MH370 - Ship detects possible black box signals

'This is a most promising lead,' head of the Australian 

agency co-ordinating the search says

The Associated Press Posted: Apr 07, 2014 12:32 AM ET Last Updated: Apr 07, 2014 7:04 AM ET

Commander James Lybrand, right, watches from the bridge with Captain Nick Woods, Master of the ship, left, as they tow a pinger locator behind the Royal Australian Navy ship Ocean Shield in the southern Indian Ocean. Ocean Shield, which is carrying high-tech sound detectors from the U.S. Navy, is investigating a sound it picked up. (Bradley Darvill/Australian Defence Force/The Associated Press)

Underwater sounds detected by a ship searching the southern Indian Ocean for the missing Malaysia Airlines jet are consistent with the pings from aircraft black boxes, an Australian official said Monday, dubbing it "a most promising lead" in the month-long hunt for the vanished plane.

Angus Houston, the head of a joint agency co-ordinating the search, warned that it could take days to confirm whether the signals picked up by the Australian navy ship Ocean Shield are indeed from the black boxes that belonged to Flight MH370, but called the discovery very encouraging.

"Clearly this is a most promising lead, and probably in the search so far, it's probably the best information that we have had," Houston said at a news conference. "We've got a visual indication on a screen and we've also got an audible signal — and the audible signal sounds to me just like an emergency locator beacon.

After a month-long search for answers filled with dead ends, Monday's news brought fresh hope given that the two black boxes, which contain flight data and cockpit voice recordings, are the key to unravelling exactly what happened to Flight MH370 and why.

Malaysian Defence Minister Hishammudin Hussein told reporters that in light of the new information, "We are cautiously hopeful that there will be a positive development in the next few days, if not hours."

There was little time left to locate the devices, which have beacons that emit "pings" so they can be more easily found. The beacons' batteries last only about a month — and Tuesday marks exactly one month since the plane disappeared during a flight from Kuala Lumpur, Malaysia, to Beijing with 239 people on board.

'I would want more confirmation'

The Australian navy's Ocean Shield, which is carrying high-tech sound detectors from the U.S. Navy, picked up two separate signals late Saturday night and early Sunday morning within a remote patch of the Indian Ocean far off the west Australian coast that search crews have been crisscrossing for weeks. The first signal lasted two hours and 20 minutes before it was lost. The ship then turned around and picked up a signal again — this time recording two distinct "pinger returns" that lasted 13 minutes, Houston said.

"Significantly, this would be consistent with transmissions from both the flight data recorder and the cockpit voice recorder," Houston said.

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Still, Houston cautioned that it was too early to say the transmissions were coming from the missing jet.

"I would want more confirmation before we say this is it," he said. "Without wreckage, we can't say it's definitely here. We've got to go down and have a look."

The airliner's black boxes normally emit a frequency of 37.5 kilohertz, and the signals picked up by the Ocean Shield were both 33.3 kilohertz, said U.S. Navy Capt. Mark Matthews. But officials contacted the device's manufacturer and were told the frequency of black boxes can drift near the end of their shelf lives.

The Ocean Shield was slowly canvassing a small area trying to find the signal again, though that could take another day, Matthews said.

"It's like playing hot and cold when you're searching for something and someone's telling you you're getting warmer and warmer and warmer," he said. "When you're right on top of it you get a good return."

If they pick up the signal again, the crew will launch an underwater vehicle to investigate, Matthews said. The Bluefin-21 autonomous sub can create a sonar map of the area to chart where the debris may lie on the sea floor. If it maps out a debris field, the crew will replace the sonar system with a camera unit to photograph any wreckage.