chronology of events
23:48. The crew of flight SU821 underwent a pre-flight medical check-up in Moscow and received permission to fly the aircraft. The commander of the aircraft is 34-year-old Rodion Medvedev, whose total flight time is about 4 thousand hours, more than 1000 of which are on aircraft of this type. Medvedev was assisted by 43-year-old Rustem Allaberdin as co-pilot, and his total flight time was almost 9 thousand hours, but he managed to fly only 276 hours in this type.
23:55. Medvedev analyzed the aircraft’s condition, weather data, aircraft load, aviation information and made the decision to conduct the flight.
23:59. One of the plane passengers sends an SMS message to his friend before starting the engine. He is afraid because the commander “has the voice of a completely drunk man.”
01:13. Aeroflot Nord Boeing 737 departed from Moscow to Perm. In addition to two pilots, there are 82 passengers and 4 flight attendants on board. 61 of the passengers are Russian citizens, many Azerbaijanis and Ukrainians fly with them, and there are also citizens of Western European countries. On board is Gennady Troshev, the famous general of the first and second Chechen wars, who commands the combined Russian forces.
01:40. The climb went smoothly, the flight at 9100 meters went smoothly.
02:45. As it approaches Perm, the plane begins to descend. He will need to perform a series of maneuvers to get on the landing route. Pilots are preparing for landing according to MH 4A procedure.
02:46. The Perm airport controller directed the aircraft via long-range position beacon code 705 PX. It served as the initial approach point to runway 21 with a landing path of 212°. Thus, the controller ordered the landing order according to the pattern MH 4B (“B” in radio communications is pronounced like “Boris”).
02:50. The crew is confused. The dispatcher directed them not to the route they were expecting, but to a longer and more complex route. As it turned out later, this was done so that another aircraft – Lufthansa’s Airbus A319 – could fly to Frankfurt am Main. “So what will happen to Boris? What’s different about Boris?” — asks co-pilot Medvedev.
02:51. The crew listened to the dispatcher’s explanation of how to fly and then asked: “Give me the route.” In response, the dispatcher replied: “We are heading towards the drive.” This command can be interpreted in two ways and in essence canceled the approach according to the MH 4B scheme. The crew became angry and continued to monitor the MH 4A model for a while.
02:52. There is a series of chaotic but technically normal maneuvers. As a result, the crew descends by maneuvering on their own, without any planning.
02:53. Pilots wonder what route the plane should take to “enter” the runway. They follow the vaguely formulated command of the controller, which cancels the flight according to MH 4B. The pilots did not make a new request or clarify the procedure.
02:54. “2-1-2 approach ready when command given for third,” says the pilot. “Understood, follow 2700 for now, route driving,” the dispatcher replied. In reality, this dialogue makes no sense because the controller and the pilot mean different things.
02:56. The error in determining the location by the on-board computer exceeded 4.5 km. This may occur due to the natural “disengagement” of the inertial navigation system or due to an error in the navigation setting before the flight.
02:57. Medvedev and Allaberdin argue over which direction to turn. The commander thinks it’s on the left, the co-pilot thinks it’s on the right. The argument is interrupted by the controller, who tracks the plane’s movement on radar and instructs it to turn right. Once again, he did not specify which route the plane would take to land, and the pilots began to discuss this issue.
02:58. The autopilot makes an unexpected left turn because the assigned route point cannot be reached. “Where did he go ***? I don’t understand where I went? – asks Allaberdin.
02:59. Automatic traction control, which regulates the operation of the engines, is turned off due to the fulfillment of a number of conditions according to the program. Pilots see a warning about this and begin to manually control the engines. In this case, a difference in thrust occurs, that is, the right and left engines create different forces. The crew does not attempt to eliminate the difference in thrust or compensate for it with rudder (“pedals”). Instead, they try to stabilize the plane with roll control (tilting the wings left and right).
03:01. Pilots begin to slow down using spoilers (retractable “spoilers” on the wings). Since the speed was reduced without the landing gear deployed and almost no wings extended, the automation signaled an error. The commander gets angry and looks for a way to turn it off: “Where is this button ***?”
