FUZZY REASONING-BASED SEQUENCING OF ARRIVAL AIRCRAFT IN THE TERMINAL AREA John E. Robinson III, Thomas J. Davis, and Douglas R. Isaacson Abstract A fuzzy reasoning-based method for scheduling air traffic in the terminal area has been designed at the NASA Ames Research Center and operationally tested at the Dallas/Fort Worth Terminal Radar Approach Control (TRACON). The scheduling system sequences and assigns landing times to arrival aircraft by utilizing continuous updates of aircraft radar data and controller inputs. The scheduling algorithm contains a knowledge base which was refined during several thousand hours of controller-in-the-loop real-time simulations. This knowledge base applies fuzzy reasoning to evaluate propositions that consider both performance criteria and workload criteria, such as delay reduction and conflict avoidance. Operational test results show that the algorithm determines an efficient arrival plan to land aircraft in a manner acceptable to the air traffic controllers. This paper details the scheduling algorithm and presents data regarding its effectiveness in predicting the landing order of arrival aircraft.