Mode C Intruder Alert

(See also Conflict Alert) A function of certain air traffic control automated systems designed to alert radar controllers to existing or pending situations between a tracked target (known Instrument Flight Rules (IFR) or Visual Flight Rules (VFR) aircraft) and an untracked target (unknown Instrument Flight Rules (IFR) or Visual Flight Rules (VFR) aircraft) that require immediate attention/action. (FAA4)