**This report was modified on April 23, 2010** On February 4, 2010, approximately 0215 central standard time, a Mitsubishi MU-2B-60, N644EM, was substantially damaged during a runway excursion at the Rick Husband Amarillo International Airport (KAMA), Amarillo, Texas. Night visual meteorological conditions prevailed at the time of the accident. The on-demand air taxi flight was being conducted under the provisions of Title 14 Code of Federal Regulations Part 135 on an instrument flight rules flight plan. The pilot and three passengers were not injured. The cross-country flight originated from the Dallas/Fort Worth International Airport (KDFW), Fort Worth, Texas at 0111 and was landing at its intended destination at the time of the accident. According to a statement provided by the airline transport pilot, while on approach to the airport, the pilot was informed by airport operations that the runway was covered with snow and ice. The pilot acknowledged and continued the instrument approach to the landing runway. While on approached the pilot was correcting for a right crosswind. The pilot kept a higher approach speed and landed 20 knots faster than the manufacturer's recommended landing airspeed. The airplane's right main landing gear touched down first followed by the left main landing gear and the nose gear. The airplane made an abrupt left turn and the pilot attempted to correct by depressing the right rudder pedal. The pilot lost control of the airplane and the airplane departed the left side of the runway on a heading that was approximately 30 degrees left of runway heading. The right main landing gear detached from the airplane and the airplane came to rest in the upright position. An inspector from the Federal Aviation Administration (FAA) responded to the accident scene and found no pre-impact anomalies with the airframe or engines. Denting, bending, and crushing damage was sustained to fuselage and the forward spar of the right wing. In an interview with the FAA inspector, a representative from airfield operations reported the runway's braking condition was estimated at "nil." This accident is part of the Safety Board's Human Fatigue Investigation Methodology Study. Forms completed by the pilot indicate that he awoke at approximately 0700 on February 3, 2010. The pilot had been awake for 19 hours and 15 minutes prior to the accident, but had only been on-duty for 4 hours and 15 minutes. At 0211, an aviation special weather report from KAMA's weather station reported winds from 120 degrees at 6 knots, 1/2 miles visibility with a runway 04 visual range of 4,000 to 5,000 feet, snow, freezing fog, an indefinite ceiling with a vertical visibility of 110 feet, temperature 28 degrees Fahrenheit (F), dew point 28 F, and a barometric pressure of 29.91 inches of Mercury.