What happened
During a training flight at La Ronge Airport in Saskatchewan, a Convair 580A, registration C-GSKJ, experienced a series of rapid-fire mechanical and procedural failures. While performing stop-and-go landing exercises, the aircraft entered a high sink rate on its third approach. In an attempt to arrest the descent, the crew applied power, but the rapid movement of the power levers caused the left engine to shut down via the autofeature system.
Following a touchdown and a subsequent bounce, the crew attempted a go-around. However, the aircraft failed to gain sufficient airspeed or maintain directional control. The aircraft entered a descending left-hand turn and struck trees in a wooded area near the airport. The accident resulted in one fatality and two serious injuries.
The investigation
Investigators examined the aircraft's flight data, which revealed that the aircraft was in a low-energy state during the final approach, with an airspeed significantly lower than previous successful circuits. The investigation focused on the interaction between the crew's power lever inputs and the aircraft's automated systems.
Technical analysis of the Convair 580A's autofeather system showed that rapidly advancing the power levers while in a low-thrust condition can trigger an unintended engine shutdown. Furthermore, the investigation looked into the crew's coordination and the availability of standardized operating procedures (SOPs), noting that the crew was operating in a high-workload training environment with inconsistent manual documentation.
Findings
- The crew attempted a go-around while the aircraft was in a low-energy state, preventing the necessary acceleration for a safe climb.
- Rapid power lever advancement caused an inadvertent shutdown of the left engine, which worsened the aircraft's energy deficit.
- The activation of the autofeather system contributed to a loss of situational awareness, making the crew unaware of the engine failure during the critical moments of the go-around.
- Inconsistent and ambiguous information regarding rejected landings in the available manuals led to confusion and a delayed retraction of the flaps.
- The pilot's decision to retard the power levers after the initial surge resulted in insufficient power from the remaining right engine to maintain control.