What happened
On September 27, 2012, an An-2, registration RA-33601, was scheduled for a multi-leg cargo and passenger flight originating in Surgut and traveling through Saranpaul and Arbynya before reaching Ivdel. Prior to the initial departure, an aircraft technician refueled the aircraft with approximately 1,200 liters of fuel. While the technician verified the fuel level via the filler neck strainers, the total quantity was not verified using the aircraft's fuel gauge. Additionally, the pilot did not undergo the required pre-flight medical examination at the Surgut airport.
On September 28, 2012, the pilot operated the first leg from Surgut to Saranpaul alone, landing at 14:00. The pilot reported having 580 liters of fuel remaining upon arrival, and no refueling took place at Saranpaul.
On September 29, 2012, at 01:43, the aircraft departed Saranpaul for the next leg toward Arbynya and Ivdel, carrying four passengers. The aircraft landed at Arbynya at 03:16, with the pilot reporting a remaining fuel level of 250 liters. Following a 24-minute ground interval, the aircraft departed Arbynya at 03:40, heading for Ivdel, which was 164 km away. Approximately 60 km into this flight, a warning light indicated a critical low fuel level in the right wing.