3. Sudden catastrophe Aviation experts initially suspected that something sudden and horrific happened. Perhaps a bomb on board, or some type of failure with the engines or airframe.
But if that were the case, debris would have been found in the spot where the transponder went off.
Also, the Boeing 777 has just one fatal crash in its 19-year history — last year's Asiana Airlines crash in San Francisco.
If there was a sudden breakup, pieces of the plane would have been visible on radar.