5 Theories About What Happened to Missing Malaysia Flight

March 18, 2014— -- Each day that passes without a clear idea of what happened to missing Malaysia Flight 370 new theories and possibilities are proposed about the possible fate of the jet.

Among the most recent theories proffered are a fire that disabled the plane, that it hid by flying in the "shadow" of another plane, or that everyone on board was overcome when the plane's cabin became depressurized.

Here are five of the most repeated theories of what happened to flight MH370:

Flight 370 Caught Fire

This theory found renewed interest this week after pilot Chris Goodfellow's Google Plus post went viral. His theory posits that a fire is the cause of the disappearance, not hijacking or other nefarious motives.

The fire could have filled the cockpit with smoke, prompting the pilots to try and fly to the nearest airport (accounting for the plane's sudden turn west) and shutting down electrical systems trying to figure out the cause of the fire (which he argues could account for the transponders being shut down). The crew could then have been overtaken by smoke and died on board, leaving the plane to fly until it ran out of fuel and crashed.

The Jetliner Flew in Another Plane's "Shadow"

Experts have suggested that if the crew shut off all of the plane's communication systems with air traffic control, they could have continued flying in another jet's "shadow," either above or underneath another commercial airliner.

Pilot Keith Ledgerwood posted a blog that has gained attention this week suggesting that the plane flew beneath or above a Singapore Airlines flight going in the same direction at the same time of night. With MH370's transponder off, trackers on land would believe that whatever plane they saw was the Singapore Airlines plane because its transponder would have been transmitting. Ledgerwood posits that Flight 370 shadowed the Singapore Airlines plane over India and then landed somewhere on the far side of India near Pakistan or Afghanistan without being detected by radar.

Depressurization Happened Aboard the Plane

Proper air pressure on board a plane is mechanically maintained when a plane is over 8,000 feet above sea level, an altitude that lowers the amount of oxygen in the blood. If there were an air leak, or the plane flew too high or someone intentionally fiddled with the craft in some way, it would have had detrimental effects, experts told ABC News today.

"What happens first is your brain is not as quick. You'd get very confused and stop thinking clearly," said Randy Padfield, a licensed pilot with more than 10,000 hours of flying experience and the CEO of Aviation International News. "Then you'd fall asleep and eventually die due to lack of oxygen."

In this theory, depressurization could have happened accidentally and overtaken all on board, or it could have been purposefully done by someone at the controls seeking to kill those on the plane.

The Jet Exploded in Mid-Air

Because there has been no debris found floating in the ocean, some theorists have said the plane could have broken up at 35,000 feet, spreading miniscule pieces of wreckage into the sea that would be too difficult to spot. A bomb could have cause the plane to disintegrate mid-air.

The Plane Was Shot Down by Another Country's Military

Others have speculated that Flight 370 was accidentally shot down by a missile from another country's military, which did not recognize the plane as a civilian aircraft and fired at it. The United States mistakenly shot down an Iranian passenger plane in the 1980s, an incident referred to frequently in recent days in speculation about MH370