Background
On 15 January 2015, the helicopter commander received instructions from his employer, OOO "Kustard," to transport passengers to the Kosh-Agach District of the Altai Republic on 20 January 2015, for the purpose of wolf hunting. The flight was to be conducted under visual flight rules (VFR) in Class G airspace over mountainous terrain.
Flight Preparations
The commander filed a flight plan through the appropriate channels, with the route: Kuzedeyevo – Kosh-Agach – then along coordinates near the Mongolian border – Kosh-Agach. Approval for the flight and the border zone was obtained from the border service. Weather information for the flight area was retrieved via the internet.
Flight to Kosh-Agach
On 20 January 2015, at 02:10, the commander conducted a preflight inspection of the helicopter. At 02:45, he departed from Kuzedeyevo with two passengers onboard. The flight was uneventful, and at 04:10, he landed on an unprepared site on the outskirts of Kosh-Agach. The remaining fuel after the flight was 40 liters.
Refueling and Departure
At the landing site, the commander refueled the helicopter with 160 liters of TS-1 fuel from a tanker belonging to AU RA "Avialesookhrana," bringing the total fuel to 200 liters (the full tank capacity is 280 liters). To prevent water crystallization, an additive labeled "IM" was added in a quantity recommended for the ambient temperature. The takeoff mass was 1071 kg, which did not exceed the R-66 flight manual maximum of 1225 kg, and the center of gravity was 2390 mm, within the limits of 2310–2540 mm. At 05:20, the commander took off with three passengers for a general aviation flight. According to the commander's explanation, at 05:40... (the source text ends here).