Airspace Phase Transitions and the Traffic Physics of Interacting 4D Trajectories

This paper presents early progress in the development of a modeling and simulation capability derived from advancements in complexity science coupled with advancements in computational platforms for the simulation and analysis of emergent phenomena in the airspace. We present a research effort to test concepts of collective dynamics of large numbers of heterogeneous aircraft (thousands to tens of thousands) in the NAS undergoing continuous 4D trajectory replanning in the presence of noise and uncertainty while optimizing performance measures and deconflicting trajectories. We use a combination of modified genetic algorithms and pseudopotential methods acting on extended objects (trajectories) rather than on aircraft themselves to implement this capability. This is a natural way to preserve intent while deconflicting aircraft. Subjects under investigation include measures of fullness of the airspace, emergent structures arising from interacting trajectory optimization, tradeoffs between centralized and distributed optimization, and phase transitions in collective behavior ("traffic physics"