Study of Capacity and Conflict Resolution in a Hexagonal Airspace Sector

As the NAS becomes increasingly crowded with the current rate of growth in air traffic, there are many ongoing studies focusing on how to alleviate the pressure on the airspace system in the United States. One such method is to focus on the structure of the airspace in hopes of reducing the workload of controllers and increasing capacity. Currently, the various enroute sectors above the United States are of various shapes and sizes and have been continuously updated to reflect the needs of the changing volume of traffic moving through the airspace. In the future, it may be beneficial to incorporate a new design for each sector such that they are all of a uniform shape and size. This would allow for the introduction of set of standard procedures that would make flight paths more predictable, reduce the required training and strain on controllers moving to different sectors, and would also ease the development of computational tools that could be used to optimize the capacity in each sector. One shape of such a sector that is studied in this paper is the hexagon. For the purposes of this paper, a hexagon with sides of 250 NM was chosen, but similar methods could be used for a hexagon of any size. A simple procedure was also chosen. For this procedure, traffic would enter through the middle of three adjacent sides and exit out of the middle of the other three adjacent sides. Aircraft would fly on a straight line through the sector, making heading changes only when they enter at the boundary or when they exit at the boundary. This can be seen in Figure 1. One strength of this procedure is that it allows for two or three parallel streams in each flow direction. The flow directions would be reversed at different altitudes to allow for flights in all directions. The paper is divided into the following sections. Section III. describes the methodology used to determine the maximum rate at which aircraft can enter the sector as a function of traffic distribution. It was assumed that all aircraft are flying at the common speed of Mach 0.8 and the time of their entrance into the sector is optimized. Section IV. details the approach used to deconflict the flows in case the Requested Time of Arrival (RTA) at the entrance to the sector is not met.