What happened
On August 28, 2018, at 14:10 local time, an An-2 aircraft, registration LZ-1409, was performing aerial application of liquid fertilizer over a sunflower field near Brusartsi, Montana Province. During the eleventh flight of the day, the crew became distracted by a flock of birds perched on a high-voltage power line. While attempting to maneuver around the birds, the crew failed to notice a 20 kV electrical wire on a converging course. In a last-second attempt to fly beneath the wire, the aircraft struck the lower conductor, severing it.
The impact caused significant damage to the aircraft's tail section, including a 93 cm section of the vertical stabilizer and damage to the vertical rudder. The aircraft also lost a portion of its radio antenna. Following the strike, the crew performed an emergency landing in an adjacent field. There were no injuries to the two crew members.
The investigation
The investigation examined the flight history, aircraft maintenance records, and the crew's actions during the encounter. Investigators reviewed the aircraft's technical logs, confirming that the An-2 and its engine were within their required service intervals. The investigation also analyzed the meteorological conditions and the operational procedures of the operator, "DI EM VI 2010" EOOD. The inquiry focused on the crew's decision-making process when encountering obstacles and the adherence to established flight altitude minimums.
Findings
- The crew's attention was diverted by a flock of birds on a high-voltage line.
- The crew failed to maintain the required flight altitude of 50 meters above obstacles, as specified in the operator's Standard Operating Procedures (SOP).
- The collision with the 20 kV power line was the primary cause of the incident.
- The aircraft sustained structural damage to the vertical stabilizer, rudder, and antenna due to the impact.
- The operator's safety program lacked a documented list of identified risk factors.
Safety action
Following the incident, the operator conducted a training session for all aviation personnel regarding aerial application instructions and operating manuals, specifically focusing on handling complex terrain. The investigation recommended that the operator test the crew's knowledge of SOPs and implement a formal risk factor list within their safety management program.