An-24 crash in Bugulma

The An-24 crash in Bugulma was an aviation accident that occurred early on the morning of Tuesday, 26 November 1991, near Bugulma Airport. An An-24RV airliner of the airline Tatarstan Airlines was completing a domestic passenger flight on the route Nizhnevartovsk — Tyumen — Bugulma, but during the landing approach at Bugulma Airport the airliner abandoned the approach and went around. While climbing for the go-around it abruptly entered a steep dive and crashed to the ground on the airport grounds, being completely destroyed. All 41 people on board were killed — 37 passengers and 4 crew members.

This was the last aviation accident in the USSR.

Chronology of events

An-24RV registration CCCP-47823 was operating a charter flight from Nizhnevartovsk to Bugulma with an intermediate stop in Tyumen, carrying a shift of oil workers. According to the meteorological forecast passed to the crew, a westerly wind of 9 m/s with gusts of 15 m/s, stratus and cumulonimbus clouds at a height of 120—300 metres, fog, horizontal visibility of 800 metres and vertical visibility of 80 metres were expected at Bugulma. The crew was also warned about severe icing in cloud and precipitation.

The flight to Bugulma passed without significant remarks, and on approaching the airport the crew, after receiving clearance, began to descend. However, in violation of the flight manual and forgetting the warning, the crew did not at first switch on the anti-icing system (POS). Only at a height of 1100 metres was the anti-icing of the inlet guide vanes and air intakes switched on. Then, at a height of 900 metres, the icing warning was triggered, but the crew did not switch on the wing and tail anti-icing.

On the controller's instructions the approach was flown on a landing heading of 192° using the RSP+OSP system, and at this stage the co-pilot was flying the aircraft. 11 kilometres from the airport, at a height of 400 metres, the crew intercepted the glide path and requested landing clearance. The controller gave them this clearance and also passed on the actual weather, but did not mention the possibility of icing. Having received landing clearance, the crew extended the flaps to 15° at a height of 400 metres. Next, the flight engineer should have inspected the surface of the stabiliser, but he did not do so and did not see that it was becoming covered in ice. Then, approaching the glide path entry, the crew further extended the flaps to the landing position (30°), thereby violating the flight manual's procedures for operation in icing conditions and with the anti-icing system switched off.

The airliner approached the outer marker 45 metres above the glide path, but the controller did not warn the pilots about this and did not instruct them to abandon the landing and go around. When 3500 metres remained to the runway threshold, the crew, at a constant speed of 220 km/h, brought the aircraft into the zone of permissible deviations in heading and height. However, 2600 metres from the runway threshold the pitch trim balance was disturbed, as the elevator, because of icing, began to deflect more and more. Also, 1700 metres from the runway the airliner began to drift to the right, and 1400 metres from the runway it went beyond the permissible limits, while descending at a vertical speed of 7 m/s.

Crash

Seeing such a significant lateral deviation, at 05:01:26 the controller instructed the crew to go around. In the cockpit itself the decision height alert then sounded, after which, 5 seconds later, the captain instructed the co-pilot, who was flying the aircraft, to go around. He pulled the control column towards himself, and the engine power was increased to takeoff power, after which the aircraft, having descended to a height of 60 metres, began to transition into a climb; however, the flaps remained in the landing position, as a result of which the horizontal tail found itself at supercritical negative angles of attack. The control column began spontaneously to move "away" (nose-down), and the belated actions of the co-pilot or his abrupt handling led to the iced-up elevator deflecting fully downwards, which in turn led to the nose dropping and the aircraft entering a steep dive. A negative load factor arose, and recovering the aircraft from such a dive requires considerable force. However, the low height and the resulting shortage of time deprived the pilots of the possibility of saving the situation.

At 05:02:00, at a speed of 260 km/h and a dive angle of 70—80°, the An-24 struck the ground 802 metres beyond the runway threshold and 598 metres to the right of its centreline, after which it was completely destroyed. There was no fire, but all 4 crew members and 37 passengers on board were killed.