HONG KONG — Raw satellite transmission data from the vanished Malaysia Airlines Flight 370, released on 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 itself. 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 so-called electronic handshake.
“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, who lost his mother 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 based 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. These calculations have been 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 initially 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 on 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.
Conspiracy theorists have suggested that the plane flew west-southwest, perhaps to Diego Garcia, a British atoll in the middle of the Indian Ocean where the United States maintains a large military base. Mr. Farrar said that the raw data disproved that.
“That’s clearly not consistent with these arcs,” he said.
One question ahead of the publication of the raw data was whether it would provide valuable information about aircraft movements to intelligence agencies in China, North Korea and elsewhere, and possibly to terrorists as well. The raw data finally released covers transmissions from the aircraft, a series of so-called electronic handshakes, but does not include more sensitive information on how Inmarsat’s ground station in Perth, Australia, receives and records satellite transmissions.
Mr. Farrar said that differences among the satellite transmission terminals aboard various aircraft around the world meant that releasing the raw data from the aircraft would not necessarily make it possible for intelligence agencies or others to track flights elsewhere.
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 bathymetric survey has been completed, the bureau said, it could take a further 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.”
The satellite signaling, referred to as a handshake, was between an Inmarsat ground station in Perth, an Inmarsat satellite and the plane’s satellite communications system. For each transmission to the aircraft, the ground station recorded a “burst timing offset” and “burst frequency offset.”
The burst timing offset measures the time it takes for a transmission to make a round trip between the ground station, the satellite and the plane and then back. That allowed the authorities to calculate the distance between the satellite and the aircraft.
The burst frequency offset was used to help estimate the jet’s speed and direction. This offset measures the difference between the expected frequency of the transmission and the frequency received at the ground station.
The Chinese survey ship Zhu Kezhen has begun mapping the ocean floor and will be joined by a commercial vessel in June. Private contractors will later be involved in the specialized deep-sea search for debris on the ocean floor.
The safety bureau also noted that the suspected final location of the aircraft happened to intersect a flight corridor from the Cocos Islands to Perth. But the bureau seemed to play down the significance of this, only briefly mentioning that the site had a single flight route over it.
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.
Chinese relatives of Flight 370 passengers brushed aside a thin screen of police officers on March 25 and marched to the Malaysian Embassy in Beijing, where they threw plastic water bottles and yelled insults at the diplomats inside, in an incident that stirred a nationalistic backlash on Malaysian websites.