Missing Malaysian Jet's Crew Was Probably Unresponsive, Officials Say

Canberra: The missing Malaysia Airlines jet 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 of Flight 370 was unresponsive, possibly suffering from the effects of oxygen deprivation, Australian officials said Thursday 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 the most likely scenario as the Boeing 777-200 headed south across the Indian Ocean on March 8 was that the crew was suffering from hypoxia or was unresponsive for another reason.

Hypoxia occurs when a plane loses air pressure and the pilots, lacking adequate oxygen, become confused and incapable of performing even basic manual tasks.

Pilots are trained to put on oxygen masks immediately if an aircraft suffers depressurization; 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 the Malaysian Peninsula and then headed northwest across the Strait of Malacca before turning south. It is believed to have crashed somewhere in the southern Indian Ocean off the western coast of Australia, which has been coordinating the search.

Evidence for an unresponsive crew as the plane flew south includes the loss of radio communications, a long period with no maneuvering 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 no 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 some investigators still leaned toward the possibility that one of the pilots deliberately flew the plane to the southern Indian Ocean in a suicide mission that also killed everyone else on the plane.

Advocates of the hypoxia theory argue that pilot suicide cases tend 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 it would be highly unusual for a suicidal person to proceed with such a deadly plan over many hours, investigators said.

Depressurization 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 Thursday, Martin Dolan, the chief commissioner of the Australian Transport Safety Bureau, said someone on the plane had put it on autopilot, but he declined to speculate as to 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 23,000 square miles. Up to three deep-sea submersibles will be used for the yearlong endeavor, starting in August.

By comparison, a fruitless search of ocean floor farther to the northeast by a U.S. 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, covered only 332 square miles.

That area was chosen based on the supposition that the plane, 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 traveled on a straight course under full control of the 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.

Angus Houston, the retired head of the Australian military who is overseeing the country's search, said in an interview earlier this month that he assumed that the flight had been on autopilot even if a conscious pilot were at the controls. That is because a Boeing 777 is a very difficult plane to fly manually.

Two deep-sea survey vessels, one contracted by Australia and the other sent by China, have already begun mapping the ocean floor in the new search area, looking for undersea mountains and hills that could wreck a submersible if it is towed into one. Dolan said that the three-month mapping project was not designed to detect aircraft debris, and that there was a less than 5 percent chance that it would do so.

The midpoint of the new search area is 1,100 miles west-northwest of Perth, Australia. The Fugro Equator, the vessel under contract by Australia, is already mapping at the near end of the new search area, about 1,000 miles northwest of Perth.

The new search area runs 400 miles along the so-called seventh arc of possible locations for the aircraft, based on the seventh and last electronic handshake that it had with the satellite. The area has a width of only 58 miles, on the assumption that the plane was on autopilot and quickly stalled and crashed when it ran out of fuel.

If a conscious pilot were at the controls, the aircraft might have glided up to 100 miles further. At the news conference Thursday, held in the Blue Room of Australia's Parliament House, Truss and Dolan said a much wider area of the ocean floor had a low-probability chance of being the final resting place of Flight 370 but there were no immediate plans to search that wider area.

Aircraft and ships searched the new search area for floating debris on the 21st through 26th days after the plane disappeared, and found nothing.

Tim Farrar, a satellite communications consultant in Menlo Park, California, one of a group of satellite experts who have been independently analyzing clues to Flight 370's disappearance, said in a telephone interview that assuming that the plane was on autopilot simplified the search and reduced the range of places along the seventh arc where the plane might have come to rest. But he cautioned that a conscious pilot still might have been at the controls while leaving the flight on autopilot.

The report showed many computer simulations, a few of them including flights far to the east or west of the new search zone. Dolan declined to say what percentage of the computer simulation results showed the aircraft ending up within the new search area.

Farrar cautioned that the new search might not find the plane either. "

It wouldn't surprise me if there's a reasonable probability it's outside the defined search area," he said. "It's going to be a difficult search."