Accident Overview
On the evening of 20 August 2016, a Rhönlerche II glider with registration HB-969 was involved in a landing accident at the Wittinsburg airfield in Basel-Landschaft, Switzerland. The aircraft was operated by the Segelfluggruppe Basel Fricktal and was conducting a passenger flight as part of the Wittinsburger Flugtage airshow. The pilot held a valid sailplane pilot license (SPL) issued by the Federal Office of Civil Aviation (BAZL) and had accumulated 1,372 total flight hours, with 24 hours and 7 minutes on the accident aircraft type.
Sequence of Events
The glider launched via winch on runway 28 under overcast skies with a cloud base of approximately 150 m AGL and light drizzle. After reaching a release height of about 120 m AGL, the pilot immediately entered a right crosswind leg for the same runway. During the final turn at roughly 80 m AGL, rain intensified, and visibility through the canopy decreased. The pilot reported losing all visual reference to the runway in the final part of the approach. Subsequently, the glider's left wing struck a maize field in front of the runway. The aircraft then rotated about 90 degrees to the left in the air before touching down with its landing skid perpendicular to the runway direction, just a few meters before the runway markings. It slid across the grass runway, continuing to rotate, and came to rest nearly aligned with runway 28.
Aircraft and Pilot Information
The glider, an Alexander Schleicher Rhönlerche II (HB-969), sustained light damage: the landing skid broke, fuselage fairing tore, left wing bow and wing root were compressed, and the lower wing covering was torn. No third-party damage occurred. The pilot, a Swiss citizen born in 1963, had flown 33 hours and 42 minutes in the last 90 days, including 4 hours and 19 minutes on the accident type. The passenger was not injured.
Investigation Conclusion
The investigation concluded that the pilot underestimated the influence of rain on visibility through the canopy, which led to the loss of visual reference to the runway and subsequent collision with the maize field before the runway threshold.