Information about potential hostile aircraft from radar sites around the country was forwarded to a regional clearinghouse, like Otis Air National Guard Base, and then to ADC headquarters at Ent Air Force Base. It was then plotted on the world's largest Plexiglas board. Enemy bombers progress was tracked on the board using grease pencils. If there was a potential threat, interceptor aircraft were scrambled to the target. Because this process was cumbersome, it made a rapid response unattainable. An automated command and control system, Semi-Automatic Ground Environment (SAGE), based upon the Whirlwind II (AN/FSQ-7) computer was implemented to process ground radar and other sources for an immediate view of potential threats in the 1950s. There was an operational plan for a SAGE implementation for Ent by 7 March 1955.