The mystery of MH370 remains 5 years later — here are all the theories, dead ends, and unanswered questions from the most bizarre airline disaster of the century

On March 8, 2014, Malaysia Airlines flight MH370 vanished from air traffic control radar screens, never to be seen again and in the process spawned the most incredible aviation mystery of the 21st century.

The 239 people on board were never found, and are presumed dead.

Investigations dedicated to finding the plane, the victims, or any substantial evidence of what really happened, have come up with next to nothing, inviting speculation and conspiracy to fill the vacuum.

In July 2018, the Malaysian government, which has taken chief responsibility for investigating the disappearance, issued what it claims is its final report on the fate of the plane.

Transport minister Anthony Loke has promised total transparency in the document, with no redactions or obfuscations but it wasn't able to answer the fundamental question of what happened to the plane. French authorities even started a new probe in a bid to find out what really happened.

Here's what we know, what theories have been put forward, and the unanswered questions that remain.

A normal take-off, "good night" then nothing

Malaysia Airlines flight 370, a Boeing 777, left Kuala Lumpur at 12:41 a.m. local time on March 8, 2014. 239 people were on board.

The majority more than 150 were Chinese. The rest included 38 Malaysians, seven Indonesians, six Australians, and individuals passengers from a host of other countries including France and the US. Twelve crew members were on board as well.

The final voice communication from the cockpit came less than an hour after takeoff: "Good night Malaysian three seven zero."

The plane then stopped communicating with ground control.

It deviated from its planned route two hours after takeoff, according to data from military radar.

For reasons that are still unknown, the plane abruptly left its planned route and turned back in the direction of Malaysia, then on towards the Indian Ocean. This map shows where it went before dropping off the grid:

There were no reports of bad weather or distress calls.

The plane traveled south and may have changed altitude at some point. The plane sent out a final, automated satellite communication that was received but did not contain any information about where it was.

Other aircraft communications had been purposefully disabled earlier or somehow powered down in the flight, authorities said. The plane had disappeared.

The search attempts

Search attempts were quickly launched, but with little idea of where to start, and a vast swathe of territory where the plane could feasibly be.

Teams from Singapore, Vietnam,and Malaysia were searching the waters off Vietnam which is partway between Kuala Lumpur and Beijing around 12 hours after contact was lost.

FBI team and Interpol personnel flew to assist the operation, with a total of nine contributing to the initial search.

40 ships worked around the clock and 34 aircraft flew during daylight hours. A total of 26 countries pitched in, as the search area was repeatedly widened. They found nothing.

The next step began on May 5, 2014 79 days after the plane went missing.

Malaysia, Australia, and China announced their agreement to hold an underwater search. At the request of the Malaysian government, the investigation was led by the Australian Transport Safety Bureau. But it discovered little.

Malaysia officially declared the disappearance to be an accident in January 2015 327 days after it vanished.

A report one year after the disappearance gave a detailed picture of delays and protocol violations before the search was launched.

It revealed that five hours and 13 minutes passed between the last communication from the plane and Kuala Lumpur's first distress signal about the disappearance, and that another five hours passed before the first search flights took off to try and find it.

The Malaysian government's final report , released on July 30, 2018, said that authorities "cannot determine with any certainty" why the plane disappeared. The key finding was that the plane's sharp diversion at 1.25 a.m. was done manually, but it is still unclear who was responsible for the maneuver.

Malaysia's civil aviation chief resigned after the report found that air traffic control did not comply with standard procedures.

The first fragment

The first actual piece of MH370 took more than a year to find. It was a fragment of the plane's wing, which washed up in July 2015 on Runion island, thousands of miles from Kuala Lumpur.

After a four-month hiatus to allow for detailed mapping of the sea bed , the search resumed in October 2015, but bad weather continued to slow the investigation.

The two-year anniversary report in March 2016 shed no more light on what had happened.

By May 2016 more than 105,000 sq km (65,240 miles) of seafloor in the southern Indian Ocean had been covered, leaving just 15,000 sq km (9,320 miles) left to look at.

In July 2016, the Dutch company hired by Australian authorities to lead the search said it may have been looking in the wrong part of the sea for the past two years.

Families became so frustrated that they launched their own organized search for debris in Madagascar.

The fruitless search was suspended in January 2017, after $145 million was spent. Officials then concluded that the probable crash site was farther north.

In the year that followed, organizations like Australia's chief science agency released reports while analysis of satellite imagery and debris continued as talks to formally begin a new search continued.

The Malaysian government started the latest search in January 2018 in partnership with US-based private firm Ocean Infinity.

The search covered 112,000 sq km (43,243 sq miles) in the southern Indian Ocean, including a25,000 sq km (15,534 sq mile) target area that had not been searched before. It was called off on May 29 with no new significant new findings, even though investigators still wanted to search further north.

In five years of searching, the only confirmed traces of the Boeing 777 aircraft have been three wing fragments washed up on Indian Ocean coasts: in Madagascar, Runion Island, and Tanzania.

