MH370 'ping' search fails

Authorities from Australia, coordinating international efforts to find the missing Malaysian Airlines Boeing 777, said on Thursday that an area of the seafloor once considered the likely crash site can be ruled out of the search.

A special unmanned US Navy deepwater submarine, the Bluefin-21 submersible robot (pictured), finished scouring the seabed without detecting any trace of the wreckage.

"The data collected on yesterday's mission has been analyzed," Australia's Joint Agency Coordination Centre (JACC) said in a statement. "As a result, JACC can advise that no signs of aircraft debris have been found by the Autonomous Underwater Vehicle since it joined the search effort."

The search area in question is a smaller segment of the broader region of the Indian Ocean, where authorities still believe the plane crashed.

The area was identified last month after a series of four acoustic pings, thought to hail from MH370's black box, were heard by a special listening device.

The head of the search operation, Angus Houston, had once described this as the "most promising lead" in the hunt for the missing plane, Australian Prime Minister Tony Abbott also expressed optimism at the time.

"The Australian Transport Safety Bureau has advised that the search in the vicinity of the acoustic detections can now be considered complete and in its professional judgment, the area can now be discounted as the final resting place of MH370," the JACC said.

Search to continue on unmapped sea floor

The ping-inspired search scoured an area of 850 square kilometers (330 square miles), but the MH370 is still believed to have crashed in a much larger area of up to 60,000 square kilometers.

Much of this remote oceanic region is not properly mapped, with the depth of the water often unknown.

A Chinese ship, supported by two Malaysian vessels, is currently mapping the ocean floor on a mission expected to take around three months. A submarine capable of diving even deeper than Bluefin-21 could be required to search for debris under the water itself.

Raw satellite data used in the search was released on Tuesday. The JACC said a commercial operator would continue the search of the sea floor would resume in August.

Malaysian Airlines Flight MH370 mysteriously disappeared on March 8 on a flight from Kuala Lumpur to Beijing. Standard tracking equipment on board the plane was disabled and the Boeing 777 is known to have taken a major detour from its pre-approved flight path; but the reasons for this remain a mystery. A total of 239 people were on board, the majority of them from China.

msh/ipj (AFP, AP, dpa, Reuters)