On March 27, 1977, two Boeing 747 passenger jets, KLM Flight 4805 (from Amsterdam to Gran Canaria Airport) and Pan Am Flight 1736 (from New York to Gran Canaria Airport), collided on the runway at Los Rodeos Airport (now Tenerife North Airport), on the Spanish island of Tenerife, Canary Islands, killing 583 people, and making it the deadliest accident in aviation history.
A terrorist incident at Gran Canaria Airport had caused many flights to be diverted to Los Rodeos, including the two accident aircraft. The airport quickly became congested with parked aircraft blocking the only taxiway and forcing departing aircraft to taxi on the runway instead. Patches of thick fog were also drifting across the airfield, preventing aircraft and control tower from seeing each other.
The collision occurred when KLM 4805 initiated its takeoff run while Pan Am 1736, shrouded in fog, was still on the runway and about to turn off onto the taxiway. The impact and ensuing fire killed everyone on board the KLM jet and most of the occupants of the Pan Am, leaving only 61 survivors from the aircraft’s front section.