GATES: an airline gate assignment and tracking expert system

A description is given of GATES, an expert system that assigns gates to arriving and departing flights at New York´s John F. Kennedy International Airport (JFK). GATES uses flight information and knowledge about current constraints to produce possible gate assignment schedules. GATES is a constraint-satisfaction expert system. To make its decisions, it uses two types of production rule: permissive rules and conflict rules. Permissive rules determine when it´s appropriate to consider a particular gate for a particular flight, and permit the system to search the next level of rules to obtain an assignment. Conflict rules determine when particular flights cannot be assigned to particular gates. System operators can modify schedules by retracting rules, adjusting tolerances, and deleting information. The system was developed for a PC, thereby providing an efficient and flexible user environment. The approach is extensible to various engineering and industrial problems where limited resources and weakly defined constraints exist and in which scheduling must occur.<>