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.

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 has been completed, the bureau said, it can 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.”

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.