AbstractThis paper contains the results of an exploratory study aimed at developing a model which could form the basis of a comprehensive analysis of the Air Traffic Control system. This model could be used to evaluate the effects of proposed changes in the system.The results will be presented in three parts. Part I is intended to provide an overview of the results as well as a detailed description of a traffic flow model which computes the means and variances of delays experienced by individual aircraft. Since this model requires as an input a statistical description of the arrival and departure service processes, Part II describes a model which relates these processes to more basic quantities (e.g., aircraft mix, runway configuration). Since the models which are developed represent a physical system, the question of validation arises and is also discussed in Part II. Part III of the paper considers the question of designing a (real‐time) flow control system. It is formulated as a problem of minimizing a measure of system delay subject to constraints on the allowable departure and arrival times. Illustrative results are included through‐out the pa