[2][3] The aircraft involved in the accident was a Tupolev Tu-104B, registered СССР-42405 to the West Siberia Civil Aviation Directorate, a division of Aeroflot.

At 08:33:45 local time, when the flight was just seven kilometres (4.3 mi; 3.8 nmi) from the runway, the air traffic controller warned that they were close to missing the glide slope.

In reality, the aircraft's speed was around 270–275 km/h (146–148 kn; 168–171 mph), causing a left bank and a lateral deviation of 30 metres (98 ft).

[1] Due to flying 25–30 km/h (13–16 kn; 16–19 mph) less than the recommended speed, the aircraft reached a critical angle of attack.

The instruments most likely gave inaccurate readings, causing the crew to reduce speed before touching the runway led to a hard landing.

While simulating the flight to determine the cause of the erroneous indications, the depressurization happened approximately three minutes after turning off the cabin pressurization.

The investigation cited the three primary causes of the accident as follows: The lack of objective airspeed reading available to the crew on approach due to mechanical errors upon depressurization of the cabin when reaching a low altitude.Flying at too slow a speed at a dangerous rate of climb, 25–35 km/h (13–19 kn; 16–22 mph) below the recommended parameters, which, with insufficient forward speed, led to the impossibility of performing a normal leveling and a rough blow to the runway surface, exceeding the design load and destroying the aircraft.

The erroneous actions by the crew were flying at too slow a speed while landing in difficult conditions with not enough time or altitude to solve the issue.