Summary
On 18 June 1999, a Piper PA-28-161, registration HB-PPA, crashed at the north flank of Rossberg (Türlistock) in Switzerland. The aircraft was destroyed by impact and subsequent fire. The sole occupant, the pilot, was fatally injured.
Flight History
The flight departed from Kägiswil with the intention of reaching St. Gallen-Altenrhein for a business appointment. The pilot had filed a flight plan indicating his return by 1300 LT the next day. After takeoff, the pilot established radio contact with Alpnach tower and Buochs between 0920 and 0931 LT, then contacted Zurich FIC reporting position "Küssnacht" and a planned route via Zug and Pfäffikon. No further radio contact was recorded after 0933 LT. Witnesses observed a white small aircraft flying low and with an irregular flight path between 0945 and 1000 LT near Morgartenberg toward Ober- and Unterägeri. The aircraft then collided with trees on the north slope of Rossberg while flying parallel to the terrain. The right wing remained lodged in the trees, and the rest of the aircraft struck the ground east of the trees, catching fire.
Aircraft and Pilot
The aircraft was a 1992 Piper PA-28-161, a four-seat low-wing monoplane powered by a Textron Lycoming O-320-D3G engine. It was privately owned and had no known technical defects. The pilot, a Swiss national born in 1971, held a private pilot license that had expired on 24 May 1999. His total flight experience was approximately 111 hours, all on the accident type. In 1998 he logged no flight hours; in 1999 he had flown 1 hour 54 minutes and 4 landings during a refresher flight with an instructor, who assessed his skills as above average. No passengers were on board.
Weather Conditions
According to the Swiss Meteorological Institute, weather at the accident site at the time included 4-7/8 stratocumulus with a base of 3500-4500 ft and 7-8/8 stratocumulus with a base of 6000-7000 ft, with weak to moderate rain and showers. Visibility outside clouds was about 5 km. Wind was from 320° at 5-10 knots with gusts to 15 knots. The temperature was 11°C with a dewpoint of 10°C; QNH was 1020 hPa. Lightning strokes were registered in the Alpstein region. Witnesses at Alpnach tower reported high fog, haze, and fine rain with visibility of 4-6 km. A military pilot flying a helicopter from Dübendorf to Alpnach reported poor visibility east of Lake Zug with precipitation and low cloud base. A private pilot who attempted a similar route from Hausen am Albis to St. Gallen-Altenrhein reported a cloud base between 1000 and 1500 m AMSL and variable visibility, locally 2-3 km near hills, and aborting his flight due to weather. Ground witnesses described the weather as thundery and rainy with poor visibility.
Wreckage and Fire
Examination of the wreckage revealed that the engine and propeller were rotating up to the moment of impact. The right wing was separated from the fuselage due to tree contact and showed no soot or fire damage. The cockpit and most of the fuselage were completely burned, likely due to fuel from the left wing tank. No evidence of arson or pre-impact fire was found. The avionics and instruments were too damaged to reconstruct readings.
Medical Findings
Autopsy at the University of Zurich Institute of Forensic Medicine found no foreign substances or carbon monoxide in the pilot's system, indicating no impairment from drugs, alcohol, or fire before impact. The impact was determined to be unsurvivable.
Probable Cause
The accident was caused by the continuation of a visual flight in poor visibility conditions, resulting in collision with trees and terrain. Contributing factors included the pilot's low flight experience and low recent training, and the possibility that his business appointment adversely influenced his decision to abort the flight or land at an alternate aerodrome.