What happened
On September 1, 2016, at approximately 17:45 local time, a Piper PA-28-161, registration S5-DES, crashed in a cold valley beneath Krasji vrh, near Bovec Airport (LJBO). The aircraft, a four-seat single-engine piston plane, was operating under Visual Flight Rules (VFR) for a private flight. The pilot was accompanied by two passengers.
The flight departed Bovec with the intention of returning to the home base at Ljubljana (LJLJ). After takeoff from runway 25, the aircraft performed a right turn and continued southeast at an altitude of approximately 200 meters, flying between the Javoršček and Polovnik hills. During the flight, the pilot deviated from the previously planned departure route. While navigating the narrowing valley, the aircraft attempted a 180-degree right turn. This maneuver resulted in a loss of airspeed, leading to a stall and a subsequent steep dive into the terrain. The impact resulted in the destruction of the aircraft and one fatality among the crew, while the two passengers sustained serious injuries.
The investigation
The investigation examined the aircraft's technical condition, the pilot's medical and flight history, meteorological conditions, and the operational procedures at Bovec Airport. Investigators analyzed GPS data and flight tracks to reconstruct the vertical and horizontal profile of the flight. The investigation also reviewed the regulatory oversight provided by the Civil Aviation Authority (CAA) regarding the airport's operational manual and safety standards for departures in mountainous terrain.
Findings
- The pilot held valid licenses and medical certificates, and the aircraft was properly maintained with no mechanical failures identified in the engine, propeller, or control systems.
- Meteorological conditions, including an approaching weather front, likely pressured the pilot to alter the planned route to shorten the return flight.
- The airport operator did not enforce consistent safety criteria for departures, specifically regarding minimum safety altitudes for engine aircraft, due to insufficient oversight by the CAA.
- The pilot's psychophysical readiness was likely compromised by fatigue, time pressure, and the presence of alcohol.
- The primary cause of the accident was the loss of control during a maneuver resulting in an aerodynamic stall.
Safety action
Following the initial findings, the investigation service issued a safety recommendation to the CAA to review and strengthen the instructions and criteria for minimum safety standards for arrivals and departures at Bovec Airport.