Flight Plan and Preparation
On December 7, 2017, the pilot-in-command of a Eurocopter AS 350B3, registration RA-07277, planned a flight with one passenger from Bratsk (landing site near Gidrostroitel microdistrict) to the settlement of Chistiy in the Bratsk District of Irkutsk Oblast, and back. The flight was conducted for general aviation purposes. The pilot submitted a flight plan to the Novosibirsk Air Traffic Management Center on December 6, 2017. The intended route passed through airspace classes C and G.
It could not be determined whether the pilot analyzed the meteorological conditions along the route. The pilot did not request a pre-flight weather briefing from the Bratsk weather station. Around 11:00 local time, the pilot arrived at the Gidrostroitel landing site, refueled the helicopter, and performed pre-flight inspection, as confirmed by security camera footage. A pre-flight medical examination was not conducted, which was permitted under the applicable regulations (FAP-128, clause 8.10.1).
Departure and Communication
At 12:37 local time, after takeoff from Gidrostroitel, the pilot established contact with the Bratsk Approach controller. While proceeding along the Bratsk–Chistiy route, at 12:42, the pilot switched to the Bratsk Area control frequency, reported passing the 30 km boundary, and stated that the flight to Chistiy was being conducted at an altitude of 350 meters (QNH). The area controller approved the flight at that altitude and instructed the pilot to establish the next radio contact no later than 15:45 local time.
Loss of Contact
The pilot's last radio transmission occurred at 12:44, during which he requested the closure of his flight plan at 05:00 UTC. This transmission was unrelated to any emergency. At 13:18, the passenger made a call via mobile phone. No further communications were received from the helicopter.