Incident Overview
On July 4, 2016, at 15:18 local time, a private pilot flying an AS202/15-1 aircraft (registration HB-HFW) from Salzburg Airport (LOWS) to Innsbruck Airport (LOWI) experienced an engine malfunction during the approach. The aircraft was operating under visual flight rules (VFR) in a private capacity.
Sequence of Events
Shortly before reaching waypoint MIKE 3, the engine began running rough. The pilot activated the booster pump and decided to execute a precautionary landing to avoid overflying populated areas. He informed Innsbruck tower of his decision. During the approach to a field selected for landing, the engine failed completely. The aircraft touched down on the field, and the pilot and two passengers remained uninjured. The aircraft sustained no damage.
Investigation Findings
The investigation was delegated to the Swiss Safety Investigation Board (SUST) by the Austrian authority. Interviews with the pilot revealed that the flight from Salzburg to Innsbruck was planned to take 65 minutes, with an additional 60 minutes of fuel reserve. However, strong headwinds significantly prolonged the flight. The pilot had previously flown another aircraft of the same type with different fuel gauge characteristics, leading him to believe more fuel was available than actually present. The fuel gauges in older aircraft are often unreliable and do not allow precise assessment of fuel quantity. In this case, the pilot relied primarily on these gauges, resulting in fuel exhaustion before reaching an airport.
Conclusion
The decision to perform a precautionary landing upon the first sign of engine malfunction was safety-conscious, especially since activating the booster pump had no effect. As the aircraft had no reported defects, the investigation was concluded as a summary investigation in accordance with Art. 45 and Art. 46 of the Swiss Ordinance on Safety Investigations.