The last contact flight controllers had with flight 370 was over Pulau Perak, a small island in the Straits of Malacca. That location is hundreds of miles from the planned flight path between Kuala Lumpur and Beijing.
A senior Malaysian Air Force official spoke to CNN about the investigation on the condition of anonymity because he is not allowed to discuss the case with the media. According to this official, the flight was not only hundreds of miles off course but had also changed directions and was flying in the opposite direction of its destination before its disappearance.
The plane's transponder -- which emits identifying transponder codes to help flight controllers track a plane's route progress -- stopped working around the same time flight controllers lost contact with the pilots, the official said.