1977-03-27
KLM Royal Dutch Airlines / Pan American World Airways
Flight KLM 4805 / PA 1736
Departure
Amsterdam Airport Schiphol, Amsterdam, Netherlands
Destination
Gran Canaria Airport, Las Palmas, Spain
Causation Breakdown
Recurrence Likelihood Today
Very Low
The specific conditions — uncontrolled congestion at a small airport, ambiguous ATC language, and no ground radar — have been systematically addressed through mandatory CRM training, ICAO phraseology standards, read-back requirements, and ground movement radar at major airports. A direct repeat is considered very unlikely.
Summary
The Tenerife disaster remains the deadliest accident in aviation history. A bomb threat at Gran Canaria Airport diverted hundreds of flights to the small Los Rodeos Airport. In dense fog and amid confused radio communications, KLM 4805 began takeoff without clearance and struck Pan Am 1736 taxiing on the same runway. The crash directly triggered a revolution in cockpit communication standards and crew resource management training.
Cause & Investigation
Determined cause
Runway collision
Both aircraft had been diverted to Los Rodeos Airport, Tenerife due to a bomb threat at Gran Canaria. While taxiing in heavy fog, KLM Flight 4805 began its takeoff roll without receiving ATC clearance, and collided with Pan Am Flight 1736, which was still on the active runway. The KLM captain misunderstood a communication to mean takeoff clearance had been granted.
Investigation body
Spanish Civil Aviation Authority (Subsecretaría de Aviación Civil) with participation from Dutch and US authorities.
Timeline & Safety Improvements
Flight KLM 4805 / PA 1736 disaster
Boeing 747-206B / Boeing 747-121 operating for KLM Royal Dutch Airlines / Pan American World Airways. 583 fatalities, 61 survivors.
Formal investigation opened
Conducted by: Spanish Civil Aviation Authority (Subsecretaría de Aviación Civil) with participation from Dutch and US authorities.
Cause determined: Runway collision
Both aircraft had been diverted to Los Rodeos Airport, Tenerife due to a bomb threat at Gran Canaria. While taxiing in heavy fog, KLM Flight 4805 began its takeoff roll without receiving ATC clearance, and collided with Pan Am Flight 1736, which was still on the active runway. The KLM captain misunderstood a communication to mean takeoff clearance had been granted.
Improvement implemented
Standard phraseology 'take-off' was restricted exclusively to the actual takeoff clearance to eliminate ambiguity.
Improvement implemented
Mandatory read-back of all runway clearances was implemented globally.
Improvement implemented
Crew Resource Management (CRM) training was introduced industry-wide, directly stemming from this crash.
Improvement implemented
ICAO standardized English as the required language for all ATC communications.
Improvement implemented
Ground radar and runway incursion alert systems were accelerated in development.