What happened
On Saturday, April 14, 1984, a private pilot departed from Wangen-Lachen airfield in a Cessna F 152, registration HB-CNL, for a local training flight. The planned itinerary involved approximately three-quarters of an hour of flying in the Amden-Ricken-Wangen area. After takeoff, the pilot performed four touch-and-go circuits before heading south.
Around 11:00 local time, skiers observed the aircraft approaching the Pizol massif (2,844 m) from the west. The pilot turned northward south of the summit and descended over the Pizol glacier, disappearing behind the Wildseeluggen toward the Pizol ski area southwest of Bad Ragaz.
Shortly thereafter, witnesses located 500 meters west of the Pizol Hut reported hearing a small aircraft engine approaching from the east. They watched the plane descend into the narrow Valplona valley. One witness noted the aircraft leveled off and then banked sharply to the left over its port wing. Another observer, sunbathing nearby, saw the plane execute a slow, glider-like left turn before suddenly dropping to its left side.
The Cessna impacted a snow-covered southern slope in the Valplona valley, approximately 60 meters below the ridge crest, at an altitude of 2,160 m. The aircraft was destroyed upon impact. The pilot, the sole occupant, sustained fatal injuries and died at the scene. No third-party property damage occurred.
The investigation
SUST investigators examined the wreckage, which lay nose-up in the snow with the empennage broken off but the fuselage geometry largely intact. Deformation patterns indicated a near-vertical impact. The flaps were found retracted, fuel tanks contained significant fuel, and the engine was at full power upon impact, suggesting the propeller struck loose snow while generating maximum thrust.
Medical examination confirmed the pilot died from trauma consistent with the crash; he had no alcohol or medication in his system. He held a valid private pilot license issued in 1973, with 214 total flight hours, 132 of which were in the Cessna F 152. However, he had not flown in the preceding three months.
Weather conditions were excellent: clear skies, windless, visibility over 20 km, and a temperature of +2°C. A reconstruction flight demonstrated that the pilot likely attempted to cross a snow ridge bounding the valley to the north. The investigation could not determine definitively whether the stall occurred while approaching the ridge or during an attempt to turn around.
Findings
The accident was caused by the aircraft entering a stall due to flying below minimum lift speed. Contributing factors included inadequate mountain flying tactics, specifically entering a terrain canyon (Valplona valley) without sufficient altitude reserve for recovery. The pilot flew into a confined area at an altitude that did not allow for a safe turnaround, leading to the loss of control near the ridge.
Safety action
No specific safety recommendations or actions were recorded in this source report beyond the identification of the causal factors.