This article is about collision avoidance in automobiles; for other modes, see collision avoidance (disambiguation). A collision avoidance system is an automobile safety system designed to reduce the severity of an accident. Also known as precrash system, forward collision warning system or collision mitigating system, it uses radar (all-weather) and sometimes laser and camera (both sensor types are ineffective during bad weather) to detect an imminent crash. Once the detection is done, these systems either provide a warning to the driver when there is an imminent collision or take action autonomously without any driver input (by braking or steering or both). Cars with Collision avoidance are also equipped with adaptive cruise control, and use the same sensors like ACC.