On March 27, 1977, two Boeing 747 passenger jets collided on the runway at Los Rodeos Airport (now Tenerife North Airport) on the Spanish island of Tenerife.
The collision occurred when KLM Flight 4805 initiated its takeoff run while Pan American Flight 1736 was still on the runway. The impact and resulting fire killed everyone on board KLM 4805 and most of the occupants of Pan American 1736, with only 61 survivors in the front section of the aircraft.
Investigation revealed that there was communication misinterpretation and false assumptions.
As a consequence of the accident, sweeping changes were made to aircraft, international airline regulations, and cockpit procedures. Aviation authorities around the world introduced requirements for standard phrases and a greater emphasis on English as a common working language.
With 583 fatalities, the disaster is the deadliest accident in aviation history.