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ADAS & autonomy

What Is Automatic Emergency Braking?

Automatic emergency braking, often shortened to AEB, is a driver-assistance feature that can apply the brakes when the vehicle detects an imminent collision risk and the driver has not reacted strongly enough.

Last reviewed: October 1, 2026CarGlossary Phase 2 glossary
Simple definition

AEB uses sensors such as camera, radar or sensor fusion to monitor the path ahead, estimate collision risk and command braking when the system determines that intervention is needed.

How AEB works

AEB starts with perception: the vehicle monitors the road ahead for vehicles, pedestrians or other relevant objects, depending on the system design. The software estimates closing speed, distance and whether the driver is already braking or steering away.

If the risk rises, many systems first warn the driver. If the driver still does not respond, the vehicle can pre-charge the brakes, increase braking force or apply emergency braking automatically. The exact sequence depends on the model, market and software calibration.

What sensors does AEB use?

AEB may use a front camera, front radar or both. Radar is strong for distance and relative speed, while cameras help classify lanes, vehicles and vulnerable road users. Some higher-end vehicles add more sensor types, but the software and validation matter as much as the sensor list.

AEB is closely related to automotive radar sensors, LiDAR and the wider ADAS stack.

What AEB cannot guarantee

AEB is not a promise that the vehicle will avoid every crash. It can be affected by speed, object type, weather, glare, dirty sensors, road geometry, vehicle loading, tire condition and whether the system is designed to detect a specific target.

Owners should read the vehicle manual carefully. Some systems work only in specific speed ranges or with certain object types, and some will reduce impact speed rather than stop completely.

What to compare as a buyer

  • Does it include vehicle, pedestrian and cyclist detection?
  • Does it operate at city speeds, highway speeds or both?
  • Does it work in daylight and darkness?
  • Is it standard on the trim or part of an option package?
  • Does the car show clear dashboard warnings when AEB is unavailable?
ADASAutomotive radar sensorAdaptive cruise controlLane keeping assistDriver monitoring systemEnd-to-end driving AI

Sources

CarGlossary note:

Feature names, connector support and EV specifications can vary by model year, trim, software version and market. Always verify the exact vehicle and charging-network documentation before buying or repairing.