Nick Vivion
USA TODAY
March 7, 2015

It’s been one year since the tragedy of missing Malaysia Airlines flight 370 unfolded in disbelief. How could an airliner in today’s jet age simply disappear without a trace? Of course, like any widespread mystery, there are many theories about what happened on that fateful day. Here’s a rundown of what could have happened to MH370:

Sabotage, or the “rogue pilot” theory

This has become the predominant theory due to recent analysis by former Boeing 777 pilot Byron Bailey. According to the Telegraph, he suggests that the pilot was able to deftly thread through country borders in order to avoid raising suspicion with nearby flight controllers, leading Bailey to conclude:

It doesn’t take Sherlock Holmes to work out who did it. Nearly all my colleagues in the aviation industry realised within days of the crash that only a pilot could have done this.

Facts that support this deliberate diversion theory include that someone turned off the plane’s transponder and disabled the communications system within the cockpit. This is a sophisticated move that most agree could only be done by a trained pilot rather than a malfunction or amateur hijacking. The question of motivation is still left unanswered, but it could have been simple suicide, says science writer Ewan Wilson. A 777 pilot, Bailey also points out that a suicide attempt by the pilot would void any life insurance payments to family, which would be a real incentive for such an elaborate scheme.

Hijacking

There was some discussion of two Iranian passengers traveling with forged documents as potential hijackers. However, this theory was deflated by reports that they were seeking asylum. Writer Jeff Wise believes this theory to be most valid: Someone turned the power off and then on again for the satellite communication system, which is under a bay near the galley and unreachable without leaving the cockpit. The pilot would have had to leave the cockpit to achieve this, and pilots are not generally trained to do this. This following video also shows how technically complicated it would be to identify the correct circuit to cycle the power of the satellite system:

This theory is also disputed by the fact that emergency squawk codes — or transponder codes used in case of emergency — were not deployed by the pilots, and also that there were no unusual communications from the plane.

Loss of cabin pressure due to mechanical failure

This theory works well to address the reasons for the plane’s long journey on auto-pilot. According to estimates, the plane would have been able to fly for 7 hours on autopilot before running out of gas. A rapid loss in cabin pressure would have rendered the pilot’s unconscious, and the plane would have kept going, gradually descending and crashed into the ocean with minimal surface debris.

However, it doesn’t account for the transponder being turned off, and the precise way in which the airliner was maneuvered.

American conspiracy to kill Chinese intelligence workers

Jim Stone is a freelance journalist that operates a conspiracy-rich website, and suggests that America was responsible for wiping out the plane:

“They nailed that plane which was unusually full of key people for the sole purpose of getting the NSA back into a position of completely raping Chinese data and regaining total information superiority.”

This is an extension of Stone’s theory that MH370 was somehow swapped with MH17, the plane that was shot down over the Ukraine close after the disappearance of MH370. We’re not buying it.

Insurance scam

One Malaysian police chief continues to suggest that the plane’s disappearance could be due to amassive insurance fraud scheme. Police chief Khalid Abu Bakar said to the media:

“Maybe somebody on the flight has bought a huge sum of insurance, who wants family to gain from it or somebody who has owed somebody so much money, you know, we are looking at all possibilities.”

While there are no clear answers, the documentary below from Smithsonian Channel explores the enduring mystery.