WA researchers studying underwater sounds as part of the hunt for missing Malaysian Airlines flight MH370 say they may have detected a signal indicating a possible crash site.
Curtin University researchers said that the sound, recorded by underwater listening devices, could be related to the crash.
The Researchers had been analysing the very low frequency sound for weeks.
University Centre for Marine Science and Technology senior research fellow Alec Duncan told CNN: "One signal has been detected on several receivers that could be related to the crash.
It has been assessed to determine if it was "the impact of the aircraft on the water or the implosion of parts of the aircraft as it sank".
"But (the source of the noise) is just as likely to be a natural event," he said.
The search co-ordinators, the Joint Agency Coordination Centre, said Curtin's analysis of the signals was considered by the Australian Transport Safety Bureau.
“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,” JACC said.
“The ATSB will continue to discuss the analysis of this information with Curtin University for the purposes of informing the search.”
The researchers believe the sound came from an area thousands of kilometres northwest of the existing search site.
The signal, which was picked up by underwater sound recorders off Rottnest Island just after 9.30 am WST on March 8, could have resulted from Flight MH370 crashing into the Indian Ocean but could also have originated from a natural event, such as a small earth tremor, the researchers said in a statement
"There are large uncertainties in the estimate and it appears it is not compatible with the satellite ‘handshake’ data transmitted from the aircraft, which is currently considered the most reliable source of information."
Scientists from Curtin’s Centre for Marine Science and Technology along with colleagues from the United Nations’ Comprehensive Nuclear-Test-Ban Treaty Organisation and Geoscience Australia have been involved in the search for sounds that might help with search efforts.
Dr Duncan said a passive acoustic observatory 40km west of Rottnest Island that forms part of the Commonwealth-funded Integrated Marine Observing System had provided the potential lead.
“Soon after the aircraft disappeared, scientists at CTBTO analysed data from their underwater listening stations south-west of Cape Leeuwin and in the northern Indian Ocean. They did not turn up anything of interest,” Dr Duncan said.
“But when the MH370 search area was moved to the southern Indian Ocean, scientists from Curtin’s Centre for Marine Science and Technology decided to recover the IMOS acoustic recorders located west of Rottnest Island.
“Data from one of the IMOS recorders showed a clear acoustic signal at a time that was reasonably consistent with other information relating to the disappearance of MH370.
“The crash of a large aircraft in the ocean would be a high energy event and expected to generate intense underwater sounds.”
Dr Duncan said the signal could also have been due to natural causes – such as a small earth tremor – but the timing made it of interest in the search for MH370.
“It has since been matched with a signal picked up by CTBTO’s station south-west of Cape Leeuwin.
“A very careful re-check of data from that station showed a signal, almost buried in the background noise but consistent with what was recorded on the IMOS recorder off Rottnest,” Dr Duncan said.
“The CTBTO station receives a lot of sound from the Southern Ocean and Antarctic coastline, which is why the signal showed up more noticeably on the Rottnest recorder.
“Using the three hydrophones from the Cape Leeuwin station, it was possible to get a precise bearing that showed the signal came from the north-west.
Low frequency sounds can travel thousands of kilometres underwater, partly because sound is absorbed much more slowly in water than air and partly because the way temperatures and pressure change with depth in the ocean results in a minimum sound speed at a depth of about 1000 metres.
The Curtin University research emerges as a British sailor claims to have seen MH370 on fire as she crossed the Indian Ocean on the way to Phuket in Marcy.
The woman, Katherine Tee, said she had seen what appeared to be a plane on fire with black smoke following it the Phuket Gazette reported.
Tee was traveling with her husband Marc Horn sailing from Kochi, India to Phuket, and was on night duty when the sighting reportedly occurred.
“I thought I saw a burning plane cross behind our stern from port to starboard, which would have been approximately north to south,” Ms Tee wrote on sailing website, Cruisers’ Forum.
“Since that’s not something you see every day, I questioned my mind. I was looking at what appeared to be an elongated plane glowing bright orange, with a trail of black smoke behind it. It did occur to me that it might be a meteorite. But I thought it was more likely that I was going insane.”
Tee didn't report the sighting when she arrived in Phuket two days later because she was having marital troubles and wasn't sure of what she had seen.
“I saw something that looked like a plane on fire. That’s what I thought it was. Then I thought I must be mad. It caught my attention because I had never seen a plane with orange lights before so I wondered what they were,” she told the Phuket Gazette.