What happened
On February 1, 1965, a flight student was conducting a required 300-kilometer triangular navigation flight for his private pilot certification. The flight sequence began on the previous day, January 31, when the student departed Olten for Prangins/La-Côte. Although the airfield manager at Prangins had advised against the flight due to poor visibility and snow, the student proceeded and eventually stayed overnight in Prangins due to deteriorating weather.
On the morning of the accident, the student departed Prangins at 09:00, landing in Bern at 09:56. After receiving permission from his flight instructor to continue the flight toward Olten, the student departed Bern at 10:18. During the flight, the aircraft encountered a cold front moving through the region. Near Wynau, the aircraft entered an area of dense fog where visibility was reduced to just 20 meters above the ground. Witnesses observed the Piper J3C Cub, registration HB-OVA, flying erratically at low altitude along the Aare river and the main road. At 10:51, the aircraft suddenly pitched to the left and entered a steep dive, crashing 40 meters from the main road. The pilot was killed, and the aircraft was destroyed.
The investigation
Investigators examined the flight history, weather reports, and the pilot's qualifications. The investigation established that the student had approximately 46 hours of flight experience. Meteorological data showed that a cold front had passed through the region, significantly reducing visibility and bringing rain. The investigation also reviewed the communications between the student and his flight instructor, noting that while the instructor provided specific routing instructions to avoid the Jura mountains, he did not personally verify the broader weather conditions or ensure the student had sought proper meteorological briefings.
Findings
- The immediate cause of the crash was a loss of airspeed at an altitude too low to allow for recovery. This was likely caused by the pilot reducing speed due to poor visibility and focusing more on terrain avoidance than maintaining proper flight attitude.
- The pilot flew into weather conditions that were no longer suitable for visual flight rules (VFR).
- The flight instructor authorized a navigation flight under unsuitable weather conditions and failed to verify if the student had obtained an adequate weather briefing.
- The student failed to seek proper weather information from official sources in Zurich or Geneva, which would have revealed the deteriorating conditions.