What happened
During the landing phase, a twin-engine turboprop touched down approximately 1,900 feet past the threshold of a 6,000-foot runway. As the aircraft began its rollout, the pilot attempted to reduce engine power by pulling the levers back to the flight idle position. While attempting to engage reverse thrust, the pilot observed a red beta light illumination. Although manufacturer and operator protocols prohibited using reverse thrust while this light was active, the pilot moved the levers forward to exit the reverse range.
In the process of adjusting the levers, the pilot unintentionally moved them through the beta range and back into a flight idle setting, which produced positive thrust. This error prevented the aircraft from utilizing optimal aerodynamic braking. Consequently, the aircraft failed to stop within the remaining runway length, skidding toward the departure end of the runway. The aircraft then exited the runway and a taxiway in a skidding turn, eventually dropping over a 60-foot embankment before coming to a halt at the bottom.
Findings
Investigations into the accident revealed that there were no mechanical failures or anomalies present in the aircraft components. Testing of the beta light system determined that the red light illumination was caused by a simple switch malfunction rather than a critical emergency. Furthermore, the aircraft's computed landing distance for a 50-foot obstacle was 3,900 feet, assuming only braking and ground idle were used without reverse thrust.
Post-accident ground-taxi tests demonstrated that the aircraft could reach speeds exceeding 85 knots even with the power levers at idle. Flight simulator recreations based on flight data recorder information consistently resulted in runway overruns under similar conditions. It was also noted that the loss of reverse thrust capability would have had negligible impact on stopping distances in the United States, as performance credits for reverse thrust are not permitted in that region.