A new theory says the pilot of Malaysia Airlines Flight MH370 was likely behind the plane's disappearance. In the image, a young girl holds a balloon with a message during a memorial event for the missing Malaysia Airlines flight MH370, in Kuala Lumpur, March 3, 2018. Getty Images/Manan Vatsyayana

A retired United Airlines pilot has claimed that missing Malaysia Airlines Flight MH370 caught fire before it crashed into a remote part of the southern Indian Ocean on March 8, 2014. Speaking to the Daily Star, Captain Ross Aimer said he believed the lithium-ion batteries in the cargo of the Boeing 777-200 ignited shortly after the plane took off from Kuala Lumpur.

According to Aimer's theory, Flight MH370 most likely continued to fly for hours while on fire, even after everyone on board the plane was already dead. He said the jet's auto-pilot system could have continued its flight despite the jet being on fire, until it ran out of fuel and went down. Aimer said he based his theory on the analysis of the position of the plane's flaps.

"The fire may have started during or shortly after take off, since things started to happen as soon as they levelled off. It is possible the fire killed everyone onboard then continued burning the aircraft until it crashed. Since the flaperon was discovered in the ocean, it most probably crashed into the ocean."

The Australian Transport Safety Bureau (ATSB), which was leading the investigation into the plane's disappearance, said the flaps were likely in a "retracted position at the time they separated from the aircraft making a controlled ditching scenario very unlikely."

Aimer said that the "flaps basically proved that whatever happened to the airplane, it did hit the water with the flaps up, meaning no one was in control of it in that moment." He added: "The fire damage probably would not have reached out to the wings and the flaperon... It's a huge aircraft, and a fire would have been inside the hall of the aircraft so no, most probably it would not have reached out there.

"It's a good possibility that if the fire consumed some of the aircraft but it was still flyable – because it's a huge airplane – the pilots and passengers were incapacitated and it flew until it ran out of fuel and just crashed into the ocean somewhere... Most probably these guys were on auto pilot, and the auto pilot just continued flying it."

However, Aimer's claim could not be verified as he did not have any concrete evidence to back his claim.

The Malaysian Transport Ministry said in its final report in July the plane likely crashed after running out of fuel. However, it said investigators were unable to determine the cause of the crash.

Despite a multimillion-dollar search in the southern Indian Ocean lasting four years, the plane's main body could not be found. The mystery behind the plane's disappearance continues as the families of the 279 people on board the plane still await closure.

Several theories have emerged since the plane went missing while on its way to Beijing. The theory of the lithium-ion batteries' explosion in the cargo of the jet is not new and had been previously suggested. Some theorists also claimed the pilot of the plane took the aircraft into a "death-dive" in a murder-suicide incident. Rumors of a hijack also surfaced in the days following the plane's disappearance. However, none of these claims have been confirmed.

Meanwhile, some independent searchers recently tried to locate the missing plane with the help of satellite images. British investigator Ian Wilson pinpointed a location in a jungle in Cambodia on Google Maps, saying it was the resting place of the jet. He also went on a ground search of the area in October to back his claim, but had to abort the mission due to dangers in the path leading up to the alleged location of the wreckage.

Last month, an aviation expert claimed MH370's fuselage was lying almost completely intact at the bottom of the southern Indian Ocean.

British aviation expert Daniel Boyer also claimed last month he located the missing plane's fuselage, tail and the cockpit in the same area where Wilson had found the plane on Google Maps. However, these claims could not be confirmed.