  Coordination of local and global aerial traffic has become a legal and
technological bottleneck as the number of unmanned vehicles in the common
airspace continues to grow. To meet this challenge, automation and
decentralization of control is an unavoidable requirement. In this paper, we
present a solution that enables self-organization of cooperating autonomous
agents into an effective traffic flow state in which the common aerial
coordination task - filled with conflicts - is resolved. Using realistic
simulations, we show that our algorithm is safe, efficient, and scalable
regarding the number of drones and their speed range, while it can also handle
heterogeneous agents and even pairwise priorities between them. The algorithm
works in any sparse or dense traffic scenario in two dimensions and can be made
increasingly efficient by a layered flight space structure in three dimensions.
To support the feasibility of our solution, we experimentally demonstrate
coordinated aerial traffic of 100 autonomous drones within a circular area with
a radius of 125 meters.
