Raw satellite transmission data from the vanished Malaysia Airlines Flight 370, released Tuesday by the Malaysian government, provided further evidence that the plane crashed into the Indian Ocean after flying south and running out of fuel.
Malaysia and Inmarsat, the global satellite communications company, released the data after weeks of pressure from relatives of the mostly Chinese passengers and from the Chinese government. The Malaysian Department of Civil Aviation released the data as the country's prime minister, Najib Razak, was on his way to China for an official visit.
The final satellite transmission was an automated request from the aircraft for another "electronic handshake."
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"This is consistent with satellite communication equipment on the aircraft powering up following a power interruption," the Australian Transport Safety Bureau said in a separate statement. "The interruption in electrical supply may have been caused by fuel exhaustion."
One of the Chinese relatives, Wang Le, whose mother was on the plane, was unimpressed with the release of the data. "What help will publicizing this data provide toward finding the airplane?" he asked. "This kind of data is too technical for family members. We cannot understand it and we also don't know whether it's real or fake."
Tim Farrar, a satellite communications consultant in Menlo Park, Calif., said that the raw data appeared to support calculations, by Inmarsat and by governments involved in the search, that the missing plane, a Boeing 777-200, had crashed into the eastern Indian Ocean.
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These calculations have determined that the lost plane turned south after it did a U-turn over the Gulf of Thailand, flew west across Peninsular Malaysia and then disappeared from radar just north of the Indonesian island of Sumatra.
When Inmarsat and government agencies realized that the plane kept flying for six hours after its communications gear was turned off over the Gulf of Thailand, they suggested arcs of possible locations for the aircraft either to the north in Central Asia or to the south in the eastern Indian Ocean.
But the data released Tuesday showed that small changes in the position of Inmarsat's satellite relative to the Earth meant that the plane must have flown south, not north, Mr. Farrar said.
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In a series of statements released late Monday, the Australian Transport Safety Bureau said the mapping of the ocean floor, already underway, would take at least three months to complete, in water that could be as deep as 20,000 feet. Once this survey of ocean depths had been completed, the bureau said, it could take a year to finish the deep-sea search of the ocean floor for debris from the Boeing 777.
The bureau's chief commissioner, Martin Dolan, said that the complexities surrounding the search "cannot be underestimated," but that he remained "confident of finding the aircraft."
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The satellite signaling, referred to as a handshake, was between an Inmarsat ground station in Perth, Australia, an Inmarsat satellite and the plane's satellite communications system. Diplomatic relations between Malaysia and China have been strained since the loss of Flight 370. Chinese officials and particularly the Chinese state news media have been critical of Malaysia's efforts to find the plane, and Chinese tourism to Malaysia has dropped by a third in the past two months.