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This article describes the structure of an APL interactive statistical graphics system called STATGRAPHICS. The system provides a comprehensive package of statistical routines which create an environment in which graphical techniques are fully integrated into basic statistical procedures. Individual procedures can be executed as separate APL functions or under the control of fullscreen menus. By using fullscreen panels and soft PF keys to control major statistical procedures, graphics becomes an integral part of the statistical analysis process.

A parametric time series model is employed to simulate the number of aircraft present in an air traffic control sector. Borrowing from the work of Box and Jenkins, the identification, parameter estimation and associated tests of adequacy are illustrated using data from a low altitude control sector. The fitted model provides a useful algorithm and reflects the time dependency which exists between the number of aircraft measured in consecutive time periods. The simulation is part of a larger air communications system simulation which is under development.