chronology of events
23:48. The crew of flight SU821 conducted a pre-flight medical check-up in Moscow and obtained clearance to fly. The aircraft commander was 34-year-old Rodion Medvedev, with roughly four thousand total flight hours, more than a thousand on this type. He was assisted by 43-year-old Rustem Allaberdin as co-pilot, whose overall flight time approached nine thousand hours, yet he had logged only about 276 hours on this model.
23:55. Medvedev assessed the aircraft’s condition, weather data, payload, and aviation information before deciding to proceed with the flight.
23:59. One passenger texted a friend before engine start, expressing fear, noting that the commander’s voice sounded as if he were intoxicated.
01:13. Aeroflot Nord Boeing 737 departed from Moscow for Perm. On board were two pilots, 82 passengers, and four flight attendants. Among the passengers were 61 Russian citizens, many Azerbaijanis and Ukrainians, and several Western Europeans. Also onboard was Gennady Troshev, a prominent general from the Chechen conflicts, who led the combined Russian forces.
01:40. The climb proceeded without incident, reaching about 9100 meters. The flight appeared stable during ascent.
02:45. As the aircraft neared Perm, a descent was initiated. The crew prepared for landing according to the MH 4A procedure and aimed for runway 21 with a 212° approach path.
02:46. The Perm airport controller instructed the aircraft to follow long-range beacon code 705 PX as the initial approach point, guiding the plane toward Boris, the radio name for the MH 4A approach path. The controller framed the landing procedure as MH 4B, with the radio pronunciation of B resembling Boris.
02:50. The crew faced confusion when the dispatcher redirected them to a longer, more complex route. It later emerged that the change was meant to accommodate Lufthansa’s Airbus A319 en route to Frankfurt.
02:51. The crew asked for the route details after hearing the dispatcher’s explanation. The dispatcher responded, claiming they were heading toward the drive, a phrase that could be interpreted in two ways and effectively canceled the MH 4B approach. The pilots rechecked the MH 4A model for a time.
02:52. A sequence of chaotic yet technically permissible maneuvers followed, with the crew descending under their own control without a clear flight plan.
02:53. The pilots questioned which route would allow the aircraft to enter the runway. They followed the dispatcher’s vaguely stated instruction, which dismissed the MH 4B plan. No explicit request for clarification was made.
02:54. The dialogue became muddled: “2-1-2 approach ready when command given for third,” said one pilot. “Understood, follow 2700 for now, route driving,” replied the dispatcher. The two parties appeared to misconstrue each other’s meaning.
02:56. The on-board computer recorded an error in location greater than 4.5 kilometers. This could reflect a natural inertial navigation disengagement or a fault setting before takeoff.
02:57. Medvedev and Allaberdin argued over the direction to turn. The commander favored the left, the co-pilot the right. The controller, tracking the aircraft on radar, prompted a right turn, but did not specify a landing route, leading to further disagreement.
02:58. The autopilot unexpectedly steered left due to an obstacle in the planned route, prompting confusion in the cockpit as Allaberdin asked where the aircraft had gone.
02:59. Automatic thrust control was deactivated after several conditions were met, and pilots began manual engine management. A thrust discrepancy emerged between the engines, yet the crew did not compensate with rudder input or engine balance adjustments. Instead, they attempted to stabilize the aircraft through banked roll.
03:01. The pilots commenced deceleration with spoilers while the landing gear remained undeployed and wings largely not extended. The autopilot signaled an error, provoking the commander to search for the control to disable it.
03:03. The controller expressed confusion about the aircraft’s altitude. The commander asked for guidance on descent depth, and as the situation intensified, the crew grew increasingly tense.
03:03. The pilots attempted to explain autopilot functions, with the co-pilot noting that some modes did not control altitude. The commander clarified that LVL CHG controlled descent while another mode governed the horizontal path.
03:06. Thrust asymmetry caused a roll of 32° to the left. The co-pilot interrupted autopilot with manual leveling while Medvedev demanded near-maximum engine thrust.
03:07. The aircraft gained altitude due to increased speed, and Allaberdin eventually disengaged the autopilot. Flight parameters drifted as the crew struggled to maintain control.
03:07. The dispatcher reported the altitude had risen to 900 meters and, realizing the current trajectory could not lead to a safe landing, instructed a return and a reattempt at the approach.
03:08. Medvedev abruptly turned the aircraft with a sharp bank to the right, triggering a BANK ANGLE warning. The co-pilot cried out in fear as the crew attempted to stabilize the plane.
03:08. While the dispatcher pressed for another approach, the crew did not execute it and continued discussions, prompting the dispatcher to inquire about the crew’s wellbeing.
03:09. In the final minute, the aircraft slowly rolled left and then right as the co-pilot urged the commander to take decisive action. Miscommunication and conflicting commands persisted. The thrust and bank angle indicators warned of escalating instability. The commander finally took control, but the aircraft veered, rolled dramatically, and descended rapidly. Screams filled the cabin as the plane spiraled toward disaster.
All aboard perished.
Caused?
Investigative findings attributed the disaster to pilot error and spatial disorientation, exacerbated by insufficient training, the inability to operate a multi-engine jet, and unfamiliarity with the direct-display attitude indicator. This indicator, different in design across systems, can mislead pilots who are trained on international models. The Soviet display tends to fix the horizon while the American style keeps the horizon fixed, potentially causing confusion when pilots fly unfamiliar equipment. Reports indicate that even experienced pilots from different sides observed this mismatch when testing each other’s aircraft in the 1990s, highlighting the risk of misinterpretation.
The Tu-134 and An-2 used previously by the crews employ Soviet attitude indicators, while the Boeing 737 uses an American-style system. Night operations demanded instrument-based navigation, which amplified the risk of error. Additional factors included poor aircraft maintenance, crew fatigue, and, according to forensic analyses, ethanol traces in Medvedev’s body beyond typical limits. While alcohol may have contributed to the incident, investigators cautioned that post-mortem processes can affect results, making definitive conclusions elusive (IAC report).
Communication gaps between the controller and the aircraft did exist, but a competent crew in a functioning aircraft should not have committed to a ground landing under those conditions. The Investigative Committee’s early assessment placed primary responsibility on Rodion Medvedev and opened a criminal case, though charges were later dropped following the suspect’s death (IAC report).