Introduction
On Saturday, 10 March 1979, a Piper J3C aircraft, registration HB-OEM, was involved in an accident at Ruezenwil near Bernhardzell, Switzerland. The flight was conducted under visual flight rules (VFR) from Altenrhein to Sitterdorf. The aircraft was operated by Flugbetriebs AG Sitterdorf.
Accident Sequence
The flight instructor and a student pilot departed Altenrhein at approximately 1835 local time. The intended route was to Sitterdorf. Due to rapidly deteriorating visibility caused by advancing twilight and meteorological conditions, the pilot lost spatial orientation. He attempted a forced landing on a meadow. During the maneuver, the aircraft fell from a low height and crashed at about 1850 local time.
Both occupants sustained serious injuries. The aircraft was destroyed, and minor ground damage occurred to the meadow.
Aircraft and Occupants
The aircraft was a Piper J3C, built in 1944, with a Continental C90 14F engine producing 66 kW (90 HP). The total airframe hours at the time of the accident were 2770:45. The aircraft had a maximum allowable takeoff weight of 580 kg, but the actual weight at the time of the accident was approximately 605 kg; the center of gravity remained within limits. Fuel on board was about 60 liters at departure, with an estimated 47 liters remaining at the time of the accident, providing about 2 hours and 8 minutes of flight time.
The flight instructor, born 1940, held a professional pilot license and a flight instructor license, with a total of 1621:11 hours on motor aircraft, including at least 500 hours on the accident type. The student pilot, born 1945, had a learner's permit and 29:59 hours of motor flight experience, all on the Piper J3C.
Weather Conditions
According to the Swiss Meteorological Institute, weather at the accident site was characterized by rapid deterioration from the west due to an active warm front, with precipitation including snow. Cloud cover was 8/8 with bases around 1500 m above sea level, lowering to 1100 m and locally to 800 m. Visibility was 5-10 km, reducing to 2-5 km in precipitation, and locally lower. Wind was from 210 degrees at about 5 knots. Sunset occurred at 1819 local time, with the official night boundary at 1853 local time; however, due to thick cloud cover, darkness fell earlier.
Witnesses near the accident site reported gusty west wind, snowfall, and visibility of non-illuminated objects less than 100 m. Darkness was well advanced.
Cause
The accident was caused by an unsuccessful forced landing after the pilot lost orientation due to weather-induced early darkness. A contributing factor was the failure to plan sufficient daylight reserve at departure.