What happened
On October 1, 1994, a Piper Cherokee Archer I with registration HB-OQW departed from Lommis airfield in Switzerland. The pilot initially intended to fly toward the Flüelapass and Julierpass but altered the route due to weather conditions, eventually heading toward the Arlberg pass and Bregenz. After crossing the Swiss-Austrian border and flying over the Säntis region at 9,000 feet, the aircraft descended toward Degersheim and the hamlet of Nassen.
While approaching the area, the pilot initiated an unscheduled emergency landing practice maneuver over a flat ridge approximately 1.5 kilometers northeast of Nassen. Witnesses observed the aircraft descend to roughly 30 meters (98 feet) above ground level, fly over a barn roof, and then turn nearly perpendicular toward a high-voltage power line. The pilot attempted to pull up to avoid the obstacle, but the aircraft struck the line at an altitude of approximately 9 meters. A 43-meter section of the conductor became entangled with the fuselage. Despite the collision, the pilot maintained control, continued the flight to Lommis, and landed normally without injury. The incident resulted in significant damage to the aircraft and caused a power outage lasting five hours.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the flight data, witness statements, and the pilot's account. The pilot was found to be properly licensed with sufficient experience and in good health. The aircraft was airworthy, correctly maintained, and within weight and balance limits. Weather conditions were favorable, with light haze, 5 km visibility, and variable winds of 3 knots. The power line was clearly visible against the background terrain.
Findings
The investigation determined that the accident was caused by two primary factors: the pilot's failure to maintain the legal minimum flight altitude and the execution of an unnecessary in-flight maneuver.
Swiss regulations prohibit private pilots from flying below 150 meters above ground level unless accompanied by a flight instructor or a qualified pilot. The pilot had no operational need for an emergency landing practice at that time and location. He admitted to descending lower than intended without a clear explanation, only noticing the power line shortly before impact. Although he knew the area well, the maneuver was discretionary and not required by any emergency.
Safety action
The report highlights the strict regulatory requirement regarding minimum altitude for private pilots. No specific new safety recommendations were issued beyond the standard findings that emphasize adherence to flight rules and the necessity of having qualified supervision when practicing low-altitude maneuvers.