Computing Danger Zones for Provably Safe Closely Spaced Parallel Approaches

The use of a differential game and an optimal control theoretic approach for computing danger zones for this particularproblemisnew.Thespaceoutsidethedangerzoneisdeemedprovablysafe,implyingthatduringblunder situations, emergency evasive maneuvers starting from outside the zone are guaranteed to be safe within limits on themaneuverseverity ofboth theblundering and evading aircraft. In addition,these zonescan becomputed online in real time with knowledge of the current state. The algorithm also provides the minimum runway spacings for independent approaches and the minimum longitudinal separation between aircraft for dependent approaches. Thealgorithmforcomputingthezoneshasbeenvalidatedwithoveronemillionsimulationruns,wheretheadjacent aircraft performed various blunder trajectories. The validation shows that the algorithm could successfully alert and prevent collisions in 100% of the simulations ran.