Flight 370 Hunt Pauses as Seabed Map With Sub Seen Among Needs

May 29, 2014 6:56 pm ET

May 30 (Bloomberg) -- Investigators are hitting the reset button in the hunt for the missing Malaysian Air jet.

After finding no evidence in the Indian Ocean search zone scoured by submarine for the past two months, authorities are taking a pause to map the seabed. One possibility: Wreckage may be in part of the area too deep for the Bluefin-21 sub. New equipment will be needed to reach those depths when work resumes later this year, said two people with knowledge of the effort.

The acoustic signals heard off the coast of Australia last month remain under study, said one of the people, who asked not to be identified because the details aren’t public. Even with no debris and the lack of a precise match with the pingers on the plane’s black-box recorders, officials aren’t yet ruling out a link between the sounds and Flight 370, said the person.

“It’s a pretty straightforward case of trying to find a needle in a very big haystack,” Peter Marosszeky, a lecturer in aviation at the University of New South Wales in Sydney, said by phone. “To locate anything on the sea floor is always very difficult.”

The Bluefin-21, named Artemis by its U.S. operators, is able to reach depths of about 4,500 meters (2.8 miles), according to Australia’s Joint Agency Coordination Center. Phoenix International Holdings Inc., the U.S. company performing the search under contract to the Navy, determined that the sub could go deeper, according to an April 17 JACC statement.

The initial submarine search was conducted “within its depth limits,” the JACC said yesterday.

Seabed Map

The deep-sea surveillance was called off for about three months so investigators can draft a more accurate map of the ocean floor in the region about 1,670 kilometers (1,000 miles) northwest of Perth, Australia. That’s the area where an analysis of satellite transmissions suggests Flight 370 splashed down after running out of fuel, according to the JACC.

No trace of the Malaysian Airline System Bhd. aircraft has been found since it disappeared on March 8 with 239 people on board while en route to Beijing from Kuala Lumpur.

The Bluefin-21 had been studying the seabed using side-scan sonar in the vicinity of four acoustic signals heard on April 5 and April 8. Each of the two crash-proof black box recorders on Flight 370 was equipped with a device that emits a once-a-second ping that is outside the range of human hearing.

The first two signals recorded from April 5 were at a frequency of 33.331 kilohertz, which is slightly below the expected frequency of 37.5 kilohertz, according to an April 9 briefing by Angus Houston, who is leading the JACC.

Other Source?

Michael Dean, the U.S. Navy’s deputy director of ocean engineering, said in a May 28 interview with CNN that the lack of wreckage suggests the original pings probably came from some other source, not the wide-body 777.

“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.”

Dean’s comments were “speculative and premature,” Christopher Johns, a U.S. Navy spokesman, said in an e-mail. It’s up to the Australians, who are acting as the lead of the search, to release information on the pingers, Johns said.

Yesterday’s announcement from the Australian JACC didn’t discuss the analysis of the pingers.

Baffling Disappearance

Flight 370’s disappearance has baffled authorities because contact was lost less than an hour into a trip to Beijing. 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 the analysis of satellite signals.

Data exchanges with an Inmarsat Plc satellite, including a last burst when fuel exhaustion seems to have interrupted the electrical supply, remain the chief clues to where the 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 -- all the information that Inmarsat has, the U.K. company said.

“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 surface, 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.