Analysis of the contribution of flight plan route selection to delays and conflicts

The absence of predictability of flight operations in the National Airspace System (NAS) is a significant source of excess cost, requiring airlines to pad flight schedules, staff for worst-case scenarios, and build and maintain mitigation plans and equipment. Flight plan routes are selected by airlines to optimize their operations (e.g. minimize crew time, fuel burn and delays). In the absence of coordination of 4-D flight plan route selection, flights can converge at the intersection of the flight plan routes, creating delays and fluctuations in A ir Traffic Control (ATC) workload. Furthermore, due to the high degrees of freedom available in flight plan route selection and the varying constraints in the NAS, flight plan route selection can contribute to the stochasticity of the NAS. This paper evaluates the role of flight plan route selection in the stochasticity and performance of the NAS. One hundred simulations were run using Reorganized Air Traffic Control (ATC) Mathematical Simulator (RAMS). For every run, flights were randomly assigned flight plan routes. The results indicated that by randomly varying flight plan routes for 32% of the flight, the overall total delay had a standard deviation of 6849 minutes about the mean total delay of 161358 minutes The maximum total delay was 174559 minutes (8% above the mean) and the minimum total delay was 141876 (12% below the mean). The total number of en-route conflicts had a standard deviation of 201 about a mean of 29202 conflicts. The maximum number of conflicts recorded was 29751 (2% above the mean) and the minimum number of conflicts recorded was 28760 (2% below the mean). There was no correlation between the number of en-route conflicts and the total delays though the variance in total delays was more than en-route conflicts. An analysis of conflicts showed that about 80% of the conflicts were between flights flying in opposite direction to each other; about 15% were between flights flying in same direction, and - - the remaining 5% were between flight flying in perpendicular to each other.