Ka 4 Rhönlerche II collision with trees during landing at Birrfeld airfield
On July 19, 1969, a Ka 4 Rhönlerche II experienced a collision with trees during a landing approach at Birrfeld Airfield in Switzerland. The student pilot, conducting a solo training flight, approached runway 26 too low and was unable to avoid trees located near the runway threshold. Despite the collision, the pilot remained uninjured, though the aircraft sustained significant damage. The investigation confirmed that the accident resulted from a low approach path.
- Aerotow landing approach: During a solo training flight after aerotow, the student began the landing circuit to runway 26 at Birrfeld.
- Low final approach: On final for runway 26, the student allowed the approach path to become too low relative to trees located about 200 m before the runway threshold.
- Glissade with airbrakes: To lose height from an initially high position, the pilot flew a left sideslip (glissade) with airbrakes extended and then failed to retract them after ending the glissade, increasing sink rate.
- Sun glare on final: The low sun almost directly ahead on the 260° approach, combined with a scratched canopy, likely caused significant glare and impaired the pilot’s visual assessment of the approach path.
- Fixated on aiming point: The pilot focused on maintaining direction and achieving a spot landing, became somewhat tense when unable to correct a heading deviation in the glissade, and did not adequately monitor height over the trees.
- No effective avoidance: After finally noticing he was aimed at the trees, the pilot chose not to turn or markedly increase speed, instead hoping to clear the obstacle, and likely left the airbrakes extended.
- Crash - no injury: The glider struck the tops of two trees short of runway 26, rotated about 180° and impacted the ground, substantially damaging the aircraft but leaving the pilot uninjured.