NTSB Identification: CHI04IA056.
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Scheduled 14 CFR operation of SKYWEST AIRLINES INC (D.B.A. Skywest Airlines)
Incident occurred Saturday, January 17, 2004 in Rapid City, SD
Probable Cause Approval Date: 02/02/2007
Aircraft: Bombardier CL-600-2B19, registration: N595SW
Injuries: 35 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

The airplane, being operated on a scheduled passenger flight, contacted the runway with the left wing tip, following a loss of control while landing. Weather conditions were varying due to freezing fog that was moving into and out of the area. The control tower at the destination airport was closed and the airplane was being controlled by a near-by approach control facility. After holding in-flight to wait for the weather to improve, the crew began the instrument landing system (ILS) approach when the visibility was reported as one-half mile. The captain stated that almost immediately upon entering the top of the fog layer they received an ICE caution message. He stated they turned on the wing and engine inlet anti-ice, but the ice accumulation on the windshield wipers was rapid and ice was accumulating on the winglet. The captain stated the approach lights came into sight when they were just above minimums and that he had the runway in sight at approximately 140 feet above the ground. The first officer then disconnected the autopilot and the nose came up slightly. He stated he informed the first officer to keep the nose down and add thrust. The captain stated they were slightly left of the centerline and the first officer was making "small" corrections back to the right. He stated the airspeed was just inside the "bottom of the bucket" and the trend vector was indicating a decrease in airspeed. The captain stated he "again said something about more thrust and keeping the nose down." He stated the airplane continued to move to the right of the centerline and he took control of the airplane. He stated the airplane responded "poorly" feeling "heavy and sluggish." The captain stated the airplane was close to the right side of the runway and he added thrust at which time the ailerons became more responsive. He stated the left wing dropped, scraping the runway, at about the same time the left main gear touched down. The captain stated the airplane bounced into the air then landed hard on the runway. The crew then taxied the airplane to the gate. The first officer stated that when the captain reported having the runway in sight, she transitioned her sight outside of the airplane and realized she needed to correct to the right. She stated she began the correction at which time the nose of the airplane pitched up, the airplane veered toward the correction, and it started sinking toward the right side of the runway. She stated the captain took over the controls, but the airplane dropped to the runway, bounced, and touched down harder the second time. The first officer, who was flying the approach, had about 15 hours of total flight time in the CL-600. The captain, who was also a check airman, had a total of 1,196 hours of flight time in the CL-600. At the time of the accident the local weather was reported as being visibility 1/4 mile in freezing fog, vertical visibility 100 feet. Inspection of the airport and airplane on the afternoon following the incident revealed ice was still visible on the antennas, windshield wipers, radome, winglets, and horizontal and vertical stabilizers. The main body of ice on these structures measured between one-half to five-eights of an inch thick and that the main body of ice plus the "ice spines" totaled three-quarters of an inch thick. A Kinematic parameter extraction showed loss of lift consistent with airframe icing but there was no early stall due to icing prior to touchdown and no indication that airframe icing had caused any loss of control. Marks on the ground and on the runway revealed the airplane 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 of the runway. The left wing tip then left a 63-foot long scrape mark on the runway, which was followed about 1,100 feet later by another set of tire marks. Data from the flight data recorder showed the airplane rolled slightly to the left followed by a roll to the right when the autopilot was disengaged. It then showed the airplane touched down with a vertical acceleration of at least 1.8g's. The airplane then became airborne in a 16-degree left bank, with a 5-degree nose up pitch at which time the ground and flight spoilers deployed contributing to the firmness of the 3.25 g touchdown one second later.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

The copilot's failure to maintain control of the airplane during the landing and the captain's delay in initiating remedial action. Factors contributing to the accident were the low ceiling and low visibility due to fog, and the aircraft's deviation from expected performance due to airframe icing.

Full narrative available

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