National Airspace System Stage A

The en route Air Traffic Control (ATC) system's radar, computers and computer programs, controller plan view displays (Plan View Displays (PVD)/Radar Scopes), input/output devices, and the related communications equipment which are integrated to form the heart of the automated Instrument Flight Rules (IFR) air traffic control system This equipment performs Flight Data Processing (FDP) and Radar Data Processing (RDP). It interfaces with automated terminal system and is used in the control of en route Instrument Flight Rules (IFR) aircraft. (FAA4)