What happened
On June 5, 197el, a Standard Cirrus glider, registration HB-1269, was participating in a regional competition flight launched from Birrfeld airfield. After releasing from a tow at 900 meters, the pilot climbed to approximately 1200 meters while searching for thermals near the Gisliflue. Finding no rising air, the pilot attempted to return to Birrfeld but encountered unexpected, heavy descending air currents.
Believing the aircraft could still reach a known landing field near Brunegg, the pilot continued the flight despite insufficient altitude. As the aircraft reached approximately 100 meters above the ground near Möriken, it became clear that the intended field was unreachable. The pilot attempted a landing on a nearby meadow, executing a 130-degree left turn with the intention of maneuvering toward the original target via subsequent turns. During this maneuver, the left inner wing struck a 380-volt overhead power line. The impact caused the aircraft to enter a spin, eventually crashing tail-first into a private garden.
The investigation
The investigation examined the pilot's flight decisions, the meteorological conditions, and the mechanical state of the aircraft. The pilot held a valid glider license and showed no signs of health impairment at the time of the accident. The Standard Cirrus was airworthy, with no pre-existing technical defects identified, and the weight and balance were within legal limits.
Investigators analyzed the wind conditions, noting a Bise (northeast) wind at the surface. The investigation also reviewed aviation regulations regarding the necessity of circling a landing site to check for obstacles and the responsibility to avoid negligent flight maneuvers that endanger third parties.
Findings
- The pilot failed to account for the significant downdrafts expected in the lee of the Chestenberg mountain due to the prevailing Bise wind.
- There was a lack of decisive action, as the pilot delayed the decision to perform an outlanding despite having sufficient altitude to reach alternative suitable sites earlier.
- The landing was attempted at an altitude that was far too low to allow for a proper assessment of obstacles or to reach the intended landing field.
- The collision with the power line was the direct result of the low-altitude maneuvering and the failure to identify hazards in the landing path.