What happened
On March 24, 2011, a Schweizer 300C helicopter departed from the Halbenrain landing site for a private flight toward Lanzen/Turnau. The pilot, accompanied by two passengers, intended to land at an off-airport site at the Pogusch pass height in Sankt Marein, Styria.
During the approach, the pilot encountered significant meteorological challenges. A strong west wind created lee-side effects, including downdors and sudden tailwinds, which severely impacted the aircraft's performance. Despite maintaining full engine and rotor RPM and maximum collective pitch, the pilot was unable to maintain altitude due to the rising terrain and the wind-induced loss of lift.
Unable to reach the intended landing site, the pilot attempted an emergency landing on a roadside verge near the L123 highway. The maneuver was unsuccessful; the helicopter likely experienced an increase in lift due to ground effect after initial contact, causing it to move backward. The aircraft subsequently struck a fence with its skids, slid across a meadow, and overturned on its right side. The impact resulted in three light injuries (the pilot and two passengers) and the total destruction of the aircraft.
The investigation
The SUB investigation focused on the pilot's experience, the meteorological conditions, and the legality of the flight plan. Investigators examined the pilot's training records, which showed a relatively low total flight time of approximately 57 hours, with only 18 hours as Pilot-in-Command (PIC). The investigation also analyzed the aircraft's performance capabilities relative to the terrain and wind conditions present at the time of the accident.
Findings
- The pilot lacked the necessary experience and maturity to manage the complexities of an off-airport landing in mountainous terrain.
- The flight was unauthorized, as the pilot did not possess the required permit for landing at the Pogusch site.
- Lee-side wind effects and downdrafts caused by the west wind significantly reduced the helicopter's effective performance during the approach.
- The approach altitude was insufficient for the rising terrain, likely dropping below the required 150m AGL.
- The pilot's low level of flight experience contributed to an inability to properly assess and plan for the environmental challenges encountered.