Flight 370: Searchers race to try to trace sounds detected in ocean

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KUALA LUMPUR, Malaysia (CNN) — Search teams are racing to figure out if a number of underwater sounds detected in the southern Indian Ocean came from a flight recorder on Malaysia Airlines Flight 370.

Time is against them, as the batteries powering the missing plane’s devices that send out pings are expected to expire in the coming days.

The desperate efforts to trace the signals come as new details emerged about the missing plane’s likely path on the night it vanished.

A senior Malaysian government source told CNN that Flight 370 flew around Indonesian airspace after it dropped off Malaysian military radar. The plane may have been intentionally taken along a route designed to avoid radar detection, the source said.

In the search for the plane in the Indian Ocean, a Chinese patrol ship Haixun 01 picked up two signals, one on Friday and another on Saturday, that were only 2 kilometers (1.25 miles) apart, authorities said.

“This is an important and encouraging lead, but one that I urge you to continue to treat carefully,” Angus Houston, the head of the Australian agency coordinating search operations, said Sunday.

The electronic pulses were consistent with those emitted by the pingers on an aircraft’s flight data and voice recorders, he said, but haven’t been verified as coming from Flight 370.

Sounds also travel long distances underwater, he said, making it difficult to ascertain their sources. If detectors were near a pinger, they would pick up the signal for a more sustained period.

Houston also said that search authorities were informed Sunday that Ocean Shield, an Australian naval vessel equipped with sophisticated listening equipment, has detected “an acoustic noise” in another area of the ocean.

The signals are the latest leads in a huge, multinational hunt for Flight 370, which disappeared almost a month ago over Southeast Asia with 239 people on board. Investigators have so far been unable to say why the plane flew far off course or where exactly it ended up.

‘Most promising lead’

HMS Echo, a British navy ship equipped with advanced detection gear, is on its way to the area where the Chinese ship picked up the signals, Houston said. It is likely to arrive in the early hours of Monday morning. Australian planes are also headed to the area.

Ocean Shield, which has a high-tech pinger locator borrowed from the U.S. Navy, will continue to pursue the sound it heard. If that lead turns cold, it will move to the other detection area, a journey that will take at least a day, officials said.

“At the moment, the most promising lead appears to be the one associated with Haixun 01,” he said at a news conference in Perth, the Western Australian city serving as a hub for search operations.

The pulses registered by the Chinese ship are of particular interest because they came in an area that fits with the latest calculation by experts of roughly where the plane is likely to have entered the water, Houston said.

The area of detection is roughly 1,000 miles (1,600 kilometers) west-northwest of Perth, according to coordinates reported by Chinese state media. The water in the area is about 4,500 meters (14,750 feet) deep, authorities said.

Caution urged

Several analysts on CNN said the information from search officials gave cause for optimism.

“We’ve got to be a little careful about groupthink here, but right now the evidence seems to point towards the Chinese vessel’s location,” said Alan Diehl, a former accident investigator for the U.S. Air Force.

What’s more, a number of white objects were spotted floating on the surface of the water about 90 kilometers (56 miles) from where the sounds were detected, authorities said.

But Houston warned that the latest discoveries could turn out to have no connection to the missing plane.

“In the days, weeks and possibly months ahead, there may be leads such as the one I’m reporting to you this morning on a regular basis,” Houston said.

“I assure that we will follow up and exhaust every credible lead that we receive,” he said.

The Chinese vessel detected the second signal for a total of 90 seconds on Saturday, according to authorities.

“It’s not a continuous transmission,” Houston said. “If you get close to the device, we should be receiving it for a longer period of time.”

Plane said to have flown around Indonesia

Authorities say Flight 370 ended up flying south into the Indian Ocean after it dropped off military radar off the west coast of Peninsular Malaysia on March 8. The conclusion is based on an expert analysis of satellite, radar and other available data.

More detail has been added to the flight path calculated by investigators, a senior Malaysian government source told CNN on Sunday.

After reviewing radar track data from neighboring countries, officials have concluded that the passenger jet curved north of Indonesia before turning south toward the southern Indian Ocean. Its path took it around Indonesian airspace.

The plane did not fly over Indonesia or its airspace, the source said.

Malaysian government officials have said previously that the plane appeared to have been deliberately diverted from its original course, which would have taken it north to Beijing.

Investigators haven’t yet said who they think might have flown the plane off course or why. They also haven’t so far ruled out mechanical problems as a cause of the plane’s diversion.

Time running out

So far, no physical evidence of the plane’s eventual whereabouts has been found, leaving many relatives of those on board trapped in uncertainty.

Weeks of searching, initially in the seas around Malaysia and Vietnam, where the plane lost contact with air traffic control, and then in the remote southern Indian Ocean have turned up no traces.

A series of objects spotted in the ocean by satellites and flight crews have turned out to be bits of fishing gear or other things unrelated to Flight 370.

At the end of last week, the search expanded under the waves, as well. The batteries for the missing plane’s pingers are expected to last around 30 days — a deadline that falls on Monday.

“We’re running out of time in terms of the battery life,” Houston said, noting that sometimes the batteries last for a further eight to ten days.

As many as 10 military planes, two civil aircraft and 13 ships have been tasked to help in Sunday’s search for the airline. The Australian Maritime Safety Authority (AMSA) plans to search three separate areas Sunday about 2,000 kilometers (about 1,240 miles) northwest of Perth. That area totals about 216,000 square kilometers (83,000 square miles).

CNN’s Jethro Mullen reported and wrote from Hong Kong, and journalist Ivy Sam reported from Kuala Lumpur. Ralph Ellis and Ben Brumfield contributed to this report.