Flight History
On 24 July 1993 at approximately 1845 local time, a Cessna RA 152 (registration HB-CGO) crashed at Lachenalp in the canton of Glarus, Switzerland. The aircraft was operated by Fliegerschule Birrfeld on a private sightseeing flight. The pilot, accompanied by his ten-year-old daughter, had departed Birrfeld at 1735. The planned route included the Säntis, Buchs, Walensee, and the Glarus region. The pilot intended to cross the Lachengrat ridge (approximately 6000 ft) to reach the Klöntal valley. Witnesses reported the aircraft was flying at about 5500 ft in a slow climb with normal engine sounds in the upper Oberseetal valley.
Shortly before the Lachengrat, the pilot realized he was too low to clear the ridge and that a turn was no longer possible. The airspeed had dropped to 45 knots. The aircraft then stalled and struck the terrain, coming to rest inverted in a rocky stream bed. The cabin remained intact, suspended between the banks. A small fuel fire ignited but extinguished itself. The pilot lost consciousness initially; his daughter was able to exit the wreckage unassisted. After regaining consciousness, the pilot and his daughter walked to an alpine hut where they received help. The pilot sustained serious injuries, his daughter minor injuries. The aircraft was destroyed.
Investigation Findings
The investigation determined that the weather at the time was ideal, with visibility over 10 km, no turbulence, and light variable winds. The aircraft was properly maintained and within weight and balance limits. The engine was producing high power at impact, as evidenced by propeller marks. The pilot held a valid private pilot license with 193 total flight hours, including 75 on type. He had flown only 6 hours in the previous 90 days. His flying training was described as having been interrupted for several years, and a 1991 requalification attempt on another model was abandoned due to difficulties. The flight instructor later assessed the pilot as uncertain, slow to recognize situations, and lacking coordination.
Examination of the wreckage indicated the mixture control was in the full-rich position, which according to the flight manual would have reduced climb performance above 3000 ft. However, the investigation noted that leaning the mixture would likely not have prevented the accident. The pilot's reported altitude of 7500 ft upon entering the Oberseetal was inconsistent with the actual flight path; the investigation concluded the initial altitude was insufficient to clear the ridge.
Cause
The accident was attributed to incorrect mountain flying tactics and continuing flight in an ascending mountain valley without the possibility to turn back.