Underwater sound probed in jet hunt
Australian researchers have released data about an unusual underwater sound recorded around the time Malaysia Airlines Flight 370 vanished.
But the lead scientist says the chances it is linked to the missing Boeing 777 are slim.
The low-frequency sound was picked up by underwater listening devices in the Indian Ocean off the west coast of Australia on March 8, the same day the plane disappeared on a flight from Kuala Lumpur, Malaysia, to Beijing with 239 people on board.
Researchers at Curtin University in Western Australia have been analysing the signal to see if it may be the sound of the plane crashing into the ocean.
But Alec Duncan, heading the research, said the sound appeared to have originated well outside the jet's projected flight path that officials determined based on satellite and radar data, and was therefore unlikely to have come from the plane.
"It's one of these situations where you find yourself willing it all to fit together but it really doesn't," said Dr Duncan, senior research fellow with Curtin's Centre for Marine Science and Technology.
"I'd love to be able to sit here and say, 'Yeah, we've found this thing and it's from the plane' - but the reality is, there's a lot of things that make noise in the ocean."
The noise could have come from a natural event, such as a small earthquake, Dr Duncan said. He put the chances of it being linked to Flight 370 at less than 20%.
Soon after the search for the plane moved to the southern Indian Ocean, scientists from Curtin decided to check the data from their underwater acoustic recorders off Rottnest Island, near Perth, to see if they had picked up anything of interest.
The scientists normally use the recorders for environmental research, such as studying whale sounds. This time, however, the data showed a signal that they initially thought might be the aircraft crashing into the ocean - an event that would have produced a low-frequency sound that can travel thousands of miles under the right conditions, Dr Duncan said.
The team then checked data from underwater recorders off the south-west tip of Australia that are run by the United Nations' Comprehensive Nuclear Test Ban Treaty Organisation in Vienna. One of the recorders had picked up a sound consistent with the original signal. That allowed the team to determine which direction the sound came from - though not its precise location.
The scientists then refined the data further and realised the sound originated somewhere south of India - an area well outside the arc of ocean where officials have determined the plane probably crashed.
"It's now looking as if it's unlikely to be due to the aircraft because it seems to be too far out into the ocean," Dr Duncan said, though his team was triple-checking their calculations just to be sure.
The Joint Agency Co-ordination Center, which is heading the search effort, said the Australian Transport Safety Bureau had looked at the research and was discussing it with the Curtin team.
"However, Curtin University has concluded, and the ATSB agrees, that the current results are not compatible with the international search team's analysis of the most likely area where MH370 entered the water," the agency said.
Despite a massive air and sea search, no trace of Flight 370 has been found, three months after it vanished. The search is on hold for two months while new, specialised equipment can be brought in to scour a 430x50-mile swathe of ocean where it is believed the plane crashed.