Research on the Classification of Air Route Intersections in the Airspace of China

Abstract

As the intersecting points of crossing traffic flows, air route intersections are the major bottlenecks in the world’s airspace due to restricted airspace and rapid growth of air traffic. In order to reduce controller workload and maintain traffic safety, air traffic operation units in China devised the idea of “overpasses” at busy intersections. The basic idea is to strategically separate flows of aircraft on intersecting routes vertically by allocating distinct flight levels to them. In practice, aircraft are required to maintain an agreed flight level en route long before they cross the intersection. With more and more “overpasses” being established, the available airspace is becoming more restricted, the result of which is a drop in the overall airspace efficiency. Therefore, the air traffic management community would benefit from a quantification indicator to determine whether an overpass should be established at a particular intersection. In this paper, such an indicator—a classification index—is proposed for air route intersections based on the calculated intersection complexity and collision risk. Additionally, according to the calculation results of the classification index for typical intersections in Chinese airspace, an intersection classification system is presented, which can serve as guidance for the establishment of overpasses in the future. A case study is provided to demonstrate the working of the system. The proposed intersection classification method should help decision makers better understand the operation characteristics of intersections in Chinese airspace and make informed decisions to balance workload and efficiency.