System dynamics application in air traffic management: A case study

In this paper, we present the results of a preliminary study which used SD to model the control of a single stream of aircraft. The initial model only considered longitudinal motion (no lateral or vertical flight path variations). Furthermore, the only controlled variable was aircraft speed. The goal of the study was to determine the effects on throughput and safety metrics through the variation of two parameters: 1) control algorithm, 2) overall control loop delay time, and 3) length of the reporting interval (distance or time between updates of aircraft state to air traffic control (ATC)). Two different speed control algorithms were compared. Throughput was measured by the average number of aircraft passing a fixed point per hour, over the course of the simulation(s). Safety was measured by the amount of time that the separation between any two (adjacent) aircraft fell below a safe minimum threshold value. The results show the relationship between the controlled parameters and the output metrics. Reductions in either control loop delay time and/or reporting interval length resulted in increased throughput and safety levels. Although this is a simple first step, we believe this is a novel application of SD, and points the way to applying SD to similar, but more complex problems in air traffic management (ATM).