Investigators looking into the disappearance of Malaysia Airlines Flight 370 have concluded that the plane was probably not seriously damaged and remained in controlled flight until it ran out of fuel over the southern Indian Ocean.
Their conclusion, reached in the past few weeks, helped prompt the decision to move the search area hundreds of kilometres to the southwest.
The main evidence for the conclusion lies in a re-examination of Malaysian radar data from the flight and a more detailed analysis of electronic "handshakes" that the aircraft exchanged with an Inmarsat satellite over the Equator, senior officials involved in the investigation said. The altitude data from that tracking now appears to have been inaccurate, officials said.
Malaysian military radar tracked the Boeing 777-200 with 239 people aboard as it performed a U-turn over the Gulf of Thailand on March 8, flew across Peninsular Malaysia and the Strait of Malacca and disappeared at the north end of the Indonesian island of Sumatra.
Initial reports on the radar readings suggested that the plane soared to 13,700 metres, above its certified maximum altitude of 13,100 metres, then zoomed down low over the mountains of Peninsular Malaysia before climbing back to 7000 metres or more over the Strait of Malacca.
But a comprehensive international review of the data has concluded that the Malaysian radars had not been calibrated with enough precision to draw any conclusions about the altitude.
"The primary radar data pertaining to altitude is regarded as unreliable," said Angus Houston, the retired head of the Australian military who is now coordinating the search.
Martin Dolan, the chief commissioner of the Australian Transport Safety Bureau, agreed with Houston.
"There's nothing reliable about height," he said in an interview in his office here.
Houston and Dolan each said that the most reliable data came from the electronic handshakes. That data yields a series of six hourly arcs as the aircraft apparently headed south across the Indian Ocean, and a seventh arc based on a partial handshake as the engines appeared to run into difficulty.
The Australian government initially searched in the northeast corner of the seventh arc, partly because that location was consistent with an aircraft that was limping through the sky fairly slowly because it was damaged, or had burned a great deal of fuel in altitude changes, or both. The initial search was also set off by the detection of undersea sounds that were judged at first to be from the locator beacons of the plane's black boxes, although investigators later decided that was wrong.
- Sydney Morning Herald