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Flight 370 Believed to Be on Autopilot
Flight 370 Believed to Be on Autopilot
Australian authorities have shifted the search for Malaysia Airlines Flight 370 further south in the Indian Ocean and said they believed that the plane was on autopilot.
Publish Date June 26, 2014
Credit Alan Porritt/European Pressphoto Agency
CANBERRA, Australia â Nearly four months after Malaysia Airlines Flight 370 vanished into the night, Australian transportation officials said in a report on Thursday that the plane kept flying until it ran out of fuel, most likely because the cockpit crew had become unresponsive because of oxygen deprivation.
The plane appears to have flown in a straight line south across the Indian Ocean, controlled entirely by the autopilot, Australian officials said. But they avoided offering hypotheses for why the plane had reached the northern end of the Indonesian island of Sumatra and had turned south in the first place, when it was supposed to travel the night of March 8 from Kuala Lumpur, the Malaysian capital, to Beijing.
Malaysian radar records show that the Boeing 777-200 did a U-turn over the Gulf of Thailand instead, then banked right across the Malaysian Peninsula and then banked right again to reach the northern tip of Sumatra.
Evidence of an unresponsive crew as the plane flew south for more than five hours includes the loss of radio communications, a long period with no maneuvering of the aircraft, a steady cruise altitude and eventual fuel exhaustion and descent, the report said. It added that this could have been caused by hypoxia, or oxygen deprivation, among the cockpit crew.
Reconstructing the Planeâs Path
The main communications systems of the Malaysia Airlines plane ceased working about 40 minutes into the flight, forcing investigators to try to piece together the planeâs location from other systems.
Secondary Radar and Text Updates
Air traffic controllers typically know a plane’s location based on what is called secondary radar, which requests information from the plane’s transponder. A plane also uses radio or satellite signals to send regular updates through Acars, the Aircraft Communications Addressing and Reporting System. Both of those systems were turned off.
Two Malaysian military radar stations tracked a plane using primary radar, which sends out radio signals and listens for echoes that bounce off objects in the sky. Primary radar does not require a plane to have a working transponder.
If Acars updates are turned off, the plane still sends a “keep-alive” signal, that can be received by satellites. The signal does not indicate location, but it can help to narrow down the plane’s position. A satellite picked up six complete signals and a seventh partial, about one per hour, after it left the range of military radar.
âGiven these observations, the final stages of the unresponsive crew/hypoxia event type appeared to best fit the available evidence for the final period of MH370âs flight when it was heading in a generally southerly direction,â the document said.
Hypoxia occurs when a plane loses air pressure and the pilots, lacking adequate oxygen, become confused and incapable of performing even basic manual tasks, though they continue to feel confident in their own abilities.
Pilots are trained to put on oxygen masks immediately if an aircraft suffers depressurization; their masks have only an hourâs air supply, however. The plane, with 239 people aboard, made its turn south toward the Indian Ocean about an hour after it stopped responding to air traffic controllers. It is believed to have crashed somewhere in the southern Indian Ocean off the western coast of Australia. Australian officials have been coordinating the search.
Passengersâ masks have only a few minutes of oxygen, based on the theory that the pilot of a troubled plane will quickly descend to an altitude at which there is little need for a supplemental air supply.
The report added that the theory of an unresponsive crew possibly suffering from hypoxia was an operating assumption for the search and was not meant to infringe on Malaysiaâs 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. Angus Houston, the retired head of the Australian military who is overseeing the countryâs search, said in a telephone interview this month that he assumed that the flight had been on autopilot even if a conscious pilot had been at the controls. That is because a Boeing 777 is a very difficult plane to fly manually.
Other officials, who insisted on anonymity because of the diplomatic sensitivity of the issue with Malaysia and China â most of the flightâs passengers were Chinese â 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 aboard.
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. If a plane undergoes gradual depressurization, pilots do not necessarily notice that they are losing oxygen, and with it, their mental clarity. Masks are supposed to deploy automatically with a loss of air pressure, but they need to be fitted properly for a full flow of oxygen.
Tracking Flight 370
The sequence of events known by the authorities, in local times.
At a news conference here on Thursday afternoon, 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. âIf the autopilot is operational, itâs because it has been switched on,â Mr. Dolan said.
Based on recent analysis of data from electronic âhandshakesâ 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, Mr. Dolan added.
Warren Truss, the deputy prime minister of Australia and also the minister for infrastructure and regional development, said at the news conference 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 500 miles farther to the northeast by a United States Navy contractor in late April and May, after the detection of acoustic pings initially believed to have been from the aircraftâs so-called black boxes, covered only 332 square miles.
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 to Australia, about 960 miles northwest of Perth.
The new search area runs 400 miles along the âseventh arcâ 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.
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, Calif., one of a group of satellite experts who have been independently analyzing clues to Flight 370âs 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 the electronic handshakes could also be compatible with stable flight controlled by a human pilot. He questioned whether the report or Australian officials had enough information to justify their assumption that the plane was being controlled entirely by autopilot.
Mr. Farrar said that the new search might not find the plane either. âIt wouldnât surprise me if thereâs a reasonable probability itâs outside the defined search area,â he said. âItâs going to be a difficult search.â
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