Kollision in der Luft zwischen Ka 4 Rhönlerche II und Grunau Baby II nahe Siblingen, Schweiz

Am 1. April 1961 kam es zu einer Kollision in der Luft zwischen einer Alexander Schleicher Ka 4 Rhönlerche II und einem Edmund Schneider Grunau Baby II nahe Siblingen, Schweiz. Beide Segelflugzeuge flogen in Hangaufwindbedingungen, als die Rhönlerche II mit dem Grunau Baby II kollidierte, was zu erheblichen Schäden an beiden Flugzeugen führte. Trotz der Kollision konnten beide Piloten sicher und unverletzt landen. Die Untersuchung ergab, dass das Verhalten des Rhönlerche II-Piloten zur Kollision beitrug, indem er das Grunau Baby II während einer Rechtskurve aus den Augen verlor.

1. Ridge soaring flight: After aerotow launches from Schaffhausen-Neunkirch, the Rhönlerche HB-669 was ridge soaring along the Siblinger Schlossranden behind and below the Grunau Baby HB-170 in smooth hang lift.
2. Close trail position: As both gliders flew south toward the Randenturm at about 1100 m MSL, the Rhönlerche pilot allowed his aircraft to close to roughly 50 m behind and 20–30 m below the Grunau Baby, a small separation given his limited experience.
3. Right turn by lead: Near the Randenturm, the Grunau Baby, slightly left and above, initiated a right turn, contrary to the Rhönlerche pilot’s expectation of a left turn at the end of the ridge.
4. Follower mirrors turn: The Rhönlerche pilot immediately initiated a right turn as well, from a position slightly right-behind and below the Grunau Baby, and in doing so lost visual contact with the other glider.
5. Converging flight paths: While the Rhönlerche pilot had the Grunau Baby out of sight, the two gliders’ right turns caused their flight paths to converge laterally, rapidly reducing the remaining separation.
6. Late evasive maneuver: Both pilots suddenly reacquired sight of the other aircraft only moments before impact, and although the Rhönlerche pilot steepened his bank and pushed down, the collision could no longer be avoided.
7. Mid-air collision: The left wingtip of the Rhönlerche penetrated the nose of the Grunau Baby, causing serious structural damage to both gliders, but both pilots maintained control and landed safely without injury, one returning to Schaffhausen and the other outlanding near Hinterranden.