Tenerife airport disaster

On 27 March 1977, two Boeing 747 passenger jets collided on a runway at Los Rodeos Airport (now Tenerife North–Ciudad de La Laguna Airport) on the Spanish island of Tenerife, killing 583 people and injuring 61 others in the deadliest accident in aviation history. The incident occurred at 17:06 GMT (UTC +0) in dense fog, when KLM Flight 4805 initiated its takeoff run, colliding with the right side of Pan Am Flight 1736, which was on the runway.

Source: Wikipedia — Tenerife airport disaster (CC BY-SA 4.0)