Collision en vol entre Ka 4 Rhönlerche II et SZD-22B au-dessus d'Oberwald, Suisse
Le 30 juillet 1964, une collision en vol s'est produite entre un Alexander Schleicher Ka 4 Rhönlerche II et un SZD SZD-22B près d'Oberwald, en Suisse. L'incident s'est produit lors d'un camp d'entraînement de vol à voile organisé par le Groupe de vol académique de Zurich. La collision a entraîné le crash du Ka 4 Rhönlerche II, causant la mort de son pilote, tandis que le pilote du SZD-22B a réussi à sauter en parachute pour se mettre en sécurité, mais a subi de graves blessures. L'enquête a attribué la collision à une surveillance inadéquate de l'espace aérien par les deux pilotes.
- Aerotow — thermaling: After aerotow release over the Oberwalder Blasen ridge, the Rhönlerche II HB-573 began soaring in local lift as part of a training flight with altitude and area limits set by the instructor.
- Low-time student pilot: The HB-573 was flown solo by a relatively inexperienced student pilot with about 11 hours total time, operating in alpine terrain under training constraints.
- Instrument-focused flying: Both pilots were likely concentrating on variometer, airspeed, and slip indication to optimize weak lift and minimize sink, reducing continuous outside visual scanning.
- Shared lift area: HB-573 and HB-659 were both operating in the same lift area several hundred meters from the Oberwalder Blasen slope, with at least one witness indicating they were circling one above the other, possibly in opposite directions.
- Inadequate lookout: Neither pilot maintained sufficient all-round airspace surveillance to detect the other glider in time to adjust circling direction or take effective avoiding action.
- Frontal wing collision: The two gliders collided frontally with the leading edges of their left wings striking each other at about mid-span, causing structural failure of both left wings.
- Crash - fatal: HB-573 immediately entered a steep spin and crashed on the slope, killing the pilot, while HB-659 broke up and its pilot bailed out with serious injuries.