This paper discusses several of the most important operational aspects of terminal airspace utilization from an air traffic control viewpoint. Considerations include the work accomplished by the Department of Transportation's Air Traffic Control Advisory Committee, their FAA staff and industry representatives, as well as other selected efforts in analytical and dynamic simulation.Each of the subsystems which are involved in and therefore affect terminal/transition airspace use and capacity such as the airport, approach and landing, navigation, data acquisition, communications and air traffic control are discussed in terms of their relationship and interaction with capacity. The anticipated effect of increased automation in both the terminal and en route ATC systems and their interface is described. Possible tradeoffs between safety and expeditiousness are briefly examined.It is concluded that the expected increase in traffic will require major increase in system capability as well as changes in technique and philosophy only possible through extensive automation. In addition, new and improved National Airspace System elements will be required to cope with the resultant demand for capacity and safety.