What happened
On the evening of August 20, 2016, an Alexander Schleicher Rhönlerche II, registration HB-969, was conducting a passenger flight as part of the Wittinsburg flying days at the Wittinsburg airfield. The flight was operated under visual flight rules (VFR) following a winch launch.
During the approach, the aircraft reached a height of approximately 120 m AGL before initiating a right-hand turn for the final approach to runway 28. At an altitude of roughly 80 m AGL, rainfall intensified, causing visibility through the cockpit canopy to deteriorate significantly. Consequently, the pilot lost all visual reference to the runway during the final segment of the approach.
The left wing of the sailplane struck a cornfield located ahead of the runway threshold. This impact caused the aircraft to rotate approximately 90 degrees left around its vertical axis while still airborne. The aircraft subsequently touched down sideways, just meters from the runway markings, and slid across the grass runway, continuing to rotate until it came to a halt near the runway centerline.
The investigation
The investigation focused on the environmental conditions and the pilot's ability to maintain visual references during the landing phase. Investigators examined the weather conditions at the time of the incident, noting overcast skies, a low cloud base of approximately 150 m AGL, and light drizzle that transitioned into heavier rain.
Findings
- The primary cause of the accident was that the pilot underestimated the impact of rainfall on visibility through the cockpit canopy.
- The intensification of rain during the final turn led to a total loss of visual runway references.
- The impact with the cornfield resulted in light injuries to one passenger and significant damage to the aircraft, including a broken landing skid, torn fuselage fairing, compression of the left wing root and spar, and a torn lower wing skin.