Accident
A twin-engine aircraft crashed in a wooded area approximately 15 km from Donaueschingen-Villingen Airport while returning from a local calibration mission. The aircraft had departed the airport in the afternoon and conducted several circuits at 7,000 feet, calibrating NDB and DME systems. The crew was approaching runway 36 in marginal weather conditions when they failed to recognize insufficient altitude, struck trees, and crashed. The aircraft was destroyed, and all four occupants were killed.
Approach and Descent
According to published procedures, the crew was required to maintain a minimum altitude of 4,500 feet until 11 km from the runway threshold, then descend to 2,650 feet. For unknown reasons, the crew initiated the descent prematurely, resulting in impact with terrain.
Investigation and Contributing Factors
The official investigation determined the probable cause to be controlled flight into terrain after the crew descended too low under VFR mode in IMC conditions. Contributing factors included: cancellation of the IFR flight plan for a VFR approach despite marginal weather and insufficient visibility; failure to follow the approach checklist; absence of an approach briefing; lack of callouts on approach; the second pilot not being procedurally involved in cockpit work processes and decision-making; reliance on the Flight Management System (FMS type III series) initially dedicated to flight inspection; and the flight engineer performing measurements.