What happened
On the morning of April 2, 1969, a Cessna 170 A, registration HB-CMB, departed Geneva for a planned VFR flight to Altenrhein. The aircraft was carrying the pilot and two passengers. Prior to departure, the pilot consulted with the flight weather service at Geneva Airport. Despite being warned by the weather official that the cloud ceiling was only between 800 and 1000 feet and that conditions were insufficient for safe VFR flight, the pilot chose to proceed, expressing confidence in his local knowledge.
The aircraft failed to arrive at its destination. Following an extensive search operation involving aircraft and helicopters across Switzerland and Germany, the wreckage was eventually discovered on July 12, 1969, in the Plasselbschlund area near Plasselb. The impact occurred in a steep, wooded area. All three occupants of the aircraft perished in the accident, and the aircraft was destroyed.
The investigation
Investigators examined the wreckage and the flight history of the pilot. The aircraft was found in a steep descent, having struck the tops of fir trees approximately 25 meters before its final resting position. The impact was severe enough to sever both wingtips. Analysis of the engine and propeller suggested the engine was likely at idle power during the impact.
Technical records indicated that while the aircraft was airworthy, there was an outstanding report regarding a non-functional stall warning that had not yet been rectified. The investigation also reviewed the pilot's experience, noting that while he held a valid private pilot license, he had relatively limited flight hours and had been described by instructors as prone to losing situational awareness in unexpected circumstances.
Findings
- The pilot proceeded with the flight despite receiving specific warnings regarding low cloud ceilings and deteriorating weather.
- The aircraft was not equipped or certified for instrument flight (IFR), making it unsuitable for flight in the low clouds encountered.
- The pilot lacked the necessary training and experience to safely navigate the unfavorable weather conditions.
- The aircraft likely entered the cloud layer, leading to a loss of spatial orientation.
- The terrain, characterized by steep and densely wooded hills, left no viable options for an emergency landing.