Mid-air collision
In aviation, a mid-air collision is an accident in which two or more aircraft come into unplanned contact during flight and collide with each other.
The potential for a mid-air collision is increased by miscommunication, mistrust, error in navigation, deviations from flight plans, lack of situational awareness, and the lack of collision-avoidance systems. Although a rare occurrence in general due to the vastness of open space available, collisions often happen near or at airports, where large volumes of aircraft are spaced more closely than in general flight.
The deadliest mid-air collision occurred on 12 November 1996, when a Boeing 747 operated by Saudia collided with an Ilyushin IL-76 operated by Kazakhstan Airlines near Charkhi Dadri, India. The crash, in total, killed all 349 people.