Scientists are investigating an underwater sound signal which they say could have been caused by Malaysian Airlines flight MH370.
The signal was detected by sound recorders usually used to monitor whales near Rottnest Island, off the coast of Western Australia.
It was picked up just after 1.30am on 8 March, the day the aircraft bound for Beijing from Kuala Lumpur disappeared with 239 people on board.
A cautious Dr Alec Duncan of Perth Curtin University Centre for Marine Science and Technology warned the noise could also have been caused by a natural event, such as an earth tremor.
He said: “Soon after the aircraft disappeared, scientists at CTBTO (United Nations’ Comprehensive Nuclear-Test-Ban Treaty Organisation) analysed data from their underwater listening stations south-west of Cape Leeuwin and northern Indian Ocean. They did not turn up anything of interest.
“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.
“The crash of a large aircraft in the ocean would be a high energy event and expected to generate intense underwater sounds.”
While the signal was recorded off the coast of western Australia, the original location of the noise is believed to be around 3,000 miles north-west of the country – placing the point of origin just off the southern tip of India.
Speaking to the New York Times, Dr Duncan added: “It’s not even really a thump sort of sound – it’s more of a dull oomph.
“If you ask me what’s the probability this is related to the flight, without the satellite data it’s 25 or 30 per cent, but that’s certainly worth taking a very close look at.”
Although pings matching the frequency of those from a black box recorder were identified by search crews, no debris has been found.
Adding to the uncertainty is an account by a British yachtswoman who this week claimed she may have seen the missing plane on fire.
Katherine Tee was travelling across the Indian Ocean in May when she saw what she believed was a plane on fire crossing the night sky, trailing a plume of black smoke behind it.
She told the Phuket Gazette: “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.
“I could see the outline of the plane, it looked longer than planes usually do. There was what appeared to be black smoke streaming from behind it.”