I. Introduction
Civil aviation continues to grow. New vehicle types, such as uncrewed aircraft systems (UAS, or UA vehicles a.k.a. UAVs, or drones), and new services such as Advanced Air Mobility [1] will change or at least stress traditional air traffic management (ATM) operational rules. Air traffic density is also expected to increase, notably so for AAM in and near urban areas—sometimes termed urban air mobility (UAM), a subset of AAM.