The researchers from Cardiff analysed data from hydrophones – underwater microphones – which picked up a six-second signal recorded around the time the plane is believed to have crashed intothe Indian Ocean after it ran out of fuel.
This would be large enough to be recorded by hydrophones thousands of kilometres away.
There are two hydroacoustic stations able to detect such a signal. One is in Cape Leeuwin in Western Australia and the second is in the British territory of Diego Garcia in the Indian Ocean.
They were set up as part of a surveillance regime to oversee the Comprehensive Nuclear Test-Ban Treaty. Both locations were operational around the time MH370 is believed to have crashed into the Indian Ocean.
These stations are located within tens of minutes’ signal travel time from the seventh arc, a search area 1920km west of Perth pinpointed by the last communication between a satellite and the plane.
Ten years ago, a Malaysia Airlines Flight 370, disappeared on March 8, 2014 while en route from Kuala Lumpur to Beijing with over 200 people on board. Photo / AP
Hydroacoustic stations have previously detected distinctive pressure signals from aircraft crashes, as well as earthquakes of various sizes at distances of more than 4800km.
In their research, the Cardiff University team has identified one signal that coincides with the narrow time frame when the aircraft could have crashed into the ocean on March 8. It was recorded at the Cape Leeuwin station.
But this signal was not detected at the Diego Garcia station.
“This raises questions about its origin,” said researcher Dr Usama Kadri, a reader of applied mathematics.
It is not conclusive, but he said: “Given the sensitivity of hydrophones, it’s highly unlikely a large aircraft impacting the ocean surface wouldn’t leave a detectable pressure signature, particularly on nearby hydrophones.”
His team believes further research could unlock the mystery in a similar way to how an Argentine navy submarine, the ARA San Juan, was found on the seabed a year after an implosion sent it plummeting into the depths of the South Atlantic on November 15, 2017.
They found the vessel after detonating grenades in the ocean to emulate an explosion on the submarine, then cross-referenced the signals from those with sounds picked up by hydrophones when it imploded.
As a result, they found the wreck at a depth of nearly 900m, 464km off the coast of Argentina.
“A similar exercise, using either explosions or airguns of energy levels equivalent to those believed to be associated with MH370, could be conducted along the seventh arc,” said Dr Kadri.
“If the signals from such explosions showed pressure amplitudes similar to the signal of interest, it would support focusing future searches on that signal.
“If the signals detected at both Cape Leeuwin and Diego Garcia are much stronger than the signal in question, it would require further analysis of the signals from both stations.
“If found to be related, this would significantly narrow down, almost pinpoint, the aircraft’s location.
“On the other hand, if the signals are found to be unrelated, it would indicate a need for authorities to reassess the time frame or location established by their official search efforts to date.”
Britain has already played a key part in pinpointing the search area in its role in supporting the international investigation into the missing plane which took off from Kuala Lumpur on a flight to Beijing only to apparently turn west over the Indian Ocean.
Two weeks after its disappearance, Inmarsat, a British satellite telecommunications company, revealed the plane’s satellite unit had been responding to hourly requests after it disappeared from other radars. Working with the UK Air Investigations Branch, it was able to provide investigators with a potential search area.
Over three years Australia, the United States, China and Malaysia surveyed 73,600 sq km of sea floor south-west of Perth in an area described by Tony Abbott, the then Australian prime minister, as “as close to nowhere as it’s possible to be” – an area renowned for its strong winds, hostile seas and deep ocean floors.
In 2015 and 2016, debris from the aircraft was washed ashore on several Indian Ocean islands including Reunion and on the coast of Africa. A new search was launched in January 2018 by the private contractor Ocean Infinity but, after searching for six months, it also failed to find anything.
Dr Kadri said: “The disappearance of MH370 motivated this work because it raised questions about the ability to detect aircraft crashes in the ocean, and the potential use of hydroacoustic technology to aid search and rescue efforts.
“Unfortunately, we’ve been unable to find a signal with the certainty needed to launch a new search for the missing aircraft. However, if the recommendations are followed by the appropriate authorities, we can assess the relevance of the observed signals, potentially shedding light on the location of MH370.”
