A Royal New Zealand Air Force pilot during a search for the missing MH370 plane near Perth. (AFP)
Canberra, June 26: Malaysia Airlines’ missing Flight 370 appears to have been on autopilot as it flew south across the Indian Ocean until running out of fuel, and the likeliest scenario is that the crew was unresponsive, possibly suffering from the effects of oxygen deprivation, Australian officials said today in announcing a new deep-sea search for the aircraft.
A report issued by the Australian Transport Safety Bureau, outlining how the new search zone had been chosen, said that the most likely scenario as the aircraft headed south across the Indian Ocean on March 8 was that the crew was suffering from hypoxia or was otherwise unresponsive.
Hypoxia occurs when a plane loses air pressure and the pilots, lacking adequate oxygen, become confused.
Pilots are trained to put on oxygen masks immediately if an aircraft suffers depressurisation; their masks have an hour’s air supply, compared with only a few minutes for the passengers. The plane, which left Kuala Lumpur, Malaysia, bound for Beijing, with 239 people aboard, made its turn south toward the Indian Ocean about an hour after it stopped responding to air-traffic controllers.
The crew stopped communicating while the aircraft was over the Gulf of Thailand. The plane then did a U-turn, crossed Peninsular Malaysia and then headed northwest across the Strait of Malacca, before later turning south.
Evidence for an unresponsive crew as the plane flew south includes the loss of radio communications, a long period with no manoeuvering of the aircraft, a steadily maintained cruise altitude and eventual fuel exhaustion and descent, the report said.
“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 document said. The report added that this was an operating assumption for the search and that it was not meant to infringe on Malaysia’s authority as the government responsible for conclusively identifying a cause for the loss of the plane.
There is not a consensus among investigators, even within the Australian government, on the hypoxia or unresponsive crew theory. Other officials, who insisted on anonymity because of the diplomatic sensitivity of the issue with Malaysia and China — most of the flight’s passengers were Chinese — said that some investigators still leaned towards the possibility that one of the pilots deliberately flew the plane to the southern Indian Ocean in a suicide that also killed everyone else on the plane.
Advocates of the hypoxia theory argue that pilot suicide cases have tended to involve pilots who crashed their planes suddenly, not after hours of flight. A clinical psychologist advising the investigation has been very skeptical of the suicide theory, saying that it would be highly unusual for a suicidal person to proceed with such a deadly plan over many hours, investigators said.
Depressurisation of an aircraft can occur from mechanical failure, an attempted hijacking or many other causes. The Australian report did not speculate on why the crew might have succumbed to hypoxia or otherwise become unresponsive.
At a news conference here today, Martin Dolan, the chief commissioner of the Australian Transport Safety Bureau, said that someone on the plane had put it on autopilot, but he declined to speculate on who might have done so and why. “If the autopilot is operational, it’s because it has been switched on,” Dolan said.
Based on recent analysis of data from electronic “handshakes” between the plane and a satellite operated by the company Inmarsat, the Boeing 777-200 appears to have followed a straight track to the south after making a left turn somewhere west of the northern tip of the Indonesian island of Sumatra, Dolan added.
Warren Truss, the deputy Prime Minister of Australia and also the minister for infrastructure and regional development, said at the news conference with Dolan that Australia planned to hire a contractor to scour a rectangular area of ocean floor covering 60,000 sq km, or 23,000 square miles.
By comparison, a fruitless search of ocean floor farther to the northeast by a US Navy contractor in late April and May, following the detection of acoustic pings initially believed to have been from the aircraft’s so-called black boxes, only covered 860 sq km.
That area was chosen based on the supposition that the plane might have been limping along at reduced speed, had burned a great deal of fuel in extreme altitude changes or had been zigzagging somewhere along its course. But the new conclusion, that the aircraft travelled on a straight course under autopilot, does little to erase the mystery of why the plane ever departed from what was supposed to have been a routine red-eye flight from Kuala Lumpur to Beijing.