What happened
On June 26, 2024, a pilot attempted a takeoff from the Saarmund special landing field in a SD-1 Minisport light aircraft. The aircraft taxied via taxiway C to runway 27 and began its takeoff roll at 09:02 local time. The takeoff was performed with a tailwind.
During the initial climb, the aircraft maintained a ground speed of approximately 85 km/h, which was below the recommended climb speed of 90 km/h. As the aircraft left the wind shadow of nearby buildings and trees, it encountered a steady 8-knot wind from the east. The pilot likely responded to the reduced climb performance caused by the tailwind by increasing the angle of attack. This maneuver caused the airspeed to drop toward the stall speed and increased aerodynamic drag, leading to a loss of climb capability. An eyewitness reported observing an aerodynamic stall and hearing a dull engine sound. The aircraft subsequently stalled over the left wing and crashed onto a grassy area southwest of the runway perimeter. The pilot sustained fatal injuries, and the aircraft was destroyed.
The investigation
The BFU investigation examined the aircraft's flight data, which was recovered from a navigation app on a damaged iPad. The investigation also reviewed the airfield's operational procedures, the condition of the runway, and the meteorological conditions at the time of the accident. Investigators analyzed the aircraft's weight and balance, noting that while the pilot and baggage were within limits, the aircraft was within the allowable takeoff mass. The investigation also looked into the airfield's regulatory restrictions, which had recently mandated that takeoffs only occur from runway 27 and landings from runway 09, effectively forcing tailwind operations during easterly winds.
Findings
- The primary cause of the accident was a loss of control due to an aerodynamic stall during the initial climb.
- The takeoff was performed with a significant tailwind, which was approximately 20% of the required takeoff airspeed.
- Operational restrictions at the airfield necessitated a takeoff into the wind, which resulted in the tailwind condition.
- The runway surface was uneven with tall grass (up to 30 cm), which was problematic for the aircraft's low propeller clearance.
- The pilot was not formally registered in the airfield's "flight operations without an air traffic controller" procedure on the day of the accident.