Investigation Summary
The accident was precipitated by a rush to land in deteriorating weather conditions. The Fokker 50 was cleared for an approach while visibility was below the airline's minimums, catching the crew off guard. To lose altitude and speed rapidly, the 32 year old captain, who had 4,242 total flight hours, manipulated the power levers in a way that bypassed the flight idle stop. Due to a known but poorly understood design vulnerability in the Fokker 50's propeller control system, the propellers entered a ground start/reverse pitch regime while the aircraft was still airborne. This created massive drag and destroyed lift over the wings. The engines subsequently flamed out, and the aircraft stalled, impacting the ground in Niederanven, short of the runway.
Final Conclusions
The investigation by the Administration for Technical Investigations (AET) concluded the primary cause was the crew's decision to override the safety systems protecting against in-flight propeller pitch reversal. Contributing factors included the lack of a formal approach briefing, the pressure of operating in heavy fog, and a technical deficiency in the Fokker 50's anti-skid/propeller pitch protection logic that allowed the safety solenoids to be bypassed if certain cockpit actions were taken simultaneously.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
Propeller Pitch Control
The system governing the angle of the propeller blades; it was inadvertently moved into the 'Ground Beta' (reverse/flat) range during flight.
Flight Idle Stop
A mechanical and electrical barrier intended to prevent pilots from pulling power levers back into the ground range while airborne.
Anti-skid System
The system that provides the 'weight-on-wheels' signal to the propeller logic; a fault or specific manipulation can trick the plane into thinking it is on the ground.
Interesting Facts
- 01The crash remains the only fatal accident involving a Luxair owned and operated aircraft.
- 02The Captain and one passenger were the only two survivors of the initial impact and fire.
- 03The Fokker 50's safety system was designed to prevent reverse pitch in flight, but it relied on an anti skid system signal that could be bypassed by specific lever movements.
- 04Visibility at the time of the accident was significantly hampered by thick fog.
Safety Actions & Advisories
Fokker 50 Propeller Logic Modification
Source ↗Fokker issued a mandatory Service Bulletin to modify the propeller control system, ensuring that the secondary stop cannot be bypassed even if the anti-skid system fails or is manipulated.
Enhanced CRM Training
Luxair and other Fokker 50 operators revised Crew Resource Management training to emphasize the dangers of improvising descent profiles and bypassing safety interlocks.