Event Overview
A scheduled passenger flight experienced a loss of control while landing, resulting in the left wing tip contacting the runway. The aircraft was operating under instrument flight rules with the destination airport's control tower closed, and approach control was providing guidance. After holding to await weather improvement, the crew initiated an instrument landing system (ILS) approach when visibility was reported as one-half mile.
Crew Accounts
The captain stated that almost immediately upon entering the fog layer, an ICE caution message appeared. They activated the wing and engine inlet anti-ice, but ice accumulated rapidly on the windshield wipers and winglet. The approach lights became visible just above minimums, and the captain had the runway in sight at approximately 140 feet above ground level. The first officer disconnected the autopilot, causing the nose to rise slightly. The captain instructed the first officer to keep the nose down and add thrust. The aircraft was slightly left of the centerline, and the first officer made small corrections to the right. The airspeed was inside the lower limit of the acceptable range, and the trend vector indicated decreasing airspeed. The captain again urged more thrust and nose-down input. As the aircraft moved right of the centerline, the captain took control. The aircraft responded poorly, feeling heavy and sluggish. Near the right side of the runway, the captain added thrust, and the ailerons became more responsive. The left wing dropped and scraped the runway about the same time the left main gear touched down. The aircraft bounced, then landed hard. The crew taxied to the gate.
The first officer reported that when the captain announced having the runway in sight, she transitioned to outside visual cues and realized a correction to the right was needed. As she began the correction, the nose pitched up, the aircraft veered right, and it started sinking toward the right side. The captain took over, but the aircraft dropped to the runway, bounced, and touched down harder a second time. The first officer had approximately 15 hours of total flight time in the CL-600. The captain, a check airman, had 1,196 hours in the CL-600.
Weather and Ice Conditions
At the time of the incident, local weather was reported as visibility one-quarter mile in freezing fog with vertical visibility of 100 feet. An inspection the following afternoon revealed ice still present on antennas, windshield wipers, radome, winglets, and horizontal and vertical stabilizers. The main body of ice measured between one-half and five-eighths of an inch thick, with ice spines totaling three-quarters of an inch.
Aircraft and Runway Evidence
Kinematic parameter extraction indicated a loss of lift consistent with airframe icing, but no early stall due to icing occurred prior to touchdown, and no indication that airframe icing caused a loss of control. Ground marks showed the aircraft initially touched down 1,976 feet from the approach end of the runway, with the right main landing gear in the grass off the side. The left wing tip left a 63-foot long scrape mark, followed about 1,100 feet later by another set of tire marks. Flight data recorder data revealed a slight left roll followed by a right roll when the autopilot was disengaged. The first touchdown had a vertical acceleration of at least 1.8 g. The aircraft then became airborne in a 16-degree left bank with a 5-degree nose-up pitch, at which point ground and flight spoilers deployed, contributing to the firmness of a 3.25 g touchdown one second later.