What happened
On October 21, 2016, two cargo and passenger transport flights were scheduled by LLC RN-Vankor using Mi-8T helicopters operated by Skol Airlines. The flights were intended to depart from Urengoy for destinations including Vankor and Suzun, with a planned refueling stop at the R-40 settlement. The initial flight plans for flight SD9370, involving aircraft RA-25326, and flight SD9375, involving aircraft RA-22869, were set for departures at 03:30 and 03:40, respectively.
However, meteorological conditions at Urengoy and along the intended flight paths were unsuitable for Visual Flight Rules (VFR). Early morning observations at the Urengoy weather station indicated significant low-level stratus clouds at altitudes of only 90 meters and a horizontal visibility of 5 km. Although conditions began to improve after 06:00, with cloud bases rising to 150 meters, the forecast for the flight area indicated continued low visibility in certain low-lying areas. Due to these unfavorable weather conditions, the scheduled departures were delayed until 07:00. To manage the delay, the pilot of flight SD9375 coordinated with the pilot of flight SD9370 to perform both scheduled missions sequentially using both available helicopters.