Additional (numerical) analytical models for computing airport delays have been developed over the last few years. Peterson et al. (1995) and Daniel (1995) describe two different models for computing delays at hub airports, which are characterized by sharp “banks” or “waves” of arrivals and departures. Hansen (2002) has used a deterministic model, based on the notion of cumulative diagrams, to compute delay externalities at Los Angeles International Airport. Finally, Long et al. (1999) and Malone (1995) present two dynamic queueing network models and their application to the study of congestion in the National Airspace System. Ingolfsson et al. (2002) offer a comprehensive survey and comparison of several alternative approaches to the analysis of nonstationary queueing systems.