This note serves as an introduction to the work on Air Traffic Control currently being carried out at The College of Aeronautics. The basic principles of Air Traffic Control are examined and a mathematical basis for an analysis of the current and future ATC complex is discussed. The theory is based upon feedback control concepts using intermittent data. Examples showing the application to en-route airway and parallel track flying are given. These demonstrate the effect of positional data up-dating rate upon separation minima for both subsonic and supersonic aircraft. Application to both fixed route (Airway Control) and free-route (Area Control) are currently being considered. A full report is to be published at a later date.