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Air Crash Investigation File

Human factors come first

  From 1950 to 2010, among the 1,085 air crashes for which the exact cause of the accident has been identified, human factors accounted for 80.5% of the accident causes, of which crew causes, operating procedures and maintenance factors accounted for 62%, 15% and 3.5% respectively. Human factors involve many aspects such as the quality of pilots, whether training is in place, whether aircraft maintenance personnel and air traffic control personnel at the airport control tower operate in accordance with regulations and so on. Statistics show that pilot errors account for up to 50% of the factors that cause fatal air accidents. There are many reasons for pilot error, such as fatigue driving, negligence and poor coordination. There is also a physiological factor worthy of attention, that is, the flight illusion produced when driving at high altitudes, such as the incorrect perception of the aircraft’s spatial state, position, motion and flight environment. At this point, if the pilot is not aware of it, there will be catastrophic consequences. In the event of an emergency, pilots are the last line of defense and they can prevent many possible accidents.
  On the evening of March 27, 1977, an air crash occurred on the Spanish island of Tenerife that shocked the world. Two Boeing 747s full of fuel and personnel collided and exploded on the runway, killing a total of 583 people in the deadliest air accident in human history. In the hours before the incident, Tenerife was very peaceful. At 13:15 on the same day, a bomb terrorist attack occurred at Las Palmas International Airport on the nearby island of Gran Canaria. Due to the advance warning, the airport was evacuated in time and only eight people were injured. Soon after, the airport staff received a call saying that there was still a bomb, and for safety reasons, they began to close the evacuation and conduct a comprehensive search. All flights that were supposed to land at Las Palmas International Airport were diverted to Los Rodeo Airport on the island of Tenerife. The airport is small, with only one runway and limited apron capacity. The influx of diverted flights was dense and chaotic.

Los Rodeo crash

  Among them, KLM flight 4805 took off from the Netherlands at 9:31, carrying 235 passengers. After a 4-hour flight, it was supposed to land at Las Palmas International Airport, but now it can only be crowded in Los Rodi European Airport. KLM stipulates that for flight safety and to prevent fatigue driving, it strictly limits the working hours of the crew in a flight mission, and everyone will be severely punished if they exceed the limit. Seeing that the time limit was about to be exceeded, Captain Jacob van Zanton was very disturbed. He decided to fill up the plane while he was waiting so he wouldn’t have to refuel for the rest of the flight.
  Not far away, Victor Grub, the captain of Pan Am Flight 1736, was equally anxious. He didn’t want to stop at Los Rodeo, because takeoffs and landings are the easiest to miss. Considering the brief closure of Las Palmas International Airport, Victor Grubb asked for the airliner to be allowed to hover directly above. Control tower air traffic controllers denied his request and ordered him to land at Los Rodeo.
  At around 16:00 that day, Las Palmas International Airport reopened, and the planes staying at Los Rodeo Airport were ready to take off again. But at this time, fog gradually enveloped the airport, and visibility became very low. Because the passengers of Pan American Airlines did not disembark and waited in place, they had the privilege of taking off first. The aircraft is parked at the end of the runway and needs to taxi to the start of the runway. Victor Grubb found that the huge KLM passenger plane in front of him was blocking his way. There was only one runway and there was no way to get around it, so he had to wait for the passengers of KLM to re-board before taking off.
  At 16:56, the control tower air traffic controllers allowed the KLM passenger plane to taxi to the runway, and the Pan Am passenger plane was also allowed to follow it to the runway. The runway has exits C1, C2, C3 and C4. Air traffic controllers told the Pan Am to leave the runway at Exit C3 (the third exit from the left) and circle the outside to the runway takeoff point. The Pan Am had taxied past exit C1 when the air traffic controller issued the order. Captain Victor Grubb understood “the third exit from the left” as “the third exit further forward”, which is the C4 exit. He did not report to the control tower to confirm the suspicious situation, and went to exit C4 to leave.
  On the other side, the KLM passenger plane taxied to the runway take-off point and turned 180°. The co-pilot radioed the air traffic controller to request takeoff, and received a command feedback of “airline navigation clearance after takeoff”, but not “takeoff clearance”, which are absolutely different. However, Captain Jacob van Zanton was in a hurry to take off and misunderstood the air traffic controllers, thinking the takeoff had been authorized. Before waiting for the co-pilot to repeat, he replied: “We are taking off.” The captain’s English with a strong Dutch accent made the air traffic control personnel at the time hear “We are taking off” as “We are taking off”, so Reply: “Okay! Stand by, we will notify you!”
  Just as the air traffic control staff spoke the second half, the radio signal happened to be interrupted by the Pan Am report “We are still taxiing on the runway” . The control tower and the Pan Am were talking at the same time, causing high-frequency noise from the KLM’s radio equipment, and the crew only heard a “OK”. At 17:03, the Pan Am passenger plane had come to the C4 exit and was about to turn away. The first officer suddenly noticed that the landing lights of the KLM passenger plane far away from the runway were shaking, and it was getting closer and closer. The KLM plane was actually accelerating. However, there were only 9 seconds left before the two planes collided. The Pan Am captain, Victor Grubb, immediately pushed at full speed and wanted to turn his head and dash into the lawn next to him, but it was too late. The KLM passenger plane was accelerating and preparing to take off at this time, but there was no plane in front of it. It was not until 3.16 seconds before the impact that they finally saw the Pan Am airliner that was desperately dodging in the thick fog ahead. Captain Jacob van Zanton couldn’t help but exclaimed: “Oh my God!”
  The captain of the KLM airliner, Jacob van Zanton, responded in a timely manner and tried his best to make the plane roll over and climb. The takeoff angle was so large that it even cut a deep ditch on the ground. However, the fuselage filled with oil was heavy and difficult to lift. Although it flew off the ground within about 100 meters of the Pan Am, the nose successfully passed the Pan Am, but the engine and the lower half of the fuselage The main wheel still collided with the upper right fuselage of the Pan Am passenger plane at a speed of about 260 km/h, and tore the middle section of the Pan Am passenger plane. The KLM plane continued to climb, but the impact ripped off the left outer engine, and a large amount of debris was sucked into the left inner engine and damaged the wing. The plane then stalled, rolled violently, and fell on the runway from 150 meters in the air, sliding 300 meters due to inertia. In an instant, the KLM passenger plane with its full fuel tanks exploded into a ball of fire, almost incinerating the entire plane. The Pan Am passenger plane, which was violently hit, burst into flames in an instant, and the entire plane broke into several pieces. Only the left wing and the tail of the plane retained their general appearance afterwards.

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