Sequence of events
At 18:05 (17:05 MSK) at Babushera Airport in Sukhumi, flight SU-974 Sukhumi—Moscow was preparing for takeoff. It was operated by a Tu-134A aircraft, tail number CCCP-65836, with 82 people on board (6 crew members and 76 passengers). Having taxied via taxiway No. 3 to the holding point, at 18:05:35, Flight 974 was cleared to enter the takeoff position (at the beginning of the runway) on a magnetic heading of 297°. At 18:07:50, the Tu-134 crew reported ready for takeoff.
At the same time, flight G-73 Sukhumi—Kutaisi was preparing for takeoff at Babushera Airport. It was operated by a Let L-410M aircraft, tail number CCCP-67191, with 11 people on board (2 crew members and 9 passengers). Flight 073 was scheduled to depart at 17:50, and the crew was in a hurry. At 18:06:45, the L-410 crew contacted the taxi controller and at 18:07:18 received permission to taxi via taxiway No. 3 to the holding point on a magnetic course of 297°, following the Tu-134. However, at 18:07:24, the captain of flight 073 independently switched to the circuit controller and requested clearance for takeoff on a course of 117°, in the opposite direction. The circuit controller coordinated this with the flight director and approach controller, then gave a vague response: "Go ahead and calculate." Interpreting this phrase as clearance, the crew of flight G-73 began taxiing. Violating several instructions, as well as the controller's directions, they decided to proceed to the start position via the shortest route: through the link between the apron and the old runway, and then along the old runway to its intersection with the new runway.
At 18:07:42, the captain of Flight 073 again contacted the taxi controller and requested permission to taxi to the holding point to take off on course 117°. Without waiting for confirmation, he transmitted: "On the link 117 taking position." The taxi controller, who had previously issued the correct instructions for the L-410 to taxi to the start position via taxiway No. 3, now simply dismissed flight 073 and did not take any measures to prevent these unauthorized taxiing actions according to the non-existent scheme.
At 18:08, flight SU-974 began takeoff. Simultaneously, at 18:08:08, the captain of flight G-73 requested permission from the taxi controller to switch to the start control point (SCP) frequency, while omitting that he was at the holding point. Unaware of the true situation, the taxi controller granted this permission. At 18:08:22, the captain of flight 073 reported to the SCP: "On the holding via the link, 191st." Due to engine noise from the departing flight 974, the start controller did not hear the report properly and at 18:08:30 asked for clarification: "Which aircraft?" The L-410 crew, without stopping at the holding point, replied: "191st, holding… ready," then, without clearance, unauthorizedly moved onto the runway at the intersection of the old and new runways, 1,650 meters from the start of the runway. The captain of Flight 073 then repeatedly requested permission to take up the takeoff position. The start controller could not see the actual position of both aircraft from his workstation and, without understanding the situation, in violation of air traffic control requirements, instructed flight G-73 to take up the takeoff position and prepare for takeoff on a course of 297°: "191st, 297 take up, wind 270 four." By this time, the L-410 had already been on the runway for several seconds and was turning to take off on course 117°.
The Tu-134 had been accelerating for 26 seconds, reaching a speed of 195 km/h when its crew suddenly saw the L-410 on the runway 400 meters ahead. To avoid a collision, the crew of Flight 974 immediately decided to abort the takeoff and move to the left on the side safety strip; the aircraft's spoilers, thrust reversers, and braking were immediately activated. The L-410 crew also saw the departing Tu-134, so they immediately set the engines to takeoff mode and attempted to move to the right, but the aircraft did not have enough time to avoid each other. After 33.5 seconds of acceleration, at a speed of 216 km/h and 1,626 meters from the runway threshold, Flight 974's right wing collided with flight G-73, then veered onto the left safety strip and stopped 514 meters from the collision site and 2,140 meters from the runway threshold, 48 meters to the left of its axis.
There was no fire at the crash site, but the damage was very severe. The Tu-134's right wing cut off the left wing of the L-410 and sliced through the entire fuselage along the level of the windows; the cockpit detached, rotated 180°, and fell onto the runway, and both propellers were torn off and thrown 50 meters away. All on board flight 073—both pilots and 9 passengers (8 adults and 1 child)—died instantly. The Tu-134 suffered damage to the leading edge of the right wing, and the fuselage was corrugated in the area of frames 41–45. None of the 82 people on board were killed, but due to the sustained damage, the airliner was written off on September 16, 1982.
Investigation
The investigation concluded with the following findings:
- The captain of the L-410 did not comply with the taxi controller's instructions regarding the taxi procedure to the holding point, independently changed the taxi route, grossly violated the requirements of the NPP GA-78 and IPP Sukhumi Airport, independently switched to the circuit controller in violation of radio communication rules, and unauthorizedly entered the runway ahead of a departing aircraft.
- The taxi controller did not prohibit taxiing on an unestablished route.
- The start controller cleared the L-410 crew to take up the takeoff position while the Tu-134 was taking off and the L-410 was already on the runway.
- The circuit controller, in violation of the established radio communication phraseology, allowed the crew to take off on course 117°. This information contributed to the L-410 crew violating the taxiing scheme.
- The flight director did not coordinate the shift's work, did not control the actions of the controllers, and did not ensure compliance with the IPP Sukhumi Airport requirements.
It was also found that the L-410 captain had previously taxied in violation of the scheme with the permission of the taxi controller. Earlier that day, while operating a local flight from Sukhumi Airport, he taxied onto the runway via the same route.
Thus the causes of the accident at Sukhumi Airport were the unauthorized occupation of the runway by the crew of the L-410M aircraft during the takeoff of the Tu-134A aircraft, inadequate organization of flight management at Sukhumi Airport, gross violations of the NPP GA-78, NSD GA-81, Instructions for flight operations in the aerodrome area, and the technology of work by the flight director, traffic controllers, and the L-410M crew.
