'MH370 Was Under Control Until Crash'

CANBERRA, Australia: Investigators have concluded that Malaysia Airlines Flight 370, which veered off course and disappeared on March 8, was probably not seriously damaged in the air and remained in controlled flight for hours after contact with it was lost, 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 focus of the search hundreds of miles to the southwest.

The main evidence for the conclusion lies in a re-examination of Malaysian military radar data and in a more detailed analysis of electronic "handshakes," or pings, that the aircraft exchanged with an Inmarsat satellite over the Equator, senior officials involved in the investigation said. The altitude readings from the radar now appear to have been inaccurate, officials said.

The radar tracked the aircraft, a Boeing 777-200 with 239 people aboard, as it turned sharply off its scheduled northeastward flight path over the Gulf of Thailand and flew west across Peninsular Malaysia and the Strait of Malacca. The plane then passed beyond radar range near the northern tip of the Indonesian island of Sumatra. Initial reports about the radar readings suggested that along the way, the plane soared as high as 45,000 feet, above its certified maximum altitude of 43,100 feet, and then zoomed down low over the mountains of Malaysia before climbing back to 23,000 feet or higher over the Strait of Malacca.

But a comprehensive international review has found that the Malaysian radar equipment had not been calibrated with enough precision to draw any conclusions about the aircraft's true 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.

Houston said in a telephone interview that it was clearly possible that at some point during the tracked part of the flight, the plane flew at 23,000 feet. But he said he doubted whether anyone could prove that the plane had soared and swooped the way the initial reports suggested.

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 in the Australian capital. Radar systems generally give accurate readings of an aircraft's location, speed and direction without difficulty. Many military radar systems can also detect altitude, but in order to yield reliable readings, the equipment must be regularly and carefully recalibrated to fit local atmospheric conditions.

Houston and Dolan declined to discuss any details about the Malaysian radar readings, nor would they speculate about why the missing plane would have been in controlled flight across the Indian Ocean.

Other officials involved in the crash investigation have suggested that either of the plane's pilots might have commandeered the aircraft in order to commit suicide, or that a smoke from a fire in the fuselage might have overcome the pilots and passengers but left the engines and autopilot working normally.

Some investigators are convinced that one of the pilots was involved, saying that no credible evidence has appeared for another explanation. But others say that the evidence suggesting pilot involvement is inconclusive and contradictory. Hishammuddin Hussein, Malaysia's defense minister and acting transport minister, publicly denied British and Australian news reports on Monday that the pilot had been identified as the prime suspect.

If the plane did not soar and swoop, but maintained a steadier altitude, its fuel would have lasted longer, letting it fly farther south across the Indian Ocean before its tanks ran dry. So the dismissal of the radar altitude data prompted a change in the focus of the search.

Data from the electronic handshakes led investigators to conclude that the aircraft came down in the ocean west of Australia along what is called the seventh arc, the area of the final handshake with the plane. "Everyone agrees that is where the aircraft ran out of fuel," Dolan said.

The Australian government started by searching near the northeast end of the seventh arc, partly because that location was consistent with an aircraft that was limping slowly through the sky because it was damaged, or one that had burned a great deal of fuel in altitude changes. Undersea sounds that were initially thought to be from the plane's locator beacons also pointed to that area, though investigators later decided they were false clues.

Now the search will move hundreds of miles southwest along the arc, consistent with an aircraft flying steadily at a high cruising speed, officials said. Private telecommunications analysts who reviewed the handshakes also concluded that the more likely location of the plane was farther to the southwest.

The specifics are still being finalized, but the new search zone is likely to be a band roughly 400 miles long and about 60 miles wide, straddling the arc.

The width of the band is based on a crucial assumption: that when it ran out of fuel, the plane was being flown by its autopilot, which was unable to control the plane when the engines stopped. In that case, the plane would have stalled and fallen quickly into the ocean. If a skilled pilot was conscious and still at the controls, however, the plane could have glided more than 100 miles before it hit the water.

New York Times