Collision risk analysis for alternate airspace architectures

This paper investigates an airspace architecture in which the core requirement is maintaining a target level of collision risk throughout the airspace, accounting for a diversity of aircraft types and a diversity of collision avoidance capabilities in different regions of the airspace. Because collision risk depends on both the density of aircraft and the collision avoidance capabilities of the aircraft involved, aircraft with better collision avoidance capabilities are able to fly in regions of higher density. Conversely, aircraft with lesser collision avoidance capabilities are restricted to less dense airspace or off-peak hours. This paper provides a framework for evaluating the proposed architecture, including a framework for evaluating collision risk based on the numbers and types of aircraft in the airspace and a framework for specifying the corresponding airspace admittance function. Properties of the airspace admittance function are explored and airspace designs are suggested based on the results. In particular, if high-equipped aircraft are not adversely affected by low-equipped aircraft, from a collision avoidance perspective, then the aircraft should fly together in the same airspace to maximize capacity. But otherwise, it may be better to segregate the aircraft types into distinct regions of airspace.