On 18 May at 03:02 Moscow time the flight departed from Irkutsk Airport, proceeding en route to Chita at an altitude of 9,000 metres (30,000 ft).

Five eyewitnesses reported seeing and hearing an explosion in the air at between 09:35 and 09:45 local time (03:35 to 03:45 Moscow time); according to the commission responsible for the investigation, the aircraft broke up mid-air into several sections consistent with a sharp sudden change in pressure.

Forensic investigation revealed that the explosion was caused by passenger Chingis Yunusogly Rzayev, born in Irkutsk in 1941.

[5] When he tried to infiltrate the cockpit the policeman Vladimir Yezhikov shot him in the back; the bullet hit the area of the 8th intercostal space before it penetrated the heart.

As Rzayev laid dying, he managed to activate the bomb he had with him, consisting of 5.5–6 kilograms (12–13 lb) of TNT.The final report stated "The cause of the airplane crash, which broke apart in mid-air killing all passengers and crew, was the explosion of a bomb by a terrorist who tried to force the crew to change the course of the aircraft."