14 April 2014
Six Days Since Last Pings Detected; Next Step Likely to Involve Underwater Vehicle
A spotter looks out of a window in search of debris from the missing Malaysia Airlines Flight 370 on Sunday. Associated Press
SYDNEY—The multinational hunt for Malaysia Airlines Flight 370 was facing up to the possibility that the plane’s black-box flight recorders may have lost battery power, after another day of fruitless searching for underwater signals using ships and aircraft on Sunday.
Australian authorities said Monday that it was now six days since the naval vessel Ocean Shield last detected a series of pings consistent with aircraft black boxes in an area of the southern Indian Ocean. Still, they planned to keep trying to detect more signals using underwater listening equipment for at least another day, delaying a decision on when they might deploy a remote-controlled vehicle to roam the seabed for plane debris.
In a statement, the Joint Agency Coordination Centre said the Ocean Shield would seek to make “more focused sweeps” with a U.S. Navy device that can detect pings from the black boxes’ locator beacons thousands of meters below the ocean’s surface. Australian military aircraft would also continue to log information from scores of underwater listening devices—known as “sonobuoys”—dropped into the ocean last week, with microphones extending some 1,000 feet underwater. The center of the search zone is some 2,200 kilometers (1,367 miles) northwest of the Western Australian state capital of Perth.
The Australian-led search faces a tough decision on how long to wait before deploying the unmanned Bluefin-21 submersible, which authorities hope will provide visual confirmation of Flight 370 on the seabed. Locating the black boxes would be a significant advance as investigators seek to explain what caused the plane to deviate from its flight path and vanish from radar screens en route to Beijing from Kuala Lumpur on March 8.
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That search will be challenging in the absence of new pings. Military officials leading the search say they are facing a search zone some 1,300 square kilometers (about 500 square miles) in size, a vast area for an underwater vehicle that moves at walking pace and would be capable only of covering about 30 square kilometers a day.
A handout image released by the Australian Maritime Safety Authority on Sunday shows the current planned search area in the Indian Ocean. European Pressphoto Agency
The Bluefin-21 can be programmed to conduct a specific search mission of around 20 hours, using side-scan sonar to scroll back and forth looking for unique features on the ocean floor. Once hauled back on board, its data are downloaded and analyzed.
If operators on the Ocean Shield discover an anomaly on the seabed, the Bluefin-21 would have its sonar scanning equipment stripped off and replaced with a high-grade underwater camera. The submersible can accommodate only one of the two systems at a time.
Further complicating the search is a lack of knowledge about what conditions the vehicle will encounter on the seabed. Authorities expect to encounter a blanket of silt, which may be covering part or all of the plane debris, and the possibility of strong underwater currents. Still, they are relying heavily on calculated guesswork. Expectations of silt are based on a seabed survey several decades ago of an area more than 100 kilometers away from the current search zone.
Meanwhile, Malaysian authorities are stepping up preparations for the next phase of an operation already into its 38th day. Authorities are consulting with international legal experts to consider which country should get custody of the black boxes if they are retrieved, Defense Minister Hishammuddin Hussein said Sunday.
Precedent in airline crashes would give the country overseeing the search—in this case, Malaysia—authority to determine how the black boxes are recovered and analyzed. Kuala Lumpur so far has delegated large parts of the search and investigation to countries and agencies with better technical resources, and it is expected to designate foreign experts to download data from the devices.