Abstract: On October 11, 2011, Employee #1, a mechanic with three years of experience, was working alone to replace the brake shoes on a 57-passenger Van Hool bus. To elevate its right rear drive wheel for jack clearance, he backed the bus onto wooden ramps that were approximately 3 ft long and 12 in. wide. Employee #1 then placed a pneumatic bottle jack under the rear axle. After placing wheel chocks at the front and rear of the bus, he released the bus's parking brake, which was necessary to perform the brake work. Upon completing the work, he received a phone call. This distraction caused him to forget to set the parking brakes prior to lowering the bus to the ramps. Employee #1 laid on the ground beneath the bus in front of its rear wheel to turn the jack's bleed-down valve. He was very close to the elevated wheel because he was not using an extension tool. When he lowered the wheel onto the ramp, the wheel chock was unable to hold the bus. It rolled down the ramp onto Employee #1. He was hospitalized at UCSD Medical Center for chest injuries, including unspecified fracture(s).