Investigators searching for the missing Malaysian jet have concluded an area where acoustic signals were detected is not the final resting place of the plane after an unmanned submersible found no trace of it, the search co-ordinator said Thursday.
The U.S. Navy's Bluefin 21 finished its final underwater mission in the southern Indian Ocean on Wednesday after scouring 850 square kilometres, the Joint Agency Coordination Centre said.
"The area can now be discounted as the final resting place" of the missing plane, the Australia-based centre said in a statement.
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The underwater search for the airliner, which vanished March 8 with 239 people on board en route from Kuala Lumpur to Beijing, will be suspended for a couple months while more powerful sonar equipment is brought in to search a much wider area of 56,000 square kilometres, based on analysis of satellite data of the plane's most likely course, the centre said.
That analysis has led authorities to believe that Malaysia Airlines Flight MH370 diverted sharply from its flight path and flew south to the Indian Ocean. But not a single piece of the missing Boeing 777 has been found in one of aviation's most baffling mysteries.
The news comes after the U.S. Navy dismissed an American expert's reported comments that acoustic "pings" heard in April did not come from the jet's black boxes.
CNN reported that the Navy's civilian deputy director of ocean engineering, Michael Dean, said most countries now agreed that the sounds detected by the Navy's Towed Pinger Locator came from a man-made source unrelated to the jet.
"Mike Dean's comments today were speculative and premature, as we continue to work with our partners to more thoroughly understand the data acquired by the Towed Pinger Locator," U.S. Navy spokesman Chris Johnson said in a statement, referring to Australia and Malaysia.
Dean, who is based in Washington, could not be immediately reached for comment.
In an emailed response to questions, the joint co-ordination agency said it was still examining the signals, but acknowledged: "We may never know the origin of the acoustic detections."
The agency would not yet reveal the next most likely crash site, saying that "will be made public in due course."
'Best information available at the time'
Transport Minister Warren Truss said authorities would continue to analyze the sounds that led to the initial search area.
"We concentrated the search in that area because the pings, the information we received, was the best information available at the time and that's all you can do in circumstances like this, to follow the very best leads," Truss told Parliament in announcing the search's failure.
"We're still very confident that the resting place of the aircraft is in the southern ocean and along" the course indicated by satellite analysis, he added.
Opposition lawmaker Tony Burke offered his party's condolences to the victims' families. "The hopes of many have been dashed," he told Parliament.
Officials had described the detection of four series of "pings" in the area that the satellite data indicated was the likely crash site as their best lead in the search. The signals appeared to be consistent with those from aircraft black boxes, which contain flight data and cockpit voice recordings. The locator beacons have a battery life of about a month, and the sounds were detected near the end of that expected lifespan for Flight MH370's beacons.
Earlier this week, the Malaysian government released reams of raw satellite data it used to determine that the flight ended in the southern Indian Ocean, a step long demanded by the families of some of the passengers on board. The conclusion is based on complex calculations derived largely from brief hourly transmissions, or "handshakes," between the plane and a communications satellite operated by the British company Inmarsat.
But while the 45 pages of information may help satisfy a desire for more transparency in a much criticized investigation, experts say it's unlikely to solve the mystery of Flight MH370. Theories range from mechanical failure to hijacking or pilot murder-suicide.
The families of the victims — many of whom have been highly critical of the Malaysian government and, in the absence of any wreckage, have been unwilling to accept that their loved ones are dead — had been asking for the raw satellite data for many weeks so it could be examined by independent experts. Malaysia initially balked at doing so, but then reconsidered.