What happened to MH370? Every theory about missing flight 10 years on

Ten years after the disappearance of flight MH370, British scientists say they have detected a signal that could unlock the mystery.

Una mujer escribe un mensaje en un panel durante un acto para conmemorar los 10 años de la desaparición del vuelo MH370 de Malaysia Airlines, en un centro comercial en Subang Jaya, en las afueras de Kuala Lumpur, Malasia, el domingo 3 de marzo de 2024. (AP Foto/FL Wong)
A woman writes a tribute on the 10th anniversary of the disappearance of flight MH370 earlier this year. (AP Photo)

A team of British scientists say they have detected a signal that could help solve the mystery of missing flight MH370.

It is more than 10 years since the Malaysia Airlines flight carrying over 200 passengers disappeared in one of the most perplexing mysteries of modern times.

The Boeing 777 was carrying 227 passengers, more than 150 of them Chinese, and 12 crew members when it disappeared from radar less than 40 minutes after take-off from Kuala Lumpur, Malaysia, en route to Beijing, China, on 8 March 2014.

Extensive search operations were carried out in the years that followed, with various debris from the aircraft washing up on beaches in the Indian Ocean, but the plane has never been located and the reason behind its disappearance has never been established.

But now researchers at Cardiff University have analysed data from underwater microphones, or hydrophones, which caught a six-second signal recorded near the time the plane is believed to have crashed.

They want to carry out further tests to see if the sounds can help finally locate the plane, The Telegraph reported.

PUBLIKA, KUALA LUMPUR, KL, MALAYSIA - 2018/03/03: A MH370 poster seen at the 4th Annual MH370 Remembrance event. 

Hundreds of people had gathered at the Remember MH370? Its Not History, Its Our Future is the 4th Annual MH370 Remembrance event organised by VOICE370 the MH370 Family Support Group held at Publika, Kuala Lumpur on 3rd March 2018. The purpose of the event is to gather the people to stand in solidarity and commemorate 4 years since tragedy of MH370 disappeared from the blue sky with the loss of 239 lives on 8th March 2014. (Photo by Faris Hadziq/SOPA Images/LightRocket via Getty Images)
There are a number of theories about the disappearance of Malaysia Airlines flight MH370. Getty Images)

Two hydroacoustic stations able to detect a signal were in operation around the time the plane disappeared - one in Cape Leeuwin in Western Australia and another in the British territory of Diego Garcia in the Indian Ocean.

The team at Cardiff University says it has identified one signal recorded at Cape Leeuwin that coincides with the time frame of the plane's disappearance.

On the 10th anniversary in March, Malaysia's transport minister Anthony Lake said US seabed exploration company Ocean Infinity had been asked to discuss its latest search proposal after two previous failed attempts. Malaysian prime minister Anwar Ibrahim said his country would reopen the investigation into the disappearance if compelling new evidence was found.

Yahoo News UK examines the previous theories put forward about what happened to MH370.

The most widely proffered theory is that the plane's pilot, Captain Zaharie Ahmad Shah, 53, from Penang, Malaysia, deliberately crashed the aircraft.

A preliminary report by the Malaysian government in March 2015 said there was no evidence of financial irregularities or behaviour changes among its pilots of crew.

However, a report by New York Magazine the following year claimed Shah had conducted an exercise on his home flight simulator less than a month before the ill-fated flight that closely matched the path it would take through the southern Indian Ocean.

In this Tuesday, April 1, 2014 photo made available Thursday, April 3, 2014, crewmen on a Royal New Zealand Air Force P-3 Orion Rescue Flight 795 search for debris from the missing Malaysia Airlines Flight MH370 in southern Indian Ocean, 1,500 kilometers (932 miles) northwest of Perth, Australia. No trace of the Boeing 777 has been found nearly a month after it vanished in the early hours of March 8 on a flight from Kuala Lumpur to Beijing with 239 people on board. (AP Photo/Kim Christian, POOL)
The crew on a Royal New Zealand Air Force P-3 Orion Rescue Flight 795 search for debris from the missing flight MH370 in the southern Indian Ocean in April 2014. (AP Photo)

However, investigators from the Australian Transport Safety Bureau (ATSB) said this in itself was not unusual.

The Atlantic reported that friends of Shah said he was "lonely and sad" and suffering from depression in the lead-up to the flight. This theory posits that Shah switched off communications with air-traffic controllers, put on his oxygen mask and depressurised the plane, causing those on board to die from a lack of oxygen (hypoxia).

Another theory is that one of the pilots or passengers hijacked the plane with the intention of landing it and then escaping, but the plan failed and they suffered hypoxia with the rest of those on board.

The plane's co-pilot was First Officer Fariq Abdul Hamid, who, at 27, was relatively inexperienced, and MH370 was his final training flight. However, investigators said there was no evidence to suggest that the pilot or co-pilot had any conflicts or problems between them.

A relative reacts during an event held by relatives of the passengers and supporters to mark the 10th year since the Malaysia Airlines flight MH370 carrying 239 people disappeared from radar screens on March 8, 2014 while en route from Kuala Lumpur to Beijing, in Subang Jaya on March 3, 2024. (Photo by Arif Kartono / AFP) (Photo by ARIF KARTONO/AFP via Getty Images)
A relative reacts during a 10-year anniversary event held by relatives of the passengers of MH370 in Subang Jaya, Malaysia. (AFP via Getty Images)

The 10 members of the plane's cabin crew were all married with children, which investigators believed ruled them out of any potential hijacking plot.

There were two Iranian passengers on the plane travelling on stolen Italian and Austrian passports, but it appears they were asylum seekers trying to get to China rather than take over the plane. Another passenger who worked as a flight engineer for a jet charter company was briefly considered as a potential hijacker but this was later dismissed.

One theory is that Russian terrorists hijacked the plane after climbing into the Main Equipment Centre (MEC) under the first-class cabin and took over the aircraft, faked location data and flew to Kazakhstan, but this has been ruled out.

MH370 was carrying more than 10,000kg of cargo in its hold, including 221kg of lithium-ion batteries, which was considered of interest to Malaysian investigators trying to figure out what happened to the flight.

The batteries, which can cause fires if they overheat and ignite, were being shipped by Motorola from a facility in Bayan Lepas, Malaysia, to Tianjin, China.

They were packaged under International Air Transport Association (IATA) guidelines but did not go through any additional security checks at Kuala Lumpur International Airport before being loaded onto the plane.

Plane wreckage believed to be from Malaysia Airlines flight MH370 is displayed during an event held by relatives of the passengers and supporters to mark the 10th year since the Boeing 777 aircraft carrying 239 people disappeared from radar screens on March 8, 2014 while en route from Kuala Lumpur to Beijing, in Subang Jaya on March 3, 2024. (Photo by Arif Kartono / AFP) (Photo by ARIF KARTONO/AFP via Getty Images)
Plane wreckage believed to be from flight MH370 is displayed during an event in Subang Jaya, Malaysia, held by relatives of the passengers and supporters to mark the 10th year of its disappearance. (AFP via Getty Images)

Another theory is that the batteries somehow mixed with more than 4,500kg of mangosteens, a tropical fruit that was also being shipped, causing combustion, but a report said it was "highly improbable" the two items would have been in contact with another as they were wrapped and in separate containers.

In another theory, the US government is accused of jamming the plane's communications before shooting it down because it did not want China to have the Motorola equipment, but this has also been dismissed.

There is a theory that a stowaway sneaked on board MH370 with the intention of bringing the plane down.

There was an underfloor area just outside the flight deck door in which someone could hide, but the stowaway would needed to have accessed the plane before it was prepared for departure.

They would also have had to overcome the cabin crew, the pilots and any intervening passengers in order to take over the plane.

The Australian Transport Safety Bureau (ATSB) said an unresponsive crew or hypoxia event was more likely than an in-flight upset (for example, a stall) or a glide event such as engine failure or fuel exhaustion.

In this photo released on Friday, Aug. 7, 2015 by the French Army Communications Audiovisual office (ECPAD) crew members looks out of the airplane door aboard a CASA 235 plane from the 181st Air Detachment of the French Air Force taking part in the search for wreckage from the missing MH370 plane off the coasts of the French island of La Reunion. A French search plane lifted off Friday for a bird's-eye view of Reunion Island, seeking any more potential debris from Malaysia Airlines Flight 370. French authorities said Friday they've launched a one-week-long operation with boats and aircraft scouring the Indian Ocean island, where a wing fragment was discovered nine days ago. (Patrick Becot/ECPAD via AP)
Searches for the missing MH370 plane have spanned a number of years. (AP Photo)

It said an uncontrolled drop in the cabin pressure from human error or structural failure leading to an unresponsive crew or hypoxia "best fit the available evidence" for the period of five hours in which the flight travelled south over the Indian Ocean without communication or significant deviation, likely on autopilot.

However, experts have not come to a consensus on this theory, but investigators said they believe the plane was not being successfully controlled when it crashed.