Investigation Summary
The flight was plagued by irregularities from the start, carrying 47 passengers in a 32-seat cabin, which included 13 illegal boarders. During the flight, the crew requested and received shortcuts that took them away from established air corridors. As they approached Makhachkala, the crew falsely reported being on the correct corridor, while the approach dispatcher, despite seeing the aircraft off-course on radar, failed to correct them. Instead, the dispatcher authorized a descent to 1,800 meters in a sector where the terrain reached heights of nearly 900 meters. The situation worsened when the landing dispatcher provided two consecutive incorrect bearing reports, leading the crew to believe they were closer to the airport and the landing course than they actually were. Relying on these erroneous ATC instructions rather than their own navigation instruments, the crew descended to 400 meters while still in the mountains. The Yak-40, which was not equipped with a Ground Proximity Warning System (GPWS), struck the slope of Mount Kukurtbash at an altitude of 550 meters while the crew was attempting to break through the cloud layer to transition to visual flight.
Final Conclusions
The investigation concluded the accident was caused by gross violations of flight rules and ATC regulations in mountainous terrain. Key factors included the unauthorized off-course flight, the failure of ATC to provide accurate position data, and the crew's decision to descend below safe altitudes without positive confirmation of their location. The lack of a GPWS and the crew's false reporting of their position also contributed to the disaster.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Navigation Instruments
The crew failed to utilize available onboard navigation instruments to verify their position, relying instead on erroneous ATC reports.
Ground Proximity Warning System (GPWS)
The aircraft lacked this system, which would have provided an automated alert as the plane approached the mountain slope.
ATC Radar
The aircraft entered a 'blind' zone where mountain peaks obscured the radar return, leading the dispatcher to guess the aircraft's position.
Interesting Facts
- 01The aircraft was configured for 32 seats but carried 47 passengers, including 13 unauthorized individuals.
- 02The aircraft was not equipped with a Ground Proximity Warning System (GPWS).
- 03The landing dispatcher provided two consecutive incorrect bearing reports to the crew.
- 04The crew falsely reported passing the outer marker when they were actually 23 kilometers away from the airport.
- 05The aircraft struck the slope of Mount Kukurtbash at an altitude of 550 meters; the mountain's peak elevation is 894 meters.
Safety Actions & Advisories
ATC Procedural Adherence
The investigation highlighted the critical need for ATC to maintain aircraft on established air corridors in mountainous terrain and to provide accurate radar position data.