By 2030, projected UAV operations may exceed one million concurrent flights in urban airspace, yet traditional fixed-distance separation methods fail to accommodate heterogeneous platforms. This paper introduces a three-tier hierarchical dynamic separation framework adapting minima across strategic (30–80 m category-specific baselines), pre-tactical (0.7–1.8× encounter-dependent scaling), and tactical (real-time 3D decomposition) timescales. Monte Carlo simulation across 100,000+ flight hours demonstrates 47% collision rate reduction versus fixed 30 m separation (0.008 vs. 0.015 per 1000 h, p < 0.001), 50% airspace utilization increase (18.4 vs. 12.3 UAVs/km3), 44% flight time penalty decrease (8.5% vs. 15.2%), and 99.97% ICAO-compliant TLS achievement (≤10−7 per flight hour) with real-time performance (78.5 ms for 20 UAVs). The framework provides an immediately deployable foundation for heterogeneous UAV traffic management.
Cao et al. (Sun,) studied this question.