Prime Minister Mahathir Mohamad has said Malaysia would consider resuming the search if new clues came to light.

The theories so far

The lack of answers even as more information comes to light, combined with the fruitless search efforts, means all that is left are theories of what might have happened to the flight some more plausible than others. Some theories have been dismissed by authorities, but others continue to loom large.

The theory considered by the Malaysian government and the Australian Transport Safety Bureau, is that the passengers and crew of MH370 were incapacitated by an oxygen deficiency .

This theory speculates that the whole plane, including captain Zaharie Ahmad Shah, somehow fell unconscious. The plane would have run on autopilot after it ran out of fuel, before crashing into the sea. Versions of this theory include a deliberate hijacking in which someone damaged the oxygen supply or some kind of accident that harmed the planes mechanics and affect the plane's oxygen levels.

In another version of this theory, Shah was the only one awake. In a suicidal state, he disabled communication before steering the plane into the ocean. A team of analysts on Australian current affairs programme "60 Minutes" came to this conclusion.

Others also support the theory that the act was a deliberate one by the pilot. ACanadian aviation expert and former airplane crash investigator told Canada's CBC news in May 2018 thathe could state with"100 per cent certainty" that the incident was caused by a pilot in a murder-suicide.

But the July 2018 report offered evidence against the idea that it was a deliberate act by the crew.

The 495-report document said neither the pilot nor the first officer showed psychological signs suggesting they could have deliberately crashed the plane.

According to both family members and work associates for the crew, "there were no behavioral signs of social isolation, change in habits or interest, self-neglect, involvement in drug or alcohol abuse" in any staff on the plane.

Investigators also said that the crew's movements captured on CCTV before the flight and their voices on air traffic control recordings did seem any different to how they were on previous flights.

Dr. Kok Soo Chon, the lead investigator, told reporters at a press conference on the report that the men exhibited "no anxiety or stress." He said the report was ultimately "not ruling out anything" but found plenty of evidence against the suicide theory.

A former pilotChristopher Goodfellowspeculated that the plane had experienced an electrical fire and turned back towards Malaysia to try to find an emergency landing strip.

According to Goodfellow, the plane would have flown on autopilot as the fire incapacitated the crew and passengers.

But another pilot, Patrick Smith, has cast doubt on this theory , as it would have been unlikely that the plane would travel for hours on autopilot after a fire. The plane also turned back for a secondtime after it headed towards Malaysia.

Smith told Business Insider in 2015 that the nature of the debris found might suggest that the airline was under control when it crashed.

The plane may have landed gently into the water, and sunk in mostly one piece. Experts have previously said that this theory is consistent with the debris found. This would mean that the plane had a low-energy crash or else a gentle, deliberate landing in the ocean.

Another theory is that the search has taken place in the wrong area investigators should be looking north of Malaysia, rather than Australia. Perhaps, this theory suggests, the plane crashed or even landed and was hidden somewhere. But it was rejected by Inmarsat, the British company that owned and operated the satellite that tracked MH370 until it dropped off the network.

A theory refuted by the July 2018 report was that a mixture of batteries and fruit in the plane's cargo had somehow formed an explosive mixture that brought down the plane.

Other theories claimed that the plane was taken over "remotely" in a bid to foil a hijacking. Malaysias prime minister Mahathir Mohamad suggested this in May 2018, but did not state who he believed had done it. The 2018 report said that there was no technology on the plane that would allow control to be remotely taken from the pilots.

The details that first emerged as the planes disappearance was reported from the fact that two people boarded with stolen passports and no one seemed clear if everyone had boarded the plane meant that conspiracy swirled. Conflicting accounts from officials and families accusing the Malaysian government of withholding information added fuel to this fire.

More outlandish theories include a remote cyber hijacking, the plane being shot down, the idea that Russian president Vladimir Putin knows the planes location, a mystery extra passenger taking control of the plane, a Bermuda Triangle-style area causing the planes disappearance, North Korea taking the plane, and the US military shooting it down.

Other theories blame the CIA, Israel, and aliens, all traditional bogey men for conspiracists.

Unanswered questions

So much information remains unknown, despite the efforts of the largest and most expensive underwater search in history.

If the plane's route can somehow be established by a future probe, or the plane itself is found, it could provide clues as to whether the plane was deliberately heading somewhere, or an if an accident took place.

More basic information is still not known. We don't know if there was a case of oxygen deprivation, or if there was an accident on board, or it was a deliberate action. We don't know which one of the pilots was flying the plane when it disappeared, or whether it was someone else, which would help answer the question of whether the incident was a hijacking.

It may be that even if the plane is found, these questions would remain unanswered.

Relatives had pinned their hopes on the Malaysian government's last report, which concluded that it didn't hold the answers.

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The mystery of MH370 remains 5 years later — here are all the theories, dead ends, and unanswered questions from the most bizarre airline disaster of the century

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