US investigators are considering sabotage in the disappearance. According to Malaysian investigators, two of the plane’s navigational systems were disabled. US investigators believe a third system, located on the plane’s lower deck, was also compromised. Within an hour into the flight, the plane’s transponder was disabled, almost certainly from inside the cockpit. Radar was then unable to track the plane. The ACARS navigation system was also disabled; doing so would require computer access and “expert knowledge,” though not necessarily limited to Boeing 777-trained pilots.
After this point, the only indication that the plane was in the air came from satellite pings, which show that the plane remained aloft for some five hours, probably traveling westward over the southern Indian Ocean, before also losing contact. The most likely scenario after the loss of satellite signal, US investigators say, is that the plane crashed into the ocean. However, a less likely scenario has the plane again changing course and flying on for another hour (at most) to an unknown destination. If that scenario occurred, it would have taken two people and access to the restricted lower deck’s electronics bay to disable satellite communication.