U.S. Navy Says Too Soon to Rule Out MH370 as Source of Pings

May 28, 2014 10:39 pm ET

(Updates with comment from academic in fifth paragraph)

May 29 (Bloomberg) -- The U.S. Navy said it’s too soon to rule out the missing Malaysian passenger jet’s black box as the source of acoustic signals detected in the Indian Ocean.

Search teams are still analyzing the pings, Chris Johnson, a Navy spokesman, said by e-mail today after another U.S. naval official told CNN that investigators believe the sounds didn’t come from the plane’s onboard data or voice recorders.

Comments by Michael Dean, the Navy’s deputy director of ocean engineering, to CNN were “speculative and premature,” Johnson said by e-mail. “As such, we would defer to the Australians, as the lead in the search effort, to make additional information known at the appropriate time.”

The deep-sea search for the Boeing Co. 777-200 was called off for about three months yesterday so that investigators can assemble a more accurate map of the ocean floor in the region about 1,670 kilometers (1,000 miles) northwest of the Australian city of Perth. No trace of the aircraft has been found in searches from Thailand to the Southern Ocean since the aircraft disappeared March 8 with 239 people on board.

“They’re looking for a fairly large object so you’d have thought they would have picked it up by now,” Peter Marosszeky, a lecturer in aviation at the University of New South Wales in Sydney, said by phone. “I am a little bit skeptical as to whether the aircraft is where they think it might be.”

No Trace

Australia’s naval ship ADV Ocean Shield picked up four separate signals “consistent with the locator on a black box,” Angus Houston, head of the Joint Agency Coordination Centre that’s leading the search for the plane, said in an April 9 media conference.

The sounds on April 5 and April 8 were “a very stable, distinct, and clear signal” at a frequency of 33.331 kilohertz, pulsing at a 1.106 second interval, Houston had said.

“It’s nothing natural,” he said at the time. “It comes from a man-made device.”

The Joint Agency didn’t immediately reply to an e-mail and phone message seeking comment.

Since then, a detailed sonar search with a deep-sea robot submarine has picked up no trace of wreckage from the aircraft.

The signals may have been caused by the search vessel itself or the Towed Pinger Locator, an underwater microphone designed to pick up sonar signals from black box emergency beacons, CNN cited the U.S. Navy’s Dean as saying.

“I’d have to say at this point based on all of the imagery data that we’ve collected and looked at if that black box were nearby we would have picked it up,” he told CNN. “We may very well have been in the wrong place.”

Indian Ocean

MH370’s disappearance 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, then doubled back and flew over Peninsular Malaysia and into the remote waters of the Indian Ocean, according to analysis of satellite signals.

Data exchanges with an Inmarsat Plc orbiter, including a last burst when fuel exhaustion seems to have interrupted the electrical supply, remain the only clues to where the Malaysian Airline System Bhd. plane went down.

On May 27, Malaysia’s department of civil aviation released 43 pages of data logs showing more than nine hours of electronic communications between the 777 and the Inmarsat satellite.

The log includes seven digital “handshakes” with the plane that revealed its distance and direction of flight from the orbiter, and constitutes the entirety of information that Inmarsat has from the aircraft, the U.K. company said.

Ocean Acoustics

“The complexities surrounding the search cannot be understated,” Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, said in a May 26 statement on the agency’s website. “It involves vast areas of the Indian Ocean with only limited known data and aircraft flight information.”

Investigators have scanned 4.6 million square kilometers of ocean, 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 sounds picked up by the Ocean Shield 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.

“There can be acoustics in the ocean that can sound similar to those pings,” he said.

The sound could even have come from an emergency beacon on a life raft on board an oceangoing yacht, Marosszeky said. It’s still likely the aircraft will eventually be located, he said.

“It’s a pretty straightforward case of trying to find a needle in a very big haystack,” he said. “They will find it.”