The deadliest aircraft accident is the collision of the two Boeing 747s of the flight companies KLM and PanAm at Tenerife in March 27, 1977. 583 people died in this event, while only 61 passengers and crew personnel survived it.
Tenerife disaster: Collision between KLM and PanAm Boeing 747's at Tenerife. Sunday, March 27, 1977. Los Rodeos, Tenerife's North airport is, unfortunately, famous for the fateful accident which occurred on March 27, 1977, in which 583 people died when KLM and Pan Am 747s collided on a crowded, foggy runway in Tenerife, Canary Islands. The incident remains the world's worst aviation accident in history.
Many contributing factors, lead up to the crash, but the probable cause, cited by the Air Line Pilots Association (ALPA, 1978), was the KLM pilot taking off without takeoff clearance.
What happened on the Tenerife runway? Quite simply put, the KLM attempted takeoff, even though the Pan Am was still on the runway and the KLM had not received clearance for takeoff. The Pan Am tried to get out of the way and the KLM tried to climb over, but the latter ended belly up after dragging its tail on the ground. The lower fuselage of the KLM plane hit the upper fuselage of the Pan Am plane, ripping apart the center of the Pan Am jet nearly directly above the wing.
1. Neither plane should have been at Los Rodeos in the first place, which was not used to handling the traffic it had that day. They should have been in Gran Canaria, but a terrorist bomb attack by Canary Island separatists, The Canary Islands Independence Movement, closed the airport there.
2. There was fog with poor visibility at Los Rodeos. That didn't help anyone, least of all the Pan Am who was looking for a suitable exit off the runway. The one they had been advised to take, seems an impossible turn for a 747.
3. The pilot of the KLM, Captain van Zanten, their "top man", seems to have been in some considerable hurry to get going and appears to have held a level of authority that subordinates did not dare challenge with the necessary strength.
4. Analysis of the cockpit voice recorder (CVR) transcript showed that the KLM pilot was convinced that he had been cleared for takeoff, while the Tenerife control tower was certain that the KLM 747 was stationary at the end of the runway and awaiting takeoff clearance.
5. Reading the transcript of the radio transmissions, exchanges between the tower and the planes were ambiguous at best. One contributing factor to the accident at Tenerife was the involved parties’ use of non-standard phraseology during the critical moments leading up to the accident.
6. The crucial communication that might have prevented the KLM from taking off was lost in radio squelch. The congestion that results from using a single channel radiotelephone system can also lead to communications which are either missed or blocked by the transmissions of other users (Kerns, 1991, 1999). This problem of blocked transmissions was apparent in the runway collision at Tenerife in the Canary Islands, when the air traffic controller and the Pan Am pilot both tried to contact the KLM pilot at the same time.