Tenerife airport disaster — Two 747s, One Foggy Runway, and a Takeoff Without Clearance

On 27 March 1977, at 17:06 local time, two Boeing 747s collided on the single runway of Los Rodeos Airport on the Spanish island of Tenerife, killing 583 people. It remains the deadliest accident in aviation history. A KLM 747, registration PH-BUF, began its takeoff roll in dense, drifting cloud while a Pan American 747, registration N736PA, was still taxiing on the same runway toward an exit it had not yet reached. The KLM aircraft, already accelerating, lifted its nose and tore through the Pan Am’s upper fuselage. All 248 people aboard the KLM died; 335 of the 396 aboard the Pan Am died. The 61 survivors, all from the Pan Am’s forward section, escaped before fire consumed both aircraft.

Neither aircraft was scheduled to be at Los Rodeos. Both had been diverted there earlier that Sunday after a bomb planted by a Canary Islands separatist group exploded in the passenger terminal at their intended destination, Gran Canaria, and a second device was reported. The diversions packed Los Rodeos — a small airport with one runway, one parallel taxiway, and no ground radar — beyond its comfortable capacity. Parked airliners blocked part of the taxiway, so departing aircraft had to taxi down the active runway itself and turn around at the far end, a procedure called backtaxiing. When Gran Canaria reopened, the controllers worked to launch the backlog into deteriorating weather, with low cloud rolling across the field and visibility collapsing from a kilometre to a few hundred metres and back within minutes.

The investigation was conducted by the Spanish Subsecretaría de Aviación Civil, with formal participation by Dutch authorities (the Netherlands Aviation Safety Board), the United States, and the operators, in accordance with the international convention governing aircraft-accident inquiry. The Spanish report, released in October 1978, placed the fundamental cause squarely on the KLM captain: he began his takeoff roll without an air traffic control clearance, did not heed the tower’s instruction to stand by, and did not stop when the Pan Am crew transmitted that they were still on the runway. The Dutch authorities, while accepting that the KLM captain had taken off prematurely, emphasised a mutual misunderstanding in the radio communications and the inherent limitations of voice radio rather than assigning blame to one man alone. KLM ultimately admitted that its crew was responsible and compensated the victims’ families.

No crime was prosecuted; both captains died in the collision and the inquiry was administrative, not criminal. What the disaster produced instead was a wholesale change in how flight crews communicate and how they work together. The accident is the founding case for two enduring reforms: standardised, unambiguous radio phraseology — the word “takeoff” reserved for an actual clearance — and Crew Resource Management, the training discipline that empowers junior crew members to challenge a captain’s error before it kills everyone aboard.