Forward Collision Warning (FCW)

Forward Collision Warning (FCW) is an advanced driver-assistance system (ADAS) that warns the driver of a possible crash. The purpose of Forward Collision Warning is to prevent or reduce the severity of collisions. The system is mandatory in some countries.

How does FCW work?

Forward Collision Warning system uses sensors to monitor the vehicle’s speed, the speed of the vehicle in the front of it, and the distance between them. The sensors usually include radar and sometimes laser and camera, or a combination of these. Using the monitored information, FCW warns the driver when it detects an imminent crash. The warning includes blinking lights and beeping but sometimes also the vibration of the driver’s seat. Some systems tighten the seatbelts and precharge breaks to reduce the severity of the possible crash.

In many cars, FCW is combined with automatic emergency braking (AEB). When the system detects a collision and the driver doesn’t react, the system can take autonomous action to prevent the collision by breaking. Some systems also use steering to avoid collisions at higher speeds if adjacent lanes are clear.


FCW, together with AEB, has definitely reduced the number of collisions and made traffic safer for everybody. But it still has some limitations. Similarly to other ADASs, extreme weather conditions such as heavy snow, rain or fog can inhibit the system. To the frustration of drivers, the system sometimes works too well. It can occasionally be triggered by shadows on the road, road signs or parked cars situated in the middle of a curve by the roadside, and bending roads.

  • Collision avoidance system
  • Pre-crash system
  • Collision mitigation system