This document details the highway accident of a 2007 Motor Coach Industries 56-passenger motorcoach with a driver and 52 passengers on board traveling southbound, descending a 5.6-percent grade leading to a curve to the left, 1,800 feet north of milepost 29 on U.S. Route 163. After entering the curve, the motorcoach departed the right side of the roadway at a shallow angle, striking the guardrail with the right-rear wheel and lower coach body. The motorcoach traveled approximately 350 feet along the foreslope, with the right tires off the roadway. The back tires lost traction as the foreslope transitioned into the drainage ditch. The motorcoach rotated in a counterclockwise direction as it descended an embankment. The motorcoach overturned, struck several rocks in a drainage ditch bed at the bottom of the embankment, and came to rest on its wheels. During the 360-degree rollover sequence, the roof of the motorcoach separated from the body, and 50 of the 53 occupants were ejected. Major safety issues identified by this accident investigation include driver fatigue, excessive vehicle speed, hours-of-service violations, motor carrier trip planning, motorcoach occupant protection, and emergency medical notification and response with regard to large motorcoaches traveling on rural roads. The Safety Board's recommendations to the Federal Interagency Committee on Emergency Medical Services, the Utah Bureau of Emergency Medical Services, the Federal Highway Administration, the American Association of State Highway and Transportation Officials, the National Association of State Emergency Medical Services Officials, the American Bus Association, the United Motorcoach Association, and Arrow Stage Lines are included. The Safety Board also reiterates one previously issued recommendation to the Federal Motor Carrier Safety Administration.