What happened
The incident occurred during an instrument flight rules (IFR) approach when the pilot reported encountering significant ice accumulation on the leading edges of the wings. Despite activating all available icing protection systems, the pilot noted between one-half and one inch of ice buildup.
After breaking out of the cloud layer, the pilot initiated a descent with full flaps deployed, maintaining an airspeed between 110 and 115 knots. As the aircraft neared the runway threshold, the pilot began the flare maneuver but observed a mushy control response. The airspeed had decreased to approximately 100 knots at this point.
The aircraft stalled from an altitude of about 15 feet above the ground during the final phase of the landing sequence.
The investigation
The investigation focused on the flight data and pilot statements regarding the icing encounter and subsequent stall. No mechanical failures were identified prior to the stall. The primary finding was the loss of lift due to ice accumulation despite the use of anti-icing systems, combined with a low airspeed during the flare.
Findings
Contributing factors included the failure of the icing protection system to prevent ice buildup and the pilot's decision to descend with full flaps at a speed that became insufficient as drag increased. The stall occurred at a critical altitude with minimal recovery time.