What happened
On July 19, 1987, a German national piloting a Cessna 210 (registration D-EEZO) departed from Herzogenaurach Airfield in West Germany with his wife as a passenger. Their destination was Lugano, Switzerland. Prior to departure, the pilot obtained a weather briefing in Nuremberg at 08:35 local time. The meteorological officer warned that parts of the Alps were already obscured by clouds and that conditions would deteriorate throughout the day due to cumulus formation. Specifically, the cloud base south of the Alps was expected to be between 3,000 and 4,000 feet. Despite these warnings, the pilot filed a VFR flight plan and departed at approximately 10:40.
The aircraft followed a route via radio beacons at Dinkelsbühl, Villingen, Trasadingen, and Brunnen. The pilot maintained regular contact with air traffic control, reporting his position at various points. His last transmission occurred around 12:08 near Brunnen, where he reported being at flight level 95 and heading directly for Lugano. At 12:13, radar contact was lost approximately 9 nautical miles south of Brunnen at flight level 96.
Search efforts were hampered by poor weather conditions. The wreckage was not located until August 20, 1987, when a helicopter crew discovered the aircraft crashed into the western ridge of Mount Krönten, roughly 5 meters below the summit. Both occupants were killed instantly upon impact.
The investigation
The Swiss Transportation Safety Investigation Board (STSB) examined the flight history, weather data, and pilot qualifications. Records indicated that the pilot was accustomed to flying this route with his wife but lacked the specific license or training required for instrument flight rules (IFR). Despite knowing the limitations of his certification, he had previously flown in IMC without authorization.
Weather reports from the accident site confirmed marginal VFR conditions with cloud bases at 2,000–2,400 meters and visibility reduced to 3–5 km in precipitation. The forecast had explicitly warned of deteriorating conditions due to convective cloud development.
Findings
The investigation determined that the primary cause of the accident was the continuation of a VFR flight into IMC. The pilot failed to maintain visual reference with the ground and terrain, leading to controlled flight into terrain (CFIT). Contributing factors included:
- Lack of Instrument Rating: The pilot did not hold the necessary license or training to fly in instrument meteorological conditions.
- Weather Misjudgment: Despite receiving clear warnings about cloud bases and deteriorating conditions, the pilot proceeded under VFR into airspace where visual reference was impossible.
- Operational Pressure: The pilot’s familiarity with the route may have contributed to a false sense of security regarding the changing weather patterns.
Safety action
This case underscores the critical importance of adhering to instrument ratings and weather minimums. It highlights the dangers of overconfidence in familiar routes and the necessity of respecting meteorological warnings, particularly in mountainous terrain where cloud bases can drop rapidly.