Kollision in der Luft zwischen Ka 4 und Piper J3C-65 am Flughafen Sion

Am 26. August 1966 ereignete sich am Flughafen Sion eine Kollision in der Luft zwischen einer Piper J3C-65 und einer Alexander Schleicher Ka 4 Rhönlerche II. Der Vorfall ereignete sich, als die Ka 4, gesteuert von einem Schüler, nach einem erfolglosen Flug zur Landung zurückkehrte. Gleichzeitig bereitete sich die Piper mit einem Fluglehrer und einem Schüler an Bord auf den Start vor. Die Flugzeuge kollidierten etwa 15 bis 20 Meter über der Startbahn, was zur Zerstörung beider führte. Der Fluglehrer und ein Schüler wurden tödlich verletzt, während der andere Schüler schwere Verletzungen erlitt.

1. Aerotow — local soaring: In late afternoon the student in Greif I HB-579 launched on aerotow from Sion for a planned duration flight but was unable to find sufficient lift and eventually returned toward the airfield to land.
2. Mixed traffic operations: At Sion the grass runway 26 was being used simultaneously by gliders and powered aircraft under a complex mixed-traffic arrangement where glider circuits could intersect powered aircraft approaches and departures.
3. Piper preparing departure: While the glider was returning to land, the instructor took the front seat of Piper J-3C HB-OAV after his student’s previous flight and taxied to the threshold of the grass runway 26 to depart again with the student on board.
4. Piper initiates takeoff: The instructor in HB-OAV commenced a takeoff run on the grass runway 26 at the same time that glider HB-579 was on short final to land, placing both aircraft on converging, vertically overlapping flight paths.
5. Priority not yielded: Contrary to rules giving landing aircraft and gliders priority, the Piper instructor continued the takeoff instead of holding clear of the approach path of the landing glider.
6. Converging flight paths: The glider on final and the Piper climbing after liftoff reached the same area about 400 m beyond the runway 26 grass threshold at roughly 15–20 m above ground with insufficient separation to avoid each other.
7. Mid-air collision: The glider HB-579 and Piper HB-OAV collided about 15–20 m above the grass runway 26 at Sion, then crashed between the two parallel runways, destroying both aircraft and causing serious injuries to all three occupants, two of whom later died.