Flight Plans and Weather Conditions
On October 21, 2016, according to requests from RN-Vankor LLC, passenger and cargo transportation was planned using Mi-8T helicopters operated by SKOL Airlines from Urengoy airfield to the Vankor and Suzun landing sites, with intermediate landings at the R-40 landing site for refueling. Flight plans filed on October 20 by the airline's dispatch service scheduled flight SD9370 (Urengoy–Vankor) on Mi-8T RA-25326 at 03:30, and flight SD9375 (Urengoy–Suzun) on Mi-8T RA-22869 at 03:40.
Due to meteorological conditions at Urengoy and along the route not meeting visual flight rules (VFR) minima, departures were delayed until 07:00. Weather observations at the Urengoy AMSG from 02:10 showed significant (5–7 oktas) low stratiform clouds at 90 m with a horizontal visibility of 5 km. By 06:00, cloud cover decreased to 3–4 oktas and the base rose to 150 m. The GAMET forecast amendment for areas 1–7 of the Tarko-Sale FIR, valid from 06:30 to 12:00, predicted visibility of 4000 m (locally 2000 m in low areas) and significant cloud at 150 m (locally significant at 100 m in low areas for areas 1, 6, and 7).
Crew Coordination and Decision
The captain assigned to flight SD9375 agreed with the captain of flight SD9370 to alternate both flights on Mi-8T helicopters RA-25326 and RA-22869. At 06:40, the captain received a weather briefing at the Urengoy AMSG for the forecast areas along the route to Vankor and made the decision to depart. According to the flight plan, flight SD9370 was to follow the route: Urengoy airfield – Pionernaya landing site – R-40 landing site – Vankor landing site – R-40 – Pionernaya – Urengoy.
No further events were reported in the source.