03:03. The controller was confused by the height of the plane: “Are you descending? It reads 1800 for me.” Thereupon, the commander asked the following question: “How far should we descend? How low should we go? From this moment on, the crew began to act increasingly nervous.
03:03. Pilots are trying to figure out how autopilot works. “Why doesn’t he come down?” [я] The clicked title is selected,” Allaberdin asked. In response, the commander began to explain that the direction selection mode has nothing to do with altitude control, that LVL CHG must be selected to descend.
03:06. Due to the thrust difference, the aircraft’s roll reached 32° to the left. The co-pilot disrupted the functioning of the autopilot by manually leveling the plane. At the same time, by order of Medvedev, engine thrust was adjusted almost to maximum.
03:07. Due to the increased speed, the plane begins to gain altitude and Allaberdin eventually turns off the autopilot. The crew loses control over the flight parameters and changes the plane’s pitch randomly.
03:07. The dispatcher states that the altitude has risen to 900 meters. Additionally, realizing that the aircraft cannot land based on its current direction and position, the controller gives the command to return and calculates a repeat of the approach.
03:08. Medvedev moved the steering wheel sharply, tilting the plane 50° to the right. BANK ANGLE warning signal sounds. The co-pilot asks with fear: “Where?” What are you doing?!” And the crew levels the plane.
03:08. The commander confirmed the dispatcher’s order for another approach several times, but did not carry it out and continued to confer with the dispatcher as if he was not planning a second approach. Embarrassed by inappropriate behavior, the dispatcher asked: “Is everything okay with your crew?”
03:09. The last minute of the flight. The aircraft slowly turns left and reaches 30°. The co-pilot flying the plane asks the commander: “Take this!” Take it!” Medvedev responded to this: “What the fuck ***, I can’t either!” A second later, the commander is still trying to stabilize the plane, but only increases the turn angle to 76°. “On the contrary, in the other direction! Your mother! – Allaberdin is shouting. All this time the BANK ANGLE signal is heard.
The commander takes control and the aircraft begins to turn sharply, alternately right and left. “What are we doing ***” the co-pilot says desperately. After Medvedev turns the control wheel all the way to the left, the plane almost rotates around its axis and begins to fall. After that, only obscene swearing and screams were heard in the cabin.
All people on board died.
Caused?
According to IAC research, the direct cause of the disaster was the pilots’ error and loss of spatial orientation. This was due to insufficient training of the crew, the inability to fly multi-engine aircraft and lack of knowledge of how to use the direct-display attitude indicator.
This is a known problem in aviation. The Soviet attitude indicator shows a fixed (painted) horizon line and shows how the aircraft moves relative to it. In the American attitude indicator, on the contrary, the “plane” is fixed but the horizon moves. In practice, this means that on American aircraft the instrument “horizon” is always parallel to the real horizon, but on Soviet aircraft the display is arranged completely differently. Even experienced military pilots, both Russian and American, reported this problem when they tried to fly each other’s planes in the 1990s. I had to force myself not to mix left and right shots.
The Tu-134 and An-2, on which the crews flew before, have Soviet attitude indicators, and the Boeing 737 has American attitude. Since the flight took place at night, it was possible to navigate only by instrument readings, which led to the error. Additionally, the airline’s planes were poorly maintained and the crew suffered from overwork. Finally, the forensic examination revealed that the level of ethyl alcohol in Medvedev’s body exceeded the norm for a healthy body. Doctors suggest that alcohol may have formed in the body due to natural processes after death, so it is impossible to make a definitive conclusion about the pilot’s drunkenness.
There was indeed confusion in the communication between the controller and the aircraft, but a qualified pilot in a serviceable aircraft should not have sent it to the ground even if there was no communication.
The Investigative Committee of the Prosecutor’s Office placed the main responsibility for the tragedy on Rodion Medvedev and opened a criminal case, but soon dropped the case due to the death of the suspect.