An-12 crash near Batagay

The An-12 crash near Batagay was an aviation accident that occurred on Tuesday, 4 October 1988. An An-12B military transport aircraft of the airline Aeroflot was operating cargo flight SU-40066 on the Tiksi—Batagay—Yakutsk route, but during the approach to Batagay, due to errors by the pilots and the air traffic controller, it crashed into a mountain 25 kilometres from Batagay airport. All 6 crew members on board were killed.

Chronology of events

An-12B aircraft USSR-11418 was operating flight SU-40066 from Tiksi to Yakutsk with an intermediate landing in Batagay; on board were 6 crew members and 15,495 kilograms of cargo (apples). On 4 October 1988 the aircraft was flying the first leg of the route (Tiksi—Batagay). Flight SU-40066 took off from Tiksi at 20:50 MSK+6.

The weather forecast at Batagay airport from 13:00 to 22:00 predicted a storm, surface wind 200°, 7 m/s with gusts up to 12 m/s, visibility more than 10 kilometres, cloud cover 10 oktas stratocumulus, cumulonimbus at 1000 metres, tops at 4000 metres, mountains partially obscured. At 22:31 the crew reported entering the Batagay air traffic control (ATC) area at an altitude of 6300 metres. At 22:40 the crew, on the air traffic controller's instruction and without carrying out pre-landing preparation, began the descent and immediately began an approach on a magnetic heading of 225° using a procedure designed for a visual approach.

At 22:44 the trainee commander, together with the crew, carried out the pre-landing preparation; at the same time (on the instruction of the instructor commander) the sequence of actions for an approach using a non-existent procedure was determined in advance, about which the pilots did not inform the air traffic controller. At 22:50, 38 kilometres from the runway and on entering the airport area, the crew reported to the air traffic controller that they had reached an altitude of 3800 metres and were planning an approach using the beacons of the reverse direction. The air traffic controller, guided by insufficiently clear wording of the Batagay airport flight operations instructions, which led to an ambiguous interpretation, cleared the crew to descend to 3000 metres for an instrument approach on a magnetic heading of 225°, although this procedure was intended only for a visual approach. While the aircraft was descending towards the outer locator beacon (DPRM), the controller, in violation of the requirements, did not monitor the flight using the direction finder and did not give the pilots bearings; at the same time, continuous radar monitoring of flight 40066 on this procedure was impossible due to a non-optimal choice of the antenna tilt angle of the Batagay airport radar.

The short distance from Batagay airport (according to the requirements the distance should have been 45 kilometres) at the moment the crew decided to violate the descent and approach procedure, and the aircraft's high altitude (5000 metres), predetermined that flight SU-40066's descent and approach to Batagay airport would be carried out at maximum forward and vertical speeds. The descent from 5000 metres to 4500 metres was carried out at a vertical speed of 8.5 m/s with the aircraft's speed increasing to 445 km/h; subsequently the vertical rate of descent increased to 12.5 m/s. At an altitude of 3000 metres the aircraft stopped descending and was put into level flight, and at 22:55:03 (6 kilometres before the DPRM, at a speed of 360 km/h and with a bank of 15-20°) the crew began the third turn in violation of the established procedure, misinforming the air traffic controller with a report of passing the DPRM. The air traffic controller did not check the accuracy of the report by the pilots of flight 40066 and did not determine the actual position of the aircraft, and at 22:55:07 cleared the crew for further descent to an altitude of 1200 metres and an approach with a left turn according to the procedure, which was done in violation of the requirements (the requirements stipulated that an approach in mountainous terrain using the established procedure was permitted only with continuous radar monitoring).

At 22:57 there was a change of air traffic controllers at the control tower (KDP). At 22:57:14 the pilots of flight 40066 reported to the new air traffic controller that they had reached an altitude of 1200 metres. The air traffic controller gave the pilots the transition level and the airport pressure and cleared a descent to an altitude of 500 metres. The crew confirmed setting the airport pressure and continued descending to an altitude of 500 metres. When the crew reported, the air traffic controller did not monitor flight 40066 using the direction finder, did not pass a bearing to the crew, did not detect the violation of the approach procedure and, in violation of the requirements, cleared the crew to continue the approach. The pilots continued the descent with numerous violations of the requirements of the An-12 Flight Manual (RLE), as well as other requirements (the crew set the aerodrome pressure at the transition level of 1200 metres without putting the aircraft into level flight, did not read the checklist and continued descending at increased speeds without extending the landing gear and flaps). 58 seconds before the crash the pilots reported to the air traffic controller that they had reached an altitude of 500 metres and were beginning the fourth turn, while actually being at an altitude of 700 metres, in a right turn with a bank of 15° and an indicated airspeed of 408 km/h, and on a heading of 80°, which did not ensure a safe manoeuvre to get onto …