Background
According to the official accident investigation report, the incident involved a helicopter operating under the flight manual (RPP) of IP Karanova M.I. The flight was intended for aerial survey work. The commander was required to make the takeoff decision after briefing with the customer and assessing actual weather and lighting conditions.
Weather Conditions
The weather forecast for the Khabarovsk FIR (Area 16, where the accident occurred) predicted a cloud base of 900 meters above sea level and mountain obscuration. The maximum terrain elevation within a 2-kilometer strip along the planned route from Olenya Gorka to Peak Chekhov was 1050 meters. According to section 7.1 of the operator's RPP, for daytime aerial surveys over mountains up to 2000 meters, the weather minima require a cloud base no lower than 400 meters above ground and visibility of at least 2000 meters. The forecast conditions at the destination (Peak Chekhov) did not meet these VFR minima or the RPP requirements.
Decision
The report states that it was not possible to determine whether the commander had information about the actual and forecast weather at the time of the takeoff decision. Nonetheless, the commander's decision to take off was considered unjustified. After preparing the helicopter with the assistance of a maintenance technician and maneuvering it out of the hangar, two passengers arrived at Olenya Gorka. The commander boarded them, and at 03:59 requested clearance from the Sakhalin ATC tower to start the engine.
Conclusion
The investigation concluded that the takeoff decision was made without proper justification given the adverse weather forecast.