MH370, which had been travelling from Kuala Lumpur to Beijing, disappeared on March 8, 2014, with 239 people on board. The Boeing 777 aircraft last communicated with air traffic control at 1.19am when the plane was flying over the South China Sea, before vanishing from civilian radar screens. Over the years, the captain – Zaharie Shah – has come under fire amid claims suggesting he went on a suicide mission after analysis of radar data suggested he made a “final goodbye” gesture.
However, air crash investigator Christine Negroni believes this move was not on purpose.
She claims it was the erratic, illogical thoughts of a pilot who had been starved of oxygen, following a fire in the cockpit.
She wrote on her blog in 2018: “To me, that insensible action [the turn] is a bright and shining clue that the pilots’ actions were illogical because they were incapable of logical thought.
“My scenario is that the plane depressurised at 35,000 feet.
An air crash investigator noticed a “bright and shining” clue
MH370 went missing in 2014
To me, that insensible action [the turn] is a bright and shining clue that the pilots’ actions were illogical because they were incapable of logical thought.
“The first officer, alone in the cockpit, put on his emergency oxygen mask but failed to get 100 percent oxygen under pressure which would be required to restore his intellectual acuity.
“Instead, with the insidious feeling of wellbeing that characterises hypoxia – or oxygen starvation – the pilot turned the plane back towards Kuala Lumpur.”
Ms Negroni went on to detail what she believed happened next.
She added: “He knew there was a problem but didn’t have the brain processing power to act appropriately.
“This explains why he turned in one direction then another before passing out as the plane headed into the world’s most remote sea.”
Ms Negroni’s theory singles out First Officer Hamid as the one in control of the plane when disaster struck.
However, others – using the same hypoxia idea – have centred their beliefs around Mr Shah being in control.
Former pilot Christopher Goodfellow claims the change in route was carried out on purpose as the veteran captain attempted to land at Langkawi International Airport in Malaysia.
He wrote in a blog post in 2014: “The turn [back across Malaysia] is the key here.
“Zaharie Shah was a very experienced senior captain with 18,000 hours of flight time.
Zaharie Shah has come under fire
Fariq Hamid may have taken control of the plane
“We old pilots were drilled to know what is the closest airport of safe harbour while in cruise.
“Airports behind us, airports abeam us, and airports ahead of us – they’re always in our head, always.
“If something happens, you don’t want to be thinking about what are you going to do, you already know what you are going to do.”
Mr Goodfellow went on to explain why Langkawi could have been a possible option for Mr Shah.
He added: “When I saw that left turn with a direct heading, I instinctively knew he was heading for that airport.
“He was taking a direct route to Palau Langkawi, a 13,000-foot airstrip with an approach over water and no obstacles.
“The captain did not turn back to Kuala Lumpur because he knew he had 8,000-foot ridges to cross.
“He knew the terrain was friendlier toward Langkawi, which also was closer.”
However, hypoxia is just one line of questioning among dozens of theories about what could have happened to MH370.
MH370 had 239 people onboard
A flaperon was discovered on Reunion Island
While more outrageous theories have claimed the plane was a “flying bomb” due to the cargo of five tonnes of mangosteens and 221kg of lithium-ion batteries.
Aviation expert Clive Irving has suggested these two items could have somehow combusted and created a deadly plume of smoke that filled the cabin.
He said in 2015: “The cargo hold has a special liner intended to contain a fire until it is extinguished.
“A battery fire might well have been intense enough to breach the liner and, in doing so, allow the airflow to weaken the concentration (and therefore the effectiveness) of the Halon gas used as a fire suppressant.
“The organic electrolyte in lithium-ion batteries decomposes at high temperatures, generating very toxic fumes typically containing compounds of fluorine and even arsenic.”
There have also been arguments over how the plane could have hit the Indian Ocean.
The official investigation states the jet spiralled out-of-control, hitting the water at pace and splitting into thousands of pieces.
However, aviation expert Larry Vance claims Zaharie Shah actually performed something known as a “ditching”.
He theorised this following the discovery of a part of the plane’s wing, known as the flaperon, on Reunion Island.
He told Australia’s 60 Minutes investigation team in 2017: “I think the fuselage is certainly intact somewhere on the bottom of the Indian Ocean.
“When the flaperon was found, everyone should have concluded this was a human engineered event.
“There’s no other explanation.
“The reason we don’t see lots of debris is because it remained in the fuselage and that remains at the bottom of the water.”
Bruce Margolis, a veteran Boeing 777 pilot, demonstrated during in a flight simulator Mr Vance’s theory.
He said during the simulation: “The physical evidence from the recovered wing part suggests the pilot tried to keep it intact in a controlled ditching.
“The engines are going to hit first and they’ll be ripped off – the noise would [have been] terrible.
Larry Vance believes the plane was brought to a controlled stop
The relatives of MH370 passengers hope to find out the truth
“But it’s very easy to control the aircraft, you can virtually have your hands off.”
The simulator then struck the water, before floating along.
Mr Margolis said: “Bang – that’s it – in the water – the engines are ripped off, but there’s a chance the fuselage is intact.
“And if it’s in one piece it could actually keep floating for a while before it starts sinking.”
In 2016, he faced a backlash after Australian officials confirmed he had practiced a route where the plane is said to have vanished using an in-flight simulator he had built at home.
The simulator information shows only the possibility of planning.
A spokesman said: “It does not reveal what happened on the night of its disappearance nor where the aircraft is located.
“For the purposes of defining the underwater search area, the relevant facts and analysis most closely match a scenario in which there was no pilot intervening in the latter stages of the flight.”
Despite this, the Malaysian Government have ruled out the possibility of any wrongdoing on Mr Shah’s part.