Both jets had been diverted to the small airport after a bomb exploded at Gran Canaria's terminal. As fog rolled in, KLM Flight 4805 began its takeoff run without clearance while Pan Am Flight 1736 was still taxiing on the same runway. All 248 people on the KLM plane died, along with 335 of the 396 aboard the Pan Am jet. The disaster reshaped cockpit culture, leading to standard radio phrases and training that encourages junior crew to challenge captains.
March 27, 1977, began with a bomb planted by Canary Islands separatists at Gran Canaria airport, which forced dozens of flights to divert to Los Rodeos on neighbouring Tenerife. The airport had a single runway and a crowded apron, and by afternoon it was jammed with large jets. When Gran Canaria reopened, the KLM crew refuelled to save time later, and cloud was drifting across the field.
The Pan Am jet was told to taxi down the runway and leave by the third exit; in the murk its crew missed it and kept going. At the far end, the KLM captain, Jacob Veldhuyzen van Zanten, one of the airline's most senior pilots, advanced the throttles. His flight engineer asked whether the Pan Am plane was clear of the runway. The captain replied emphatically that it was. Radio transmissions from the tower and Pan Am overlapped, producing a squeal that blocked the key warnings.
The KLM jet lifted off too late and tore through the top of the Pan Am aircraft at about 160 miles per hour. Sixty-one people survived, all from the Pan Am jet's front section. Investigators blamed misunderstood radio calls, and the industry responded by standardising phrases and teaching crews to speak up.
Key people: Jacob Veldhuyzen van Zanten, Victor Grubbs