What happened
On August 1, 2020, a pilot was conducting a cross-country flight in a Discus-2b sailplane, registration HB-3281, from Saanen to Schänis. During the flight, the aircraft experienced a continuous loss of altitude while flying near the Hohgant mountain. Upon reaching the Bumbach area, the pilot identified a suitable meadow for an outlanding and decided to divert to this field because the low altitude made continuing the planned route toward Alpnach impossible.
After initially passing the field, the pilot turned back to approach the landing site. The approach was performed with a high true airspeed of approximately 125 km/t, which was significantly above the manufacturer's recommended approach speeds. Upon touchdown on the wet grass, the pilot deployed the spoilers and applied the wheel brakes, but the aircraft failed to decelerate and began to slide. In a final attempt to avoid an obstacle at the end of the field, the pilot executed a maneuver to intentionally ground the left wing to induce a turn. However, the aircraft slid sideways, causing the right wingtip to strike the wall of a wooden hut at a nearby campsite, resulting in light damage to the aircraft and a broken window in the structure.
The investigation
SUST examined the flight path, meteorological conditions, and the aircraft's performance during the landing. The investigation established that the meadow was wet due to recent rainfall in the area. The investigators also analyzed the pilot's decision-making process regarding the approach and the flight speeds used during the final stages of the landing.
Findings
- The pilot's decision to return to the field was made very late, as the aircraft was already at the edge of the decision funnel, leaving little time to plan a standard traffic pattern.
- The approach included high-bank turns of over 45 degrees, which increased operational risk.
- The excessive approach speed—roughly 30 km/h above the recommended manual limits—significantly increased the landing energy and lengthened the required rollout distance.
- The combination of high speed and the wet grass surface rendered the wheel brakes ineffective, preventing the pilot from stopping before the end of the field.