Collision en vol entre Karpf Baby et Grunau Baby au-dessus de Weiningen lors d'un vol d'entraînement

Le 12 avril 1961, une collision en vol s'est produite entre un Karpf-Flugzeugbau Karpf Baby et un Edmund Schneider Grunau Baby près de Weiningen, en Suisse. Les deux planeurs participaient à des vols d'entraînement dans le cadre d'un camp de vol à voile organisé par le Segelfluggruppe Winterthur. La collision s'est produite à environ 750 mètres d'altitude alors que les deux planeurs exploitaient la même zone de thermiques. Le pilote du Karpf Baby a réussi à se sauver en parachute, mais le pilote du Grunau Baby a été mortellement blessé. L'enquête officielle a attribué la collision principalement à une surveillance insuffisante de l'espace aérien par le pilote du Grunau Baby.

1. Aerotow — thermaling: After an aerotow launch at 12:58 and release around 13:02, the HB-497 pilot began thermaling and rapidly gaining height in the established lift area north of Frauenfeld.
2. Shared thermal use: HB-497 entered and circled in the same thermal column where HB-512 was already circling above with the same left-hand turn direction, creating vertical proximity in the same air mass.
3. Limited experience & workload: As a relatively low-time student pilot performing a required thermaling task, the HB-497 pilot was likely highly focused on climbing performance and instrument indications, increasing susceptibility to neglecting lookout.
4. Inadequate lookout above: While climbing in the thermal, the HB-497 pilot began or continued circling without adequately monitoring the airspace above, failing to detect the higher HB-512 despite converging vertically.
5. Continued climb under HB-512: HB-497 continued to climb in the same left-hand circle beneath HB-512, with the vertical separation steadily decreasing as observed by a witness, and with the HB-512 pilot no longer keeping HB-497 continuously in sight.
6. Converging flight paths: As HB-497 rose and HB-512, likely slipping outward and no longer climbing, both gliders’ circular paths converged laterally and vertically until HB-497’s right wing leading edge appeared just below HB-512’s right wing, leaving no time to avoid impact.
7. Crash - fatal: HB-497’s forward fuselage struck the trailing edge of HB-512’s right wing, tearing it off; HB-512 entered an uncontrolled descent from which the pilot bailed out safely, while the severely damaged HB-497 went into a steep dive and crashed, fatally injuring its pilot.