(WSJ) The Australian navy picked up extended signals from deep underwater that may have come from Malaysia Airlines Flight 370's two "black box" flight recorders, in what authorities said was the best lead yet in a monthlong search.
The naval ship Ocean Shield—fitted with U.S. Navy black-box detector equipment able to pick up signals far beneath the ocean surface—has been searching an area of the southern Indian Ocean off the coast of Western Australia that investigators believe is the most likely spot where the plane may have run out of fuel, more than 1,000 miles from the nearest airport, after disappearing from civilian radar on March 8.The first of the signals was held for more than two hours, retired Air Chief Marshal Angus Houston, who is leading the multinational search, said Monday. On a return trip along the same path early on Sunday morning, two distinct "pinger" signals were detected and held for about 13 minutes.
"Significantly, this would be consistent with transmission from both the flight data recorder and the cockpit voice recorder," Air Chief Marshal Houston said. "Clearly this is a most promising lead and probably in the search so far. The audible signal sounds to me just like an emergency locator beacon," he added.
Searchers still need to fix on a precise location before sending an underwater vehicle to investigate the finding, in an area of ocean some 4,500 meters (14,764 feet) deep, he said. Those depths are at the absolute limit of the undersea vehicle aboard Ocean Shield, after which crews would have to turn to other submersibles or dropping cameras to the ocean floor.
The possible breakthrough comes at a critical time in the search. Locator beacons on the two flight recorders aboard the plane have an estimated battery life of about 30 days before they stop emitting signals. Monday marks the 30th day since the plane vanished on a flight from Kuala Lumpur to Beijing with 239 people on board. The devices, if found, could provide vital clues to what occurred.
In a sign of the significance authorities have apportioned to the latest development, a usually carefully choreographed media conference in Perth ventured for the first time Monday into the potential recovery of aircraft wreckage. If a location can't be fixed based on signals, the navy will decide whether it should go ahead and deploy the underwater vehicle onboard Ocean Shield to scan for wreckage on the seafloor, Air Chief Marshal Houston said. Ocean Shield is carrying an underwater unmanned vehicle—known as a Bluefin 21—but it has an operating limit of around 15,000 feet. Other underwater vehicles may have to be brought in that can handle depths exceeding that level, he said.
Authorities were careful Monday to inject some caution into the latest development, however, in a search that has been plagued by false leads.
"In deep water, funny things happen with acoustic signals," Air Chief Marshal Houston said. "I would not be prepared to confirm that this is the spot where the aircraft is on the present evidence," he said. "Without wreckage, we can't say it's definitely here. We have to go down and look."
Air-safety experts have said other maritime locating devices also use similar frequencies to flight recorders. Following a signal that search teams detected on April 3 but later discounted, the Australian agency leading the search operation warned that biological sources, such as whales, and shipping could lead to false alerts.
Commander William Marks, a spokesman for the U.S. Navy's Seventh Fleet, said the Ocean Shield picked up returns "with a slight variation in frequency." He said that could be explained because the pingers for the two recorders aren't precisely the same age and their acoustic signals could vary slightly as a result.
The Ocean Shield was searching at the northern end of an arc determined as the most likely flight path for the missing Boeing 777-200 jetliner, based on updated satellite and aircraft performance data, when it made the discovery. On Friday and Saturday a Chinese vessel, Haixun 01, reported detecting several "acoustic pings" about 1.2 miles apart—about 300 nautical miles from the Australian naval ship on the edge of the southernmost of three designated search zones.
The Chinese listening device was designed to identify sounds at depths of less than 1,000 feet, according to one person briefed on the Flight 370 probe, while the ocean bottom in parts of the search area exceeds 13,000 feet.
Still, Air Chief Marshal Houston said Monday the Australian finding doesn't rule out the earlier Chinese discovery. If the plane flew at a slightly higher speed than would be normal, it would likely have hit the water near the Chinese vessel. If it flew somewhat slower and burned less fuel, it likely would have crashed into the ocean nearer to the Ocean Shield location. U.K. navy ship HMS Echo was on its way to assist the Chinese vessel in its search on Monday.
The former Australian defense chief warned that even if searchers can recover the signal again and accurately pinpoint the wreckage, they are in for a long-haul recovery effort with the Southern Hemisphere winter fast approaching.
"We're talking about a long operation here that will be measured in months," Air Chief Marshal Houston said. "It will take several days to actually cover what would appear to be a fairly small area. Things happen very slowly at the depths we are dealing with," he said. "Some of the water out there exceeds 5,000 meters, which is going to be very challenging."
Source: Wall Street Journal by Robb M. Stewart and Racel Pannett
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