Radar Suggests Jet Shifted Path More Than Once

International New York Times | 14 March 2014

A Royal Malaysian Air Force aircraft participated in the search for the missing Malaysia Airlines jet over the Strait of Malacca on Friday. Credit Mohd Rasfan/Agence France-Presse — Getty Images

SEPANG, Malaysia — Malaysia Airlines Flight 370 experienced significant changes in altitude after it lost contact with ground control, and altered its course more than once as if still under the command of a pilot, American officials and others familiar with the investigation said Friday.

Radar signals recorded by the Malaysian military appeared to show that the missing airliner climbed to 45,000 feet, above the approved altitude limit for a Boeing 777-200, soon after it disappeared from civilian radar and turned sharply to the west, according to a preliminary assessment by a person familiar with the data.

The radar track, which the Malaysian government has not released but says it has provided to the United States and China, showed that the plane then descended unevenly to 23,000 feet, below normal cruising levels, as it approached the densely populated island of Penang.

There, officials believe, the plane turned from a southwest-bound course, climbed to a higher altitude and flew northwest over the Strait of Malacca toward the Indian Ocean.

Detecting a Plane

Two kinds of radar are used to keep track of air traffic from the ground.

Primary radar

Sends out radio signals and listens for echoes that bounce back from objects in the sky.

Transponder Secondary radar Sends signals that request information from the plane’s transponder. The plane sends back information including its identification and altitude. The radar repeatedly sweeps the sky and interrogates the transponder. Other planes in flight can also receive the transponder signals.

THE NEW YORK TIMES

Investigators have also examined data transmitted from the plane’s Rolls-Royce engines that showed it descended 40,000 feet in the span of a minute, according to a senior American official briefed on the investigation. But investigators do not believe the readings are accurate because the aircraft would most likely have taken longer to fall such a distance.

“A lot of stock cannot be put in the altitude data” sent from the engines, one official said. “A lot of this doesn’t make sense.”

The data, while incomplete and difficult to interpret, could still provide critical new clues as investigators try to determine what happened on Flight 370, which disappeared early last Saturday carrying 239 people from Kuala Lumpur to Beijing.

Malaysian and international investigators have said in recent days that the plane may have departed from its northerly route toward Beijing and headed west across the Malaysian peninsula just after the aircraft disappeared from civilian radar, its pilots stopped communicating with ground controllers and its transponders stopped transmitting data about its speed and location. The plane is also now thought to have continued flying for more than four hours after diverting its course, based on automated pings sent by onboard systems to satellites.

But the Malaysian military radar data, which local authorities have declined to provide to the public, added significant information about the flight immediately after ground controllers lost contact with it. The combination of altitude changes and at least two significant course corrections could have a variety of explanations, including that a pilot or a hijacker diverted the plane, or that it flew unevenly without a pilot after the crew became disabled.

The erratic movements of the aircraft after it diverted course and flew over Malaysia also raise questions about why the military did not respond to the flight emergency. Malaysian officials have acknowledged that military radar may have detected the plane, but have said they took no action because it did not appear hostile.

Andaman

Islands

Cambodia

Gulf of

Thailand

Myanmar

Andaman Sea

Thailand

Vietnam

Plane last

recorded flying

at 29,500 feet,

heading northwest.

Plane turns

and climbs

to a higher

altitude.

Plane

descends

unevenly to

23,000 feet.

Plane climbs

to 45,000 feet,

heading in this

direction.

Nicobar

Islands

Plane disappears

from civilian radar.

SearcH

AREA

200 miles

Penang

Indonesia

Strait of

Malacca

South

China

Sea

Malaysia

Indian Ocean

Kuala Lumpur

International Airport

The New York Times

Sources: Malaysia’s Department of Civil Aviation (search areas); flightradar24.com (dotted flight path); Malaysia Airlines

A week after the jet’s disappearance, the Malaysian authorities have shared few details with American investigators, frustrating senior officials in Washington. “They’re keeping us at a distance,” one of the officials said.

But investigators in Malaysia and the United States recently began receiving additional data about the plane and anticipate more over the weekend, according to a senior American official. “It’s gotten better and better every day,” the official said, referring to information from the plane’s manufacturer, satellites and military radar. “It should provide more clarity to the flight path. It’s not a given, but it’s a hope.”

Because the plane stopped transmitting its position about 40 minutes after takeoff, military radar recorded only an unidentified blip moving through Malaysian airspace. Certain weather conditions, and even flocks of birds, can occasionally cause radar blips that may be mistaken for aircraft. The Malaysian authorities said they were still studying the signals to determine whether they came from Flight 370.

But the person who examined the data said it left little doubt that the airliner flew near or through the southern tip of Thailand, then back across Peninsular Malaysia, near the city of Penang, and out over the sea again. That is in part because the data is based on signals recorded by two radar stations, at the Royal Malaysian Air Force’s Butterworth base on the peninsula’s west coast, near Penang, and at Kota Bharu, on the northeast coast. Two radars tracking a contact can significantly increase the reliability of the readings.

Still, Ravi Madavaram, an aerospace engineer at the consulting firm Frost & Sullivan, based in Kuala Lumpur, said the accuracy of ground-based radars in determining a plane’s altitude diminishes the farther away the plane is. When Flight 370 lost contact with ground controllers, it was more than 100 miles from Kota Bharu and 200 miles from Butterworth, distances that he said could degrade accuracy. But the altitudes measured as the plane crossed the peninsula would be more reliable, he said.

A senior aircraft industry executive in the United States said the account of Flight 370’s movements that was emerging from the Malaysian military radar information matched what their officials were told. “Everything we have heard is consistent with the plane flying under the control of someone with at least some flying experience,” said the industry executive, who asked not to be identified because of the tense nature of the conversation underway with the Malaysian authorities.

The search and rescue operation for the Malaysian jet continued over the Strait of Malacca on Friday. Credit Junaidi Hanafiah/Reuters

Military radar last recorded the aircraft flying at an altitude of 29,500 feet, about 200 miles northwest of Penang and headed toward India’s Andaman Islands. The normal cruising altitude of a long-range commercial jetliner is between 30,000 and 40,000 feet.

Cengiz Turkoglu, a senior lecturer in aeronautical engineering at City University London who specializes in aviation safety, said a deliberate act in the cockpit could cause a radical change in altitude. “It is extremely difficult for an aircraft to physically, however heavy it might be, to free fall,” he said.

An Asia-based pilot of a Boeing 777-200, who asked not to be identified because he was not authorized to speak to reporters, said an ascent above the plane’s service limit of 43,100 feet, along with a depressurized cabin, could have rendered the passengers and crew unconscious, and could be a deliberate maneuver by a pilot or a hijacker.

Other experts said that altitude changes would be expected if the pilots became disabled after the plane’s autopilot was disengaged. Changes in the weight distribution on the plane as fuel burned off would make the plane descend and climb repeatedly, though changes in course would be harder to explain.

American officials were concerned in the first few days after the plane disappeared that terrorists had brought it down. But as investigators have examined the flight manifest and looked into the two Iranian men who were on the plane traveling with stolen passports, they have become convinced that there is no clear connection to terrorism.

The Federal Bureau of Investigation interviewed family members of the Iranian men and used computer programs to determine whether they had ties to terrorists. Those efforts showed no such connections, leading the investigators to believe the men were smugglers.

The investigators considered but dismissed the possibility that hijackers landed the plane somewhere for later use in a terrorist attack, according to a senior American official briefed on the investigation.

The data, the official said, “leads them to believe that it either ran out of fuel or crashed right before it ran out of fuel.”

It would take a long runway to land a plane of that size, the official said. Although the radius that the plane could have flown extends into South Asia, the official added, “the idea it could cross into Indian airspace and not get picked up made no sense.”