Plane hunt fails to find new pings

April 12 -- Authorities hunting for the black boxes on the missing Malaysian Air jet failed to detect their signals during the latest search efforts, increasing the likelihood that the devices' battery power has run out.

"There have been no confirmed acoustic detections over the past 24 hours," Australia's Joint Agency Coordination Centre said today. The difficulty of locating the black boxes shouldn't be underestimated and the search was likely to continue "for a long time to come," Prime Minister Tony Abbott told reporters in Beijing.

Four signals detected between April 5 and 8 with the towed pinger locator pulled by Australia vessel Ocean Shield helped tighten the hunt for the Malaysian Airline System Bhd. plane. Hopes of a breakthrough dissipated yesterday when JACC said that an initial assessment of a fifth potential transmission, picked up by a sensor-equipped buoy dropped by a search plane, wasn't related to an aircraft black box.

"It's possible the battery power is either running down that the signal becomes weaker and so you have to get much closer to be able to hear," Chris Yates, a London-based aviation consultant at Yates Consulting, said in a phone interview today. "Or it means the black box is already dead."

The center of today's search areas was 2,331 kilometers (1,448 miles) northwest of Perth, with as many as 10 aircraft and 14 ships taking part, JACC said. Today's visual search spanned an area of 41,393 square kilometers.

'Massive Task'

"We have very considerably narrowed down the search area but trying to locate anything four and a half kilometers beneath the surface of the ocean, about a 1,000 kilometers from land, is a massive, massive task," Abbott said today.

He said yesterday he was confident the position of the flight-data and cockpit-voice recorders had been narrowed down to "within some kilometers" in the Indian Ocean.

Zeroing in on the source of acoustic pulses linked to Flight 370's black-box beacons is pivotal and will help determine when investigators will launch a robot submarine to scan the seabed. The Bluefin-21 sub aboard the Ocean Shield moves slowly and relies on sonar to spot wreckage in pitch-black waters thousands of meters deep, limiting the area it brings under surveillance.

The challenge is that the pingers' batteries are already beyond their 30-day projected life at full power, leaving investigators in a race against time to detect more pulses and map the ideal launch zone for the Bluefin-21.

Submarine Launch

"We are now looking at the next phase of this search, which is actually going down underwater," Malaysia's acting transport minister Hishammuddin Hussein told reporters today at Sepang outside Kuala Lumpur. The submarine wouldn't be launched until "we are more sure that the signals are coming from those black boxes."

Authorities are pinning their hopes on recovering the black boxes to learn why the Boeing Co. 777-200ER disappeared March 8 en route to Beijing from Kuala Lumpur. The plane reversed course and flew into some of the world's most-remote ocean waters with 239 passengers and crew members.

The Ocean Shield detected two signals on April 5 and two more on April 8 that authorities have linked to the beacons on Flight 370's black-box recorders, giving authorities a boost in a search that has failed to produce any physical evidence.

Co-pilot Fariq Abdul Hamid attempted to make a phone call from his mobile phone shortly before the aircraft disappeared from radar some 320 kilometers northwest of Penang, the New Straits Times reported today, citing unidentified people. His call ended abruptly after contact was established with a telecommunications sub-station in Penang, the Malaysian paper said, adding that it didn't know who the pilot tried to call.

The newspaper quoted another unnamed person as saying the connection to the substation could mean the phone was turned back on, without a call being made.

Malaysia's police chief Khalid Abu Bakar declined to comment on the report in a phone text message to Bloomberg News.

--With assistance from John Walcott and Alan Levin in Washington, Shamim Adam and Kyunghee Park in Singapore, Laura Hurst in London, Zachary Tracer in New York, Michael Heath, Edward Johnson, David Fickling, Narayanan Somasundaram and Michael Sin in Sydney, Andrea Rothman in Toulouse, Thomas Black in Monterrey , Helen Yuan in Shanghai and Liau Y-Sing and Manirajan Ramasamy in Kuala Lumpur.