A submarine scouring the floor of the Indian Ocean for the missing Malaysian jet had to abort its maiden voyage after descending too deep, providing investigators with less than half the data the equipment was meant to capture.

 

The Bluefin-21 vessel was forced back to the surface by a built-in safety feature after dropping below its limit of 4,500 meters (14,800 feet), Australia’s Joint Agency Coordination Centre said in an e-mailed statement. No objects of interest were found in the six hours of data that was captured, said Daniel Marciniak, a spokesman for the U.S. Seventh Fleet, which operates the Bluefin-21, in an e-mailed statement.

 

“That’s not good news,” Robin Beaman, a marine geologist at James Cook University in Cairns, Australia, said by phone. “The critical thing is it needs to be down close to the seafloor.”

 

The submarine will continue its hunt later today when weather conditions permit, JACC said. As many as 11 aircraft and 11 ships will comb about 62,063 square kilometers (23,943 square miles) of ocean today for signs of debris from the jet. Investigators are relying on the submersible after stopping the use of a towed pinger locator to find the plane’s black boxes.

 

Bluefin-21

 

The use of the submarine is the latest phase of an international search for Flight 370, which disappeared March 8 with 239 people on board. At 39 days, it’s now the longest search for a missing passenger jet in modern aviation history. No audio signals have been detected since April 8, suggesting the aircraft’s black boxes have run out of power.

 

The Bluefin-21 reached a depth of 4,500 meters in a charted area of 4,400 meters. This “unexpected condition” resulted in an automatic mission abort, the JACC said in a separate e-mailed statement.

 

“The vehicle is in good material and working condition” and wasn’t damaged in the dive, in which it travelled about 30 meters above the sea floor, Marciniak said.

 

The Bluefin-21, equipped with side-scan sonar, is supposed to be deployed for 24 hours at a time. It is intended to spend two hours descending, 16 hours on the ocean bottom, two hours returning to the surface, and four hours having its data downloaded, Angus Houston, who heads the JACC, told reporters yesterday. It was to search an area of about 40 square kilometers to produce a high-resolution, three-dimensional sonar map of the seabed, he said.

 

Extreme Pressure

 

Side-scan sonar need to operate close to the sea floor as it operates by casting acoustic shadows to the sides of the sensors, Beaman said. That means it works better if the sensor is low down, like the evening sun, rather than high up and casting smaller shadows like those around midday.

 

“The Bluefin is a very capable machine, but at 4.5 kilometers down, things implode,” Beaman said. “They run the risk of losing it entirely,” he said.

 

The submersible will stop its mission if the bottom drops away from it in a way that would cause it to exceed its rated depth, said David Kelly, president of Bluefin Robotics Corp., the device’s manufacturer, in an interview with Bloomberg Television. At depths of 4,500 meters, it’s “pitch black,” the water temperature is slightly above freezing and objects will be subject to high pressure, he said.

 

“It would be equivalent to having a Cadillac Escalade pushing down on your thumbnail,” Kelly said.

 

Ocean Shield

 

Bluefin Robotics hadn’t received any call for an alternative vehicle at this stage, he said.

 

The underwater sonar search could take up to two months, the U.S. Navy’s Seventh Fleet said in an e-mailed statement yesterday.

 

The black boxes are key to determining why the Malaysian (MAS) Airline System Bhd. plane disappeared en route to Beijing from Kuala Lumpur, reversing course and flying into some of the world’s most remote ocean waters. The pingers’ batteries are now a week beyond their 30-day projected life at full power.

 

Australia’s Ocean Shield ship, using the towed pinger locator, detected two signals on April 5 and two more on April 8, which authorities have linked to the beacons on the Boeing Co. 777-200ER’s black-box recorders. That raised optimism in the search. Hopes faded on April 11 when the JACC said an initial assessment of a fifth potential transmission wasn’t related to an aircraft black box.

 

Scouring the ocean surface for debris with planes and ships will be called off in two to three days as the chance of any floating material being recovered has “greatly diminished,” Houston said at a press conference in Perth yesterday.

 

Deliberately Steered

 

An oil slick found in the same area was of “super fine consistency,” Marciniak said, adding it’s being transferred to Perth.

 

Flight 370’s disappearance has baffled authorities because contact was lost less than an hour into a routine trip to Beijing from Kuala Lumpur. The widebody plane vanished from civilian radars while headed north over the Gulf of Thailand, then doubled back and flew over Peninsular Malaysia and on into some of the world’s most remote waters.

 

While the motive behind that heading remains unknown, MH370 was deliberately steered south on a path ending in the Indian Ocean, Malaysian Prime Minister Najib Razak has said. The cause of the disappearance might never be known, Malaysian police chief Khalid Abu Bakar said April 3, according to a recording provided by a member of his communication staff.

 

Police have interviewed more than 170 people, including relatives and acquaintances of the 227 passengers and 12 crew members of Flight 370, Khalid said. A home-computer flight simulator belonging to the jet’s captain Zaharie Ahmad Shah was also being probed.

 

Police are still investigating the pilot and the co-pilot, Malaysia’s acting Transport Minister Hishammuddin Hussein told reporters in Kuala Lumpur today.

 

To contact the reporters on this story: David Fickling in Sydney at [email protected]; Kyunghee Park in Singapore at [email protected]

 

To contact the editors responsible for this story: Anand Krishnamoorthy at [email protected] Edward Johnson