An employee operating a service vehicle was in the process of unloading a member's vehicle from a flatbed tow truck. The employee lowered the flatbed s landing gear, and once the landing gear contacted the snow- and ice-covered road it took the pressure off the back tires (which the emergency brakes are attached to). This caused the tow truck to slide down the hill, and the deck of the bed crushed and lacerated the employee's right leg.