By Narayanan Somasundaram, Michael Sin and Alan Levin
April 10 (Bloomberg) — An Australian search plane picked up a transmission around the area where a ship previously heard pings, a day after investigators expressed optimism they can soon locate the missing Malaysian Air jet in the Indian Ocean.
A Royal Australian Air Force AP-3C Orion aircraft detected the possible signal “in the vicinity” of where defense ship Ocean Shield earlier heard pings, Australia’s Joint Agency Coordination Centre said in an e-mailed statement today. The signal was collected by a sensor-equipped sonobuoy, which floats on ocean surface after they are parachuted out of aircraft.
“The acoustic data will require further analysis overnight, but shows potential of being from a man-made source,” Air Chief Marshal Angus Houston, who heads the JACC, said in the statement.
The latest findings follow previous contacts in the last five days, as investigators seek to narrow the search area enough to deploy a robot submarine that can scan the seabed for possible wreckage. Even after a monthlong operation, salvage crews have failed to retrieve any debris matching the Boeing 777-200, and the search field has shifted thousands of miles as teams trawl the Indian Ocean.
The sonobuoys, equipped with a radio that transmits data back to the aircraft, will deploy a hydrophone 1,000 feet below the surface of the ocean, JACC said in a separate statement.
The pulses heard on April 8 following two April 5 contacts bolstered authorities’ confidence that they are finally zeroing in on debris a month after Flight 370 vanished. Knowing where to start underwater surveillance is pivotal before committing the Ocean Shield’s sonar-equipped submersible.
The two most recent sounds heard by the ship were faint and partially obscured by background noise, according to Phoenix International Holdings Inc., the Largo, Maryland-based contractor operating the U.S. Navy’s towed pinger locator aboard the Ocean Shield. Australia’s JACC said one of the contacts heard by the vessel lasted for 5 minutes and 32 seconds, and the other for 7 minutes.
Fading power reserves for the beacons on the Boeing Co. 777-200ER’s cockpit-voice and flight-data recorders add urgency to the search. The batteries are nearing the end of their life span after the Malaysian Airline System Bhd. plane disappeared en route to Beijing from Kuala Lumpur on March 8. On board were 239 passengers and crew members.
The search area for today was narrowed to 57,923 square kilometers, the JACC said in a statement. Up to 10 military aircraft, four civil aircraft and 13 ships will assist in the operations, about 2,280 kilometers northwest of Perth.
Aircraft and ships reported spotting a large number of objects during yesterday’s search, according to the statement. Only a small number were able to be recovered, it said.
The Ocean Shield carries an unmanned sub, the Bluefin-21, that is ready to launch and start scouring the seafloor with sound waves once the search zone is refined, Houston said. Water depths in the area exceed about 4,500 meters (14,800 feet), far from any natural light from the surface.
By passing back and forth across the area, the search vessel and the towed pinger locator are “narrowing the probability circle of where the debris field is suspected to be,” said John Fish, a principal of Bourne, Massachusetts-based American Underwater Search & Survey Ltd.
Sounds from the pingers don’t travel as far when the signal weakens, so picking up the new contacts suggests that the Ocean Shield is getting closer to the wreckage, said Fish, whose company has helped recover numerous aircraft and their black-box recorders from underwater.
The pingers have a range of about 2 miles (3.2 kilometers), according to the manufacturer, Dukane Seacom, a unit of Hollywood, Florida-based Heico Corp. The black-box maker is Morris Township, New Jersey-based Honeywell International Inc.
Dukane Seacom has analyzed data collected on the pings and concluded that the signals “would be very difficult to be anything else than the acoustic signature of a beacon,” President Anish Patel said in a telephone interview. “Does it have to be the black-box beacon? It could be something else, but the likelihood of it being something else is doubtful.”
Analysis of earlier pings heard by the Ocean Shield determined that a “very stable” signal was detected at 33.331 kilohertz and it consistently pulsed at 1.106-second intervals, JACC’s Houston said. Two signals — one lasting two hours and 20 minutes and the other for 13 minutes — were detected after the deployment of the pinger locator. On the second pass, two pinger signatures were recorded simultaneously, Houston said April 7.
Dukane Seacom’s pingers are supposed to pulse at 37.5 kilohertz. While the units are designed to have a tolerance of plus or minus one kilohertz from the intended frequency, the difference between the intended signal and the pulses picked up at sea in recent days may not be significant, Patel said.
Tests on a beacon recovered from Air France Flight 447, the jet that crashed in the South Atlantic in 2009, found that the unit had shifted frequency after months on the ocean floor, transmitting at 34 kilohertz, Patel said.
According to a map from the Australian Maritime Safety Authority, the four pings heard so far came from a triangular zone with one side almost 30 kilometers long. The distances between the four detections may be explained by the fact that there are two black boxes, each with a pinger, Fish said.
Even after sending the Bluefin-21 into the water to prowl the ocean bottom with sonar, the search may face complications because of a blanket of silt several meters deep on the seabed, Houston said.
Houston said the location of the pings is lining up with other evidence of where the plane may be. The underwater sounds were detected near where analysts estimate a final, partial satellite signal was received from the Malaysian plane, Houston said.
That last pulse to an Inmarsat Plc satellite is where investigators believe the 777’s two engines may have flamed out, Houston said. It’s probably significant in terms of the end of powered flight, he said.
The jet’s disappearance is now the longest in modern airline history, baffling authorities because contact was lost less than an hour into a routine trip as Flight 370 headed north over the Gulf of Thailand. After vanishing from radar, the wide- body craft doubled back, flew over Peninsular Malaysia and on into some of the world’s most remote waters.
While the motive behind that heading remains unknown, Flight 370 was deliberately steered south on a path ending in the Indian Ocean, Malaysian Prime Minister Najib Razak has said.
–With assistance from John Walcott in Washington, Shamim Adam and Kyunghee Park in Singapore, Jason Scott in Perth, Laura Hurst in London, Zachary Tracer in New York, Michael Heath, Edward Johnson and David Fickling in Sydney, Andrea Rothman in Toulouse and Thomas Black in Monterrey .
Copyright 2014 Bloomberg.