This story was originally published in February 2021 in Technology & Economy. In honor of the turn of the year, it will also be published in Tivi.
The captain never meant that his children would fly the plane without the help of an autopilot.
It was March 22, 1994, carrying 63 passengers and 12 crew members Aeroflotin slow 593 From Moscow to Hong Kong traveled steadily over Siberia. Airbus The A310-300 passenger plane had settled at a cruising altitude of 10,100 meters.
Due to the length of the flight, the aircraft had a three-man flight crew instead of two: The actual captain was on rest, and the aircraft was piloted by another captain and a co-pilot.
Around 00:40 local time, guests came to the cockpit: a 13-year-old daughter of a second captain, a 15-year-old boy and an Aeroflot pilot on board. The investigation report does not reveal all the discussions in the cockpit, but a few minutes later the captain said to his daughter:
“Would you like to come sit in my seat?”
Then he got up from the captain’s seat. This was already illegal, as the regulations require the pilot-in-command to always formally notify the monitoring pilot (in this case the co-pilot of the aircraft) that the latter should take control.
The daughter sat in the captain’s seat for a few minutes until the captain decided to demonstrate to her the operation of the autopilot. The captain put the autopilot in the lateral steering mode in HDG / SEL mode, where the direction of the aircraft is changed using the knob on the control panel.
The captain first turned the knob to the left, at which point the plane began its left turn. He then turned the knob to the right, turning the plane toward the flight path programmed into the computers. Shortly afterwards, the captain selected the autopilot’s NAV mode, at which point the aircraft returned to follow the route line.
The end result was a small extra bend in the journey. The daughter sat in the captain’s seat for about seven and a half minutes, after which she made room for her big brother.
A couple of minutes to get to the boy asked a fatal question:
“Can I turn the joystick?”
The captain then intended to introduce the operation of the autopilot in the same way as to the little sister, with the difference that the boy had been allowed to touch the joystick.
“Turn left,” the father urged his son. So he gave his son permission to pilot the plane.
The boy turned the steering wheel to the left, and soon after that the captain turned the autopilot direction knob in the same direction. The machine tilted to the left. Next, the captain turned the direction knob to the right to return the plane back to the route, and finally turned the autopilot NAV mode back on.
However, the captain’s son still held on to the joystick, and the joystick’s movements now resisted the steering commands given by the autopilot. As the inconsistency increased beyond the planned threshold, the autopilot safety mechanism turned off the lateral steering. The autopilot’s main switch was still on, and its second channel – altitude control – was operating normally.
Neither of the pilots — the captain standing behind the left-hand pilot’s seat and the coxswain sitting still in place — noticed, so virtually no one steered the plane sideways. (Switching off the autopilot caused a warning sound on the aircraft type, but the lateral steering alone was switched off silently.)
Accident investigators also said the coxswain was holding the joystick at the time of the incident, but the forces exerted by the pilot on the boy’s steering system prevented the coxswain from noticing what had happened to the autopilot.
The machine started lean to the right, which confused the boy still sitting in the captain’s seat.
“Why is it turning around?”
“Does it turn on its own,” the captain asked.
For a while, the pilot duo and the third Aeroflot pilot in the cockpit considered the reason for the operation of the aircraft. They estimated that the autopilot was piloting the plane into a waiting pattern.
In the meantime, the machine had already tilted about 50 degrees to the right. A large jet passenger plane like the Airbus A310 is not designed for steep curves at high altitudes, so the kinetic energy of the aircraft was rapidly reduced.
The autopilot, which was still on, was trying to keep the plane at cruising altitude, with the result that the angle of attack of the plane began to rise and the risk of stalling increased.
When the mate woke up to the situation, he reacted by turning the steering wheel sharply to the left. This was not the right way to fix the situation, but first the coxswain would have had to turn off the autopilot, then reduce the angle of attack by pushing the rod forward and only then correct the curve of the machine.
The boy, still sitting in the captain’s seat, held on to the second joystick of the plane, making the situation of the coxswain even more difficult. Accident investigators later found out that in the situation, the coxswain’s mobile seat had been pushed almost to the rear, and therefore only a 160-centimeter-long coxswain had difficulty steering the plane.
The stall warning began to sound and the autopilot turned itself off. The pilots had lost their sense of posture, the plane was almost on its right side and it crashed where the speed began to increase dramatically.
At the same time the captain tried to get back to his own seat as the plane moved uncontrollably. Before he succeeded, the coxswain desperately tried to straighten the plane, but as a result of violent steering movements, the plane went into a downward spiral.
When the captain got back in place, the plane was almost upright. For the last minute, he tried to take control of the machine without success.
The plane crashed into the ground near the city of Mezhdurechensk, was completely destroyed and everyone involved was killed.
According to the final report, warning systems that were more sensitive to changes in autopilot operating conditions or unusual machine positions could have helped pilots notice the situation earlier, but the accident was mainly caused by the captain’s actions.
Source: Tivi by www.tivi.fi.
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