In the absence of concrete evidence, a number of theories have emerged to explain how and why Malaysia Airlines Flight 370 mysteriously disappeared on Saturday, March 8. The disappearance of the Beijing-bound flight has also generated a lot of speculation on where it is now.

At this point, there's no telling exactly what caused the Boeing 777 jetliner to vanish, along with its 12 crew members and the 227 passengers on board, but here's a roundup of some of the theories about the missing aircraft.

1. Pilot Suicide

There is a lot of speculation that the flight vanished due to what officials call "human intervention." One theory is pilot suicide. According to the Associated Press, the last time this happened was back in the 1990's when two previous plane crashes were most likely caused by pilot suicide. The first was a Silk Air crash on a flight from Singapore to Jakarta in 1997 and the other was a 1999 Egypt Air flight.

However, officials don't think the theory is strong since there is no evidence of any wrongdoing on the part of the two pilots, Zaharie Ahmad Shah, 53, and Fariq Abdul Hamid, 27, who have both been described as respectable, community-minded men.

2. Pilot Sabotage

While investigators continue to probe the pilots' backgrounds, officials are also considering pilot sabotage as recent developments suggest that an experienced pilot deliberately changed the course of the flight to a route that is well-known among navigators, reports Reuters. Inside sources told Reuters that military radar data showed an unidentified aircraft that investigators suspect was Malaysia Airlines Flight MH370 following a commonly used navigational route toward the Middle East and Europe when it was last spotted.

There were also deliberate efforts to shut off the plane's data system and transponder. 

3. Pilot error

Pilot error is another possibility although information provided by Malaysia Airlines shows the crew in the cockpit were very experienced: Capt. Ahmad Shah had 18,365 flying hours and joined the airlines in 1981, while the first officer, Fariq Abdul Hamid, joined the airline in 2007 and had almost 3,000 hours, reports USA Today.

4. Terrorism

Investigators have not ruled out the possibility that the plane was hijacked by pirates or terrorists after evidence emerged that it flew erratically and that its altitude drastically fluctuated, signaling that the person at the controls had some flight experience, the New York Times reports.

CIA Director John Brennan told ABC News that the agency is still considering terrorism and that there are already unconfirmed claims of responsibility for the plane's disappearance.

5. Mechanical Failure      

Experts are no longer convinced that mechanical failure is to blame for the missing flight because the plane was emitting signals for hours after it disappeared. Additionally, no debris has been recovered from close to the plane's last known position. 

6.  Decompression

Experts are also considering the possibility that the plane's cabin suddenly decompressed as it continued flying. According to CBS News, a decompressed chamber at high altitudes could leave everyone on board unconscious and unable to communicate with air traffic controllers. A similar incident happened in the 1999 crash that killed golfer Payne Stewart and five others.