What happened
On April 24, 2019, a Cessna 551 Citation II/SP was conducting a training flight for type rating purposes at Siegerland Airport. The crew, consisting of a flight instructor and a student pilot, had previously completed three ILS approaches to runway 31. Due to changing wind conditions, the landing direction was changed to runway 13 for a visual approach.
During the final approach, the aircraft's airspeed decreased significantly. The student pilot, acting as the pilot flying, attempted to correct the descent angle by advancing the thrust levers to full power. However, the engines could not accelerate to sufficient thrust before touchdown. The aircraft touched down in the grass area approximately 5.2 meters before the asphalt threshold of runway 13.
Upon impact, the left main landing gear collapsed, damaging the left wing fuel tank. This caused a fuel leak that ignited, resulting in a fire. The aircraft slid along the runway for approximately 730 meters before coming to a halt. Both occupants evacuated via the right-side emergency exit without injury.
The investigation
The BFU investigation focused on the flight parameters and the crew's performance during the final approach. Radar data from DFS revealed that the aircraft's ground speed was continuously decreasing during the final segment. The investigation also examined the visual environment, noting that the terrain before the runway threshold was rising, which can create optical illusions.
Investigators noted that the PAPI (Precision Approach Path Indicator) lights for runway 13 were not switched on at the time of the accident. Furthermore, the aircraft was not equipped with a Flight Data Recorder (FDR) or a Cockpit Voice Recorder (CVR), which limited the ability to verify the exact airspeed and cockpit communications during the most critical seconds of the approach.
Findings
- The primary cause of the accident was an unstabilized approach and the failure to initiate a go-around.
- The student pilot's low experience level on the specific aircraft type led to high workload and a lack of continuous instrument scanning.
- The flight instructor failed to intervene in a timely manner to correct the deteriorating flight parameters.
- The approach was too short, providing insufficient distance to stabilize the aircraft's configuration and speed.
- An optical illusion caused by the rising terrain likely led the pilot to believe the aircraft was too high, resulting in a deliberately flat approach angle.
- The lack of active PAPI lighting contributed to the difficulty in maintaining the correct glide path.
- The approach was conducted too close to the airfield, leaving insufficient time for proper maneuvering.