malaysian government is handling that task.
"Questions as to why, are not what we needed to address to refine the search area," Dolan said.
The 58-page report released today is intended to explain the various ways the plane might have flown to predict where it wound up in the ocean. Such predictions provide some reasonable search boundaries after lengthy, expensive and, so far, unsuccessful previous searches by air and sea.
The report does suggest that one particular scenario, an incapacitated cockpit crew suffering from the effects of hypoxia, is the "best fit" for the available evidence for the final period of the flight because, like MH 370, previous accidents resulting from a loss of aircraft pressurization also resulted in a loss of radio communication, a long period without any maneuvering of the airplane and a steady cruise and descent with fuel exhaustion.
In looking for parallel events that might be helpful, the Australian Transport Safety Bureau reviewed past air accidents, including 22 in-flight upsets, four flights in which the pilots were unresponsive at the controls and an equal number of air accidents that involved the airplane gliding to the ground. Data from those accidents was examined to determine how the airplane reacted after the initial event, how it descended and impacted the ground or water, and how far the debris scattered.
By creating a framework of possible scenarios, the ATSB - along with Boeing, Inmarsat and safety investigators from the United Kingdom and the United States - created a mathematical database that they are using to suggest where the plane entered the water.
Some 1,000 scenarios were considered in creating the refined search zone. Before the hunt resumes again, however, two ships will complete a bathymetric survey of the ocean floor that began last month in order to create a more detailed map of the underwater terrain.
Using probabilities, Dolan said that there was a 1 to 5 percent chance that the ships might discover the wreckage of MH 370 during the mapping process.
The Associated Press contributed to this report.