Automatic Emergency Braking (AEB)

What It Means

Automatic Emergency Braking (AEB) is an Advanced Driver Assistance System (ADAS) that uses forward-facing radar, camera, or lidar sensors to detect potential collisions with vehicles, pedestrians, cyclists, or fixed obstacles, warn the driver, and, if the driver does not brake in time, automatically apply the brakes to prevent or mitigate the crash. AEB systems typically have two or three stages: a forward collision warning (visual, audible, and sometimes haptic), a brake pre-charge that reduces hydraulic lag, and the full automatic braking application. Most modern systems operate from about 5 mph to highway speeds, though pedestrian-detection AEB is typically rated only to 30-40 mph. NHTSA and IIHS research has found that AEB reduces front-to-rear crashes by approximately 50 percent, with even larger reductions for front-to-rear crashes with injuries. In 2016, 20 major automakers signed a voluntary commitment with NHTSA and IIHS to make AEB standard on 95 percent of their light-duty vehicles by September 2022, a target most met. In April 2024, NHTSA issued a final rule establishing FMVSS 127, making AEB mandatory on new light vehicles with phased compliance ending September 2029, projected to save approximately 360 lives and prevent 24,000 injuries per year. AEB-related recalls and investigations have grown rapidly: NHTSA has opened multiple investigations into Tesla Autopilot AEB behavior (PE21-020 and EA22-002, covering more than 800,000 vehicles and multiple fatal crashes into stationary emergency vehicles), Honda and Acura Sensing false-activation recalls, and software calibration recalls affecting Mazda, Subaru, and Nissan AEB systems. RecallCheck tags AEB-related recalls under the "Forward Collision Avoidance" and "Electronic Stability Control" categories from the NHTSA data feed.

Frequently Asked Questions