A preliminary scan of computers belonging to the pilots of missing Malaysia Airlines Flight 370 did not turn up anything that would indicate they were planning to hijack the plane, U.S. officials told CNN Tuesday.
The flight simulator owned by pilot Zaharie Ahmad Shah did not show any of the flight deviations. U.S. officials have listened to previous communications from the pilot and his first officer and heard nothing suspicious that would shed light on that fateful night, CNN also reports.
1. The autopilot computer-programmed theory
The New York Times is reporting that a government official says Malaysia Airlines Flight 370's turn to the west was programmed into the autopilot. If true, that means that either it was done by the pilots or someone else with detailed knowledge of the avionics in the 777 cockpit.
The last voice communication from the plane occurred at 1:19 a.m., when someone responds to air traffic control "All right, good night." Investigators say that voice appeared to be the co-pilot's. Two minutes later, the transponder stopped transmitting.
Now, Thailand says that it tracked an unknown object on radar that traveled west toward Indonesia just minutes after the transponder stopped broadcasting, and investigators say satellite pings from the plane continued for seven hours after it disappeared.
CNN reports those facts seem to support the hypothesis that the plane made a left turn from it's scheduled route and traveled west across the Malay Peninsula and out into the Indian Ocean.
However, it is unknown why that turn was made, or who was at the controls at the time.
2. The fire onboard theory
While not necessarily a new theory, a pilot has laid out what he thinks caused Flight 370 to vanish: A fire.
The commercial pilot, Chris Goodfellow, who wrote out his theory for Wired, conjectured that the crew was dealing with a small fire after takeoff and that the turn to the west was made in an attempt to land at the nearest airport. The crew could have become incapacitated, or killed, by the smoke before they could land, and the autopilot continued on its last course until it ran out of fuel somewhere in the Indian Ocean.
Fires have caused passenger airliners to crash in the past. In 1998, for example, a Swiss Air flight crashed off the Canadian coast when a fire broke out on board. The pilots tried to put the fire out by shutting off electronics, but were overcome with smoke, and the plane crashed into the Atlantic Ocean.
Goodfellow explains that the communications system blackout of Flight 370 could be either the result of the fire, or of the crew shutting down various systems trying to diagnose the problem. Other 777 pilots say that shutting systems down is not how crews would handle an electrical fire.
3. The 'unlawful human interference' theory
However, former Malaysia Airlines Captain Nik Huzlan, who has flown the very plane that disappeared many times, told CNN "the lack of communication is really, really puzzling" if the plane encountered a mechanical problem. He told CNN's Kyung Lah he thinks there was "some unlawful human interference" on board.
4. The shadow flight theory
A blogger has put forward the theory that the plane turned west to link up with another 777 flying from Singapore to Barcelona, Spain.
Keith Ledgerwood theorizes in his blog that the flight turned west to tuck into the radar shadow of Singapore Airlines flight 68. He speculates that Flight 370 flew close enough to the Singapore Airlines jet with its transponder off that they would appear to be just one plane on radar.
He says it might be possible for the Singapore flight to not know it was being shadowed, because 777 does not have radar behind it.
Then somewhere over Central Asia, Ledgerwood says, Flight 370 could have broken off to land unnoticed.
Pilots say that, in theory, Ledgerwood's hypothesis is possible, but it would be incredibly difficult for one commercial plane to catch another at night and stay in close formation for a long period of time. They also say it's improbable that Flight 370 would not have been picked up sometime during that night by some country's radar.
Many countries are continuing to work together to tackle a search area about the size of the continental United States. China and Kazakhstan say they are taking a lead role in the search along the "northern arc" of the last satellite "ping," looking for the plane or wreckage.
Australia is heading up the search along the southern arc, in the Indian Ocean.
There is some concern, because if the plane did crash in the water, the black boxes will only have power to send out sonar pings for another few weeks. If the wreckage is not found by then, the black boxes may never be recovered.
Meanwhile, Courtney Love thinks she may have solved the mystery. The rocker tweeted this out Monday:
— Courtney Love Cobain (@Courtney) March 17, 2014
That area was one of the first and most heavily searched areas. Crews have found nothing they can link to the missing Malaysia Airlines flight.