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The design of an interactive statistical graphics system in APL is described. Called STATGRAPHICS, the system is structured to create an environment in which statistical and graphics functions are integrated under flexible user control. An optional menu control scheme allows inexperienced users to execute functions under system control, while experienced users can access program functions directly. Procedure control functions, which generate fullscreen control pages and execute operations through defined program function keys, enable graphics to become an integral part of the statistical modeling 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.