What happened
On October 24, 2000, a Beech 300 was conducting a flight calibration mission to verify the functionality of NDB and DME ground facilities at the Donaueschingen/Villingen aerodrome. The aircraft, operated by a specialized flight inspection company, was performing a series of survey patterns in the area.
After completing the measurement program, the crew prepared for an approach to Donaueschingen. While flying under IFR at FL 100, the flight transitioned to VFR rules before reaching the Minimum Radar Vectoring Altitude (MRVA) of 6,400 ft. During the descent, the aircraft turned westward and then initiated a right turn to align with the extended centerline of runway 36. During this controlled descent, the aircraft struck a wooded ridge north of Blumberg at an altitude of approximately 2,700 ft MSL. The impact resulted in 4 fatalities and the destruction of the aircraft.
The investigation
The BFU investigation focused on the transition between flight rules and the crew's adherence to established procedures. Investigators examined the cockpit voice recorder (CVR) and radar data, which revealed that the crew was discussing their position and the upcoming approach shortly before the accident. The investigation also scrutinized the use of specialized equipment, specifically the use of the FMS III—a system intended solely for flight inspection purposes—for navigation during the approach. Furthermore, the investigators reviewed the company's operational manuals and the integration of the second pilot and flight engineers into the cockpit decision-making process.
Findings
- The primary cause of the accident was an unauthorized transition from IFR to VFR when the necessary meteorological requirements for VFR flight were not met.
- The descent was continued despite insufficient visibility, with ground visibility recorded at less than 500 meters.
- The aircraft descended below the Minimum Sector Altitude (MSA).
- There was a significant breakdown in cockpit resource management; the crew failed to perform an approach briefing, use approach checklists, or utilize required call-outs.
- The second pilot was not effectively integrated into the decision-making process or the operational workflow.
- Navigation data from the flight inspection-specific FMS III was used for the approach, which was inappropriate for standard navigation.
- The flight engineers provided navigational assistance that contributed to the loss of situational awareness regarding the terrain.