The worst accident in the history of commercial aviation (excluding the World Trade Center tragedy) was caused by a stupid and avoidable pilot error.
I am referring to the Tenerife disaster. On March 27, 1977, two KLM and Pan Am Boeing 747s collided on the runway at Tenerife airport, resulting in the deaths of 583 people.
Strictly speaking, it was not a “crash” from an aircraft, as the accident occurred on the ground, but the story behind it is worth mentioning.
That day, a bomb exploded at Gran Canaria airport, near Tenerife, and the threat of new bombs ended up diverting several aircraft heading from Gran Canaria to Tenerife. Among the diverted flights were the Pan Am 1736 and KLM 4805, which would later be the protagonists of the disaster.
The Tenerife airport, which was not prepared for the movement of aircraft that would follow, was crowded with planes parked on the taxiways . They, their crews and their passengers were waiting for Gran Canaria airport to reopen. Meanwhile, a dense fog was forming on the track (which was a common event in Tenerife).
When the possibility of another bomb on Gran Canaria was ruled out, aircraft “stuck” on Tenerife were finally given permission to take off. As the taxiways were crowded, it was not possible to use them to go to the headland in use. Aircraft would need to adhere to a procedure called backtaxiing to take off: enter the runway in the opposite direction to takeoff and landing, use it as a taxiway , go to the threshold in use, make a 180º turn and then take off.
The captain of the Boeing 747 operating KLM Flight 4805, Jacob Van Zanten, decided to refuel the aircraft before leaving Tenerife, which delayed its takeoff. This was a source of great frustration for the 747 crew operating Pan Am Flight 1736 as the KLM plane was in its path. The Pan Am 747 couldn’t take off if the KLM 747 didn’t get out of the way.
After a long 30 minutes, the KLM 747 finally began to taxi towards the threshold in use. The Pan Am 747 was instructed to follow. At that point, the intense fog allowed a horizontal visibility of only 500 meters on the ground, so that the flight controllers could no longer see the taxiing aircraft and the Pan Am could no longer see the KLM in front of it.
When both aircraft were on the runway, the Pan Am 747 received an instruction to leave the runway at the third exit (one of several small connections between the runway and the airport apron), while the KLM 747 continued to head towards the runway. do b acktaxi . However, the crew was confused by the instruction, as the third exit was unfeasible for a 747. Also, the pilots were not sure how many exits they had already passed, so they ended up continuing towards the fourth exit.
After the taxi, Van Zanten, the KLM pilot, slightly accelerated the throttles. He wanted to take off soon, at all costs, before weather conditions (especially visibility) deteriorated and prevented the flight. His co-pilot, Klaas Meurs, inquired that they still did not have air traffic control clearance to take off. Van Zanten then pulled back the throttles and impatiently ordered him to apply for clearance.
Air traffic control authorized the route that the aircraft would take after takeoff, but not takeoff, as the Pan Am 747 crew had not yet confirmed that it had left the runway, and of course the KLM 747 could not start the flight. take off with another 747 in its path. However, Van Zanten ignored the lack of authorization, put full power on the throttles and began takeoff.
In the following seconds, it is possible to hear the Pan Am crew telling the air traffic control that they would advise when clearing the runway. The flight engineer of KLM 4805, Willem Schreuder, surprised, asked Van Zanten if the other 747 had already left the runway. The answer he got was affirmative, but deep down Schreuder knew that Van Zanten had taken off without authorization and that something was not right.
This was the end result:
Of course, in fact, a combination of several factors was responsible for the accident, and not a mere isolated incident. It’s always like that in plane crashes, multiple factors. However, it is undeniable that none of this would have happened if Van Zanten had a little more patience.
Interestingly, he was one of the most important figures at KLM at the time, and the company, upon learning of the accident, appointed him as leader of the investigation team. But then they found out that he was already involved in the accident… in another way…
Anyway. It was stupid and avoidable.