It's rare for pilots to intentionally crash commercial airliners but Tuesday's Germanwings jet crash in the French Alps is not the first where suspicion falls on a pilot.
Pilot suicide is among the various theories concerning last year's mysterious disappearance of Malaysia Airlines Flight 370. Here are other examples:
Nov. 29, 2013: A Mozambique Airlines plane crashes in northern Namibia, killing all 27 passengers and six crew. A preliminary investigation points to a deliberate act by the captain after he locked the co-pilot out of the cockpit.
Oct. 31, 1999: EgyptAir Flight 990 crashes into the Atlantic Ocean after taking off from New York's John F. Kennedy International Airport. All 217 on board are killed. U.S. investigators say the co-pilot cut power to the engines, turned the plane downward and repeated the phrase, "I rely on God." Egyptian officials have rejected the findings and say the crash may have been caused by a problem in the tail.
Dec. 19, 1997: SilkAir Flight 185 plunges into a river in Indonesia, killing all 104 aboard. U.S. investigators say the captain probably crashed the plane on purpose, but an Indonesian investigation was inconclusive.
Aug. 21, 1994: A Royal Air Maroc flight crashes into a mountain after takeoff from Agadir, Morocco. All 44 aboard are killed. Commission investigating the crash says pilot intentionally plunged the plane to the Earth because he wished to commit suicide. The flight union disputes that finding.
Feb. 9, 1982: A Japan Airlines jet crashes into Tokyo Bay on approach to Haneda Airport. Twenty-four of the 174 people on board were killed. The crash was blamed on the captain, who was later declared mentally unstable.
The Associated Press