Phantom braking

Phantom braking is an unintended emergency-braking event in which an autonomous or driver-assistance system commands sudden deceleration without an actual obstacle or threat present. Distinct from intentional defensive braking (where the system perceives a real risk that may or may not exist) and from communication-delay or sensor-noise artifacts.

The distinction matters because phantom braking has been a recurring NHTSA-flagged concern with Tesla Autopilot and FSD. It indicates perception-system false positives — the AI sees something that isn't there. High phantom-braking rates correlate with low perception confidence margins, which compound into safety risk because trailing vehicles don't expect the lead car to brake without cause. The NHTSA Preliminary Evaluation into Tesla's Autopilot specifically called out phantom-braking complaints as a structural concern.