What happened
On June 17, 1973, a Jodel DR 340 aircraft, registration HB-EFV, departed Yverdon for a private flight to Lugano-Agno. The pilot was accompanied by three passengers. While the flight plan originally intended to traverse the Simplon route toward Domodossola and eventually Lugano, the aircraft entered the Veddasca Valley in the Ticino region.
As the aircraft progressed through the valley, it flew at an extremely low altitude. Witnesses near Indemini observed the plane flying low through the valley, even brushing against a cable car line. At approximately 10:54 h, while attempting a left turn near the base of Monte Tamaro, the aircraft's left wing struck a tree. The impact caused the aircraft to crash and subsequently catch fire. The accident resulted in three fatalities (the pilot and two passengers) and one serious injury to the remaining occupant. The aircraft was destroyed.
The investigation
The investigation examined the aircraft's technical condition, the pilot's experience, and the prevailing meteorological conditions. Technical analysis of the engine and propeller showed no evidence of mechanical failure prior to the collision. The aircraft's weight and center of gravity were found to be within permissible limits.
Investigators also reviewed the pilot's flight history, noting a modest total of approximately 80 flight hours, with only 14 hours experienced on this specific type. Meteorological data revealed that while forecasts had predicted good visibility, actual conditions in the southern Alps were characterized by heavy fog and significantly reduced horizontal visibility, particularly when flying toward the sun.
Findings
- The pilot committed a navigation error by mistakenly entering the Veddasca Valley instead of the intended Tresa Valley.
- Reduced visibility, much lower than forecasted, prevented the pilot from recognizing the error in a timely manner.
- The pilot's flight tactics were inadequate, as the aircraft was flying at an insufficient altitude for the terrain and visibility conditions.
- A lack of foresight in flight planning and execution contributed to the inability to safely execute a turnaround once the error was realized.