What happened
During an instrument landing system (ILS) approach under instrument meteorological conditions, the aircraft experienced a significant power fluctuation. While the pilot initially reported the engines were at flight idle, subsequent statements indicated that power was being reduced toward flight idle when the left engine surged. This surge caused the aircraft to yaw to the right and drift to the left.
At approximately 300 feet above the ground, and roughly 0.25 to 0.5 miles from the runway threshold, the pilot established visual contact with the runway. At this stage, the aircraft was on the glideslope with an airspeed decreasing through 10-6 knots. In an attempt to recover, the pilot tried to execute a go-around; however, the throttles were reportedly difficult to manipulate. As the aircraft began to stall, the pilot lowered the nose, but the aircraft ultimately struck the terrain approximately 500 feet before reaching the runway threshold.
Findings
Investigations into the engine performance found no evidence of mechanical malfunctions in the left engine prior to the impact. Additionally, an examination of the cockpit revealed no issues with the operation of the throttle levers.
Discrepancies were noted in the crew's accounts regarding the engine power setting during the approach. While initial reports suggested the engines were at flight idle, later statements clarified that the power was being transitioned toward idle. According to the aircraft's flight manual, a torque setting of 1,100 lbs is required during a normal landing approach, with power reductions intended to occur only about 30 feet above the ground.
Weather conditions at the time of the accident were characterized by low visibility and heavy mist, with a ceiling of 100 feet. The accident occurred while the aircraft was operating near the minimum visibility requirements for the ILS approach.