Ka 6 Absturz nahe Hausen am Albis nach Turbulenzbegegnung

Am 9. Juni 1964 stürzte ein Alexander Schleicher Ka 6 BR Segelflugzeug nahe Hausen am Albis, Schweiz, ab. Der 39-jährige Pilot führte einen Streckenflug durch, als das Segelflugzeug in der Nähe des Albiskette-Grates auf Turbulenzen traf. Das Flugzeug verlor an Geschwindigkeit und Höhe, was zu einem Absturz aus etwa 30 Metern führte. Der Pilot erlitt schwere Verletzungen, darunter Frakturen, aber es gab keine Todesopfer. Das Segelflugzeug wurde erheblich beschädigt, mit Reparaturkosten, die auf 70% bis 80% seines Wertes geschätzt wurden.

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.
7. 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.