Underwater pings 'most promising lead' in MH370 search

Underwater signals consistent with aircraft black boxes have been detected by an Australian ship, and regarded as the "most promising lead" so far in the month-old hunt for Malaysia Airlines flight MH370.  [Special coverage]

Australian navy ship Ocean Shield twice detected underwater signals consistent with aircraft black boxes, said Angus Houston Monday. Houston heads the Joint Agency Coordination Center (JACC), which is overseeing the international search mission for the missing flight.

According to Houston, one signal lasted for two hours and 20 minutes, the second for 13 minutes.

Houston said the acoustics, emanating from deep in the Indian Ocean, showed that the multinational search by ships and planes seemed to be "very close to where we need to be."

The apparent breakthrough comes as the clock ticks past the 30-day lifespan of the emergency beacon battery fitted to the black boxes of the Boeing 777 plane, which vanished on March 8 with 239 people en route from Kuala Lumpur to Beijing. About two-thirds of the passengers are Chinese.

Four Chinese ships and a British ship on Monday continued the hunt in a second search area in waters where a Chinese vessel also picked up "ping" signals at the weekend.

Chinese patrol ship Haixun 01 reported receiving a pulse signal with a frequency of 37.5 kHz, consistent with the signal emitted by flight recorders, on Friday and again on Saturday.

Houston said the Chinese and Australian discoveries of pings were consistent with work done on analyzing radar and satellite data.

Malaysia's acting transport minister Hishammuddin Hussein on Monday told a press conference in Kuala Lumpur, "We are cautiously hopeful that there could a positive development in the next few days, if not hours."

The investigation can only enter the next phase after the signals were confirmed to be related to the jet, experts said.

"If confirmed, the next step will be locating the black boxes. Since the signals sent from the 4,000- to 5,000-meter-deep water will be distorted or become weaker, the search ships will have to move back and forth to narrow the search area step by step, until they can locate the position accurately," Yu Zhirong, a research fellow with China Maritime Development and Research Center, told the Global Times.

If the black boxes run out of battery before the search ships get a location, authorities can still deploy submersible devices and unmanned undersea vehicles to search for plane debris and try to find black boxes, Yu noted.

"It's a very time-consuming process and there might be safety concerns in searching the deep sea in that area," Li Jie, a naval expert, told the Global Times.

Li warned on Monday that due to the complex seafloor geomorphology, without a thorough seafloor map, search devices might hit undersea mountains and cause casualties if the submersibles are manned.

If the pings are confirmed not to be from MH370, the search is back to square one, raising the daunting specter of an open-ended surface search for floating debris or painstaking seafloor mapping.

But Air France showed that success is still possible. The black boxes of crashed Air France flight 447 in 2009 were not located before their signals expired, necessitating a two-year search using submersible drones and other means to locate debris in the Atlantic Ocean. AF447 was en route from Rio de Janeiro to Paris on June 1, 2009 with 228 people on board when it crashed into the Atlantic.

China's Science and Technology Daily on Saturday quoted Liu Feng, director of China National Deep Sea Center, as saying that the country's manned deep-sea submersible, the Jiaolong, has been prepared to assist the search and rescue efforts in the Indian Ocean.

The Jiaolong is able to reach a depth of nearly 7,000 meters below sea level.

The hunt was adjusted to the southern end of the search zone Sunday after corrected satellite data showed it was more likely the plane entered the water there. The location is thousands of kilometers south of the flight's scheduled route to Beijing.

Malaysian inquiries into the aircraft's disappearance have centered on hijacking, sabotage or psychological problems among passengers or crew, but there is no evidence yet to support any of the theories.