NAS-wide simulation and passenger itinerary performance: Implications for NextGen benefits analysis

NAS-wide simulations are one of the methods used to estimate annual system-wide benefits for Air Traffic Control modernization concepts-of-operations and technologies (e.g. NextGen/SESAR). These tools simulate the operation of up to 60,000 flights per day in various combinations of demand (i.e. flights) and capacity (i.e. airport and airspace capacity). The main input to the simulation is a schedule of flights (not a schedule of passenger itineraries). As a result, estimates of passenger delays assume all passengers are on direct itineraries only, and the impact of cancelled flights, missed connection, and airline network effects are not considered. This paper describes the results of an aggregate model of the operation of a hub-and-spoke network that takes into account passenger itineraries (i.e. direct and connecting) and a ll forms of itinerary disruptions (i.e. delayed flights, cancelled flights and missed connections). This model shows that the reduction in lost economic productivity generated from NAS-wide simulations is under-reported, as passenger trip delays due to delayed flights only account for approximately 40% of the total passenger trip delays. Furthermore, the model identifies the significant roles played by factors other than flight performance, such as airline itinerary structure, airline fleet mix (i.e. aircraft size), load factors and airline hub banking structure, on total passenger trip delay. For example, a 7-10% increase in load-factor can nullify the reduction in total passenger trip delay gained by a 5% improvement in on-time performance achieved by NextGen. The implications of these results on NextGen benefits assessments through NAS-wide simulation are discussed.