Ka 6 crash near Hausen am Albis after turbulence encounter
On June 9, 1964, an Alexander Schleicher Ka 6 BR glider crashed near Hausen am Albis, Switzerland. The pilot, a 39-year-old male, was conducting a cross-country flight when the glider encountered turbulence near the Albiskette ridge. The aircraft experienced a loss of speed and altitude, resulting in a crash from approximately 30 meters. The pilot sustained serious injuries, including fractures, but there were no fatalities. The glider was significantly damaged, with repair costs estimated between 70% to 80% of its value.
- Cross-country soaring: After launching by aerotow from Hausen am Albis at 1230, the pilot continued a cross-country soaring flight in the local area when the expected weather did not materialize.
- Low ridge clearance: On the return leg from Sihlbrugg, the pilot flew along the Albiskamm with only about 50 m clearance above the ridge, providing little height margin in case of sink or turbulence.
- Lee-side turbulence: The glider crossed from the windward to the lee side of the Albis ridge into an area of moderate Bise-induced lee turbulence behind tall trees.
- Airspeed misjudged: With a tailwind in the lee, the pilot likely judged his speed by groundspeed and believed he was flying at a normal speed, although true airspeed was probably too low.
- Turn initiated low: Realizing too late that his height was insufficient to continue, the pilot initiated a relatively abrupt turn in the turbulent lee flow at low altitude.
- Stall and nose drop: The combination of low true airspeed, turbulence, and abrupt control input led to an aerodynamic stall with the glider losing speed and pitching nose-down from about 30–40 m AGL.
- Crash - serious injury: From insufficient height to recover, the glider impacted the ground almost straight ahead in a forest clearing, heavily damaging the aircraft and seriously injuring the pilot.