Tenerife Tragedy: 583 Die in Deadliest Aviation Disaster

The KLM pilot never received takeoff clearance. On March 27, 1977, KLM Flight 4805 began its takeoff roll on the main runway at Los Rodeos Airport in Tenerife while Pan Am Flight 1736 was still taxiing on the same runway in heavy fog. The two Boeing 747s collided at approximately 160 knots, killing 583 people in the deadliest accident in aviation history. Only 61 passengers on the Pan Am aircraft survived; no one on the KLM plane lived. Both aircraft had been diverted to the small Canary Islands airport after a bomb threat closed their intended destination, Las Palmas. Los Rodeos had only one runway and one parallel taxiway, and both 747s, along with several other diverted aircraft, were parked on the taxiway, blocking it. When Las Palmas reopened, the 747s were instructed to taxi up the runway itself and turn off at designated exits. Dense fog reduced visibility to under 300 meters. KLM Captain Jacob Veldhuyzen van Zanten, one of the airline's most experienced pilots and the face of its advertising campaigns, was anxious about crew duty-time limits that would strand his aircraft if they did not depart quickly. He advanced the throttles and began the takeoff roll before receiving explicit clearance. His flight engineer questioned whether the Pan Am aircraft had cleared the runway, but van Zanten continued. The Pan Am crew, unable to find their assigned turnoff in the fog, was still on the runway when the KLM 747 slammed into them at rotation speed. Tenerife transformed aviation safety. The disaster led to standardized phraseology that eliminated ambiguous language like "okay" from air traffic communications, mandatory Crew Resource Management training that empowered junior officers to challenge captains, and ground radar requirements at major airports. Every pilot who has ever said "unable" to a captain in a cockpit is living in the safety culture that Tenerife's 583 deaths created.