A Methodology for Macroscopic Airspace Traffic Risk Modeling and Assessment under Manned-unmanned Integrated Operations

Integrating manned and unmanned aircraft into shared airspace presents significant challenges to airspace safety assessment. Existing risk assessment studies primarily focus on tactical collision risk evaluation based on trajectory prediction, while strategic-level systematic risk assessment for airspace planning and design remains underdeveloped. To comprehensively evaluate airspace safety levels and support the safe large-scale integration of unmanned aircraft into controlled airspace, this study investigates a macroscopic traffic risk modeling and assessment method for integrated operations. Static risk indicators are constructed based on the structural characteristics of routes and intersections, incorporating geometric morphology and conflict-prone profiles. Dynamic risk indicators are proposed in both horizontal and vertical dimensions, based on traffic flow characteristics. By coupling static complexity with dynamic conflict risks, an integrated airspace traffic risk assessment model is established, reflecting both the static features of the airspace structure and the dynamic characteristics of aircraft operations. Using four sector areas in Shanghai as an example, a risk assessment is conducted under manned aircraft operational scenarios to validate the model's feasibility and effectiveness, and to determine the target safety level for the airspace. Simulation experiments are designed to explore the influence mechanism of the three parameters, speed difference, separation, and mix ratio, on risk under integrated operation. Based on the criterion of not exceeding the target safety level, an equivalent risk assessment approach is adopted to determine the feasibility of manned-unmanned integrated operations. The allowable number of unmanned aircraft that can be introduced into each manned route is evaluated. The results show that: ①Speed difference and separation are the core driving factors of risk. The influence of mix ratio on airspace traffic risk depends on the separation setting. When the minimum safety separation between manned and unmanned aircraft is significantly larger than that between manned aircraft or between unmanned aircraft, the risk peaks when unmanned aircraft account for about50% of the traffic mix. ②Complex interactions are observed among speed difference, separation, and mix ratio, with no additional higher-order coupling effects detected. ③High -risk initial periods are not conducive to the introduction of unmanned aircraft.