What happened
On July 31, 1976, a Piper PA 28-140 Cherokee, registration G-AXTN, was conducting a multi-leg flight from Southend, United Kingdom, to Nice, France, with stops planned for Troyes and Sion. The flight was operated by two British pilots accompanied by two passengers. After successfully reaching Troyes, the crew decided to proceed toward Sion, opting not to visit the meteorological office for updated information.
While navigating the route between Dijon and St. Prex, the crew requested an increase in altitude from 3,000 to 4,500 feet. As the aircraft approached the Jura Mountains near Lac de Joux, the pilots encountered deteriorating weather. Although they could see the ground intermittently, the terrain began to rise rapidly into the cloud base. While attempting to climb to avoid the rising terrain, the aircraft struck a ridge approximately 100 meters below the summit of Mont-Tendre. The impact destroyed the aircraft, though the pilots and passengers survived, with the two passengers sustaining grievous injuries.
The investigation
Investigators examined the flight planning, the meteorological conditions, and the pilots' experience levels. The investigation established that the crew was using a 1:500,000 scale RAF chart which clearly indicated the highest peaks in the area, including Mont-Tendre at 5,520 feet. However, the flight plan only specified a flight level of 55 (5,500 feet), and the pilots had requested an altitude of only 4,500 feet.
Technical inspections of the G-AXTN revealed no mechanical failures; the aircraft was airworthy, with sufficient fuel and oil, and within weight and balance limits. Meteorological data from Geneva indicated a cloud base of 4,000 feet, while reports from La Dole indicated zero visibility due to fog. The investigation also noted that while one pilot held an IMC qualification, the crew continued to operate under VFR rules despite the encroaching clouds.
Findings
- The flight was not prepared with the necessary attention to detail, specifically regarding the identification of the highest terrain along the route.
- The pilots failed to recognize that the terrain peaks, such as Mont-Tendre, exceeded their intended flight altitude.
- The crew demonstrated a lack of foresight by continuing a VFR flight into unfavorable meteorological conditions.
- Insufficient pilot experience and training regarding mountain flying and the specific performance capabilities of the aircraft contributed to the accident.
- The pilots' decision to climb into a cloud layer rather than descending to maintain visual contact with the ground led to the controlled flight into terrain.