What happened
On July 19, 1969, at approximately 17:34, a student pilot was conducting a solo aero-tow flight at Birrfeld airfield. The flight involved performing three right-hand spirals followed by a left-hand circuit. While approaching runway 26, the pilot executed a 180-degree turn into a left base leg and briefly deployed the airbrake flaps.
During the final approach, the pilot maintained a speed of approximately 80 km/h and initiated a leftward sideslip. While focused on maintaining the correct direction and preparing for landing, the pilot was unable to correct a directional deviation despite using the rudder. After leveling the aircraft out of the sideslip, the pilot failed to retract the airbrake flaps. Consequently, the pilot realized the aircraft was on a collision course with trees located roughly 200 meters before the start of the runway. Fearing a wing strike if a lateral maneuver was attempted, the pilot maintained the flight path, leading the Rhönlerche II, registration HB-576, to strike the treetops. The impact caused the aircraft to spin 180 degrees to the left before hitting the ground. The pilot sustained no injuries, though the aircraft suffered significant damage, including a severed left wing section.
The investigation
The investigation was based on written reports provided by the student pilot and the flight instructor. The inquiry examined the pilot's training history, the aircraft's technical condition, and the environmental factors at the time of the accident. The investigation confirmed that the aircraft's weight and center of gravity were within limits and that the pilot held a valid student pilot license.
Findings
- The primary cause of the accident was a low approach.
- The pilot's concentration was diverted by the difficulty of maintaining the correct heading during the sideslip.
- The failure to retract the airbrake flaps after exiting the sideslip contributed to the loss of altitude.
- Significant sun glare was present, as the sun was positioned at an azimuth of 274 degrees, very close to the aircraft's approach heading of 260 degrees, which may have impacted visibility through the canopy.