David Fickling (c) 2014, Bloomberg News.
SYDNEY — A deep-sea hunt for the missing Malaysian passenger jet has focused on the wrong place for nearly two months, officials said Thursday, after a survey of a remote stretch of the Indian Ocean found no trace of wreckage.
A zone where acoustic pings like those emitted by aircraft black boxes were detected in early April “can now be discounted as the final resting place of MH370,” Australia’s Joint Agency Coordination Centre said in a statement. The undersea survey using robot submarines will resume over a wider 60,000 square kilometer (23,000 square mile) area in August.
The announcement is the latest setback in what is already the longest search mission of the passenger-jet era. Investigators have scoured waters from the South China Sea to the Southern Ocean without finding a fragment of the Boeing 777-200, which disappeared on March 8 with 239 people on board.
“It’s a pretty straightforward case of trying to find a needle in a very big haystack,” Peter Marosszeky, a lecturer in aviation at the University of New South Wales in Sydney, said by phone Thursday. “To locate anything on the sea floor is always very difficult.”
Investigators have scoured a 850-square-kilometer stretch of the ocean floor since April 14 using side-scan sonar, after an underwater microphone picked up four signals like those emitted by aircraft black boxes on April 5 and April 8.
The sonar technology was used to locate the lost Air France 447 aircraft off the coast of Brazil, and can pick out objects less than a meter in size.
“The audible signal sounds to me just like an emergency locator beacon,” the agency’s chief Angus Houston told a media conference April 7 announcing the detection of the first two pings. “We’re very close to where we need to be.”
That survey was called off without success Wednesday, and investigators will now use ship-based sonar to assemble a more accurate map of the seabed before resuming the hunt, the Agency said. The renewed undersea search will be carried out by private contractors and won’t start until the seabed mapping is complete in about three months.
“The search in the vicinity of the acoustic detections can now be considered complete,” the agency said today. “No signs of aircraft debris have been found.”
The Chinese survey ship Zhu Kezhen has begun mapping areas of the seabed identified by Australian authorities in advance of an undersea search slated to begin in August. The Australian Transport Safety Bureau is preparing a bid request for a single contractor to manage the effort.
The disappearance of Malaysian Airline System Flight 370 has baffled authorities because contact was lost less than an hour into a trip to Beijing from Kuala Lumpur. The jet vanished from civil radar while headed north over the Gulf of Thailand.
In the early days of the search, Vietnamese authorities trawled for floating objects spotted in the South China Sea by a Chinese satellite, before data showed the aircraft had tracked back across the Malay peninsula.
Indian authorities scoured parts of the Andaman Sea and the coast of Bengal after a tip-off from Malaysia before data from an Inmarsat orbiter indicated the aircraft had turned south toward a remote part of the southern Indian Ocean. The Australian-led search mission in that area at first focused on a zone close to the turbulent Southern Ocean before fresh analysis of satellite and fuel data indicated the plane probably ditched in tropical waters further to the north.
Data exchanges with the Inmarsat satellite, including a last burst when fuel exhaustion seems to have interrupted the electrical supply, remain the only clues to where the plane went down.
Analysis of the time the signals took to travel to and from the satellite, the degree of distortion in the transmissions, and the fuel load on the jet led investigators to narrow the crash zone down to the ocean off the West Australian coast.
Investigators have scanned 4.6 million square kilometers of ocean surface, with 29 aircraft carrying out 334 flights and 14 ships afloat as part of the operation, Australia’s Deputy Prime Minister Warren Truss said at a May 5 press conference.
In its budget earlier this month, the country’s government set aside A$89.9 million ($83 million) in costs for the hunt over the two years ending June 2015.
It’s possible that the acoustic pings were interference from other ships in the area or sonar equipment, Ken Mathews, a former air accident investigator for New Zealand’s Transport Accident Investigation Commission, said by phone from the Australian city of Cairns today.
“There can be acoustics in the ocean that can sound similar to those pings,” he said.
— With assistance from Jason Scott in Canberra.