Abstract: Employee #1 was using a forklift to load and unload a trailer at the employer's loading dock. The tractor was not attached when Employee #1 started to work inside the trailer, but a coworker backed the tractor underneath the trailer while Employee #1 was still inside. As he backed out the forklift, the unchocked trailer moved, pinning the forklift against the loading dock. Employee #1 sustained serious internal/abdominal injuries and had to be cut out of the forklift by rescue personnel. The tractor's air-brake system was not connected to the trailer, and the coworker was not aware the forklift was inside. The employer had no formal forklift training program, and had not instructed workers to chock the wheels on vehicles being loaded or unloaded.