Malaysia Airlines: Ship Picks Up Signals Consistent With 'Black Box' Pings; Development Is Best Lead Yet in Search for Missing Flight 370, Authorities Say

The Wall Street Journal

By Robb M. Stewart in Melbourne and Rachel Pannett in Sydney

Updated April 7, 2014 1:27 p.m. ET

The Australian navy picked up extended underwater signals in the search zone for Malaysia Airlines Flight 370, in what authorities said Monday was the best lead yet in the hunt for the jet's "black box" flight recorders.

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 for nearly two days. Investigators believe the area is the most likely spot where the plane may have run out of fuel, more than a thousand miles from the nearest airport, after disappearing from civilian radar on March 8.

The first of the signals late at night on Saturday local time 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 Sunday, 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…The audible signal sounds to me just like an emergency-locator beacon."

So far, the multinational team of military aircraft have failed to spot any debris related to Flight 370 on the surface of the ocean in more than two weeks. Instead, investigators have relied on radar, satellite communications and other data to plot where they believe plane likely went down.

That analysis, which has been revised several times, steered the Australian-led search operation to direct the Ocean Shield to an area of ocean about 650 miles from the town of Exmouth on the Western Australian coast.

Once on site, the Ocean Shield swept back and forth across a seven-mile strip of open sea, towing the black box detector equipment some 3,000 meters, or nearly two miles, beneath the surface. The highly sensitive equipment usually needs to come within about 2,000 meters of the black boxes to register their pings, Australian Navy Commodore Peter Leavy said.

Sounds under the surface are affected by temperature, pressure and salinity, which can affect the quality and range of any underwater signals, he said.

Air Chief Marshal Houston said searchers still needed to fix on a precise location before sending an underwater vehicle to investigate the finding, in an area of ocean some 4,500 meters deep. Those depths are at the absolute limit of the undersea vehicle aboard Ocean Shield, which might mean that crews would have to turn to other submersibles or drop cameras to the ocean floor to investigate.

Monday's announcement came 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 marked the 30th day since the plane vanished on a flight from Kuala Lumpur to Beijing with 239 people on board.

But in a hunt that has been fraught with false leads and setbacks, authorities were careful to inject some caution.

"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 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, 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 are not 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, 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" 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 slower speed than would be normal with better fuel conservation, it would likely have hit the water near the Chinese vessel. If it flew somewhat faster and burned more fuel, it likely would have crashed into the ocean nearer to the Ocean Shield location. A 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 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."

—Andy Pasztor and Daniel Stacey contributed to this article.

Source:   http://online.wsj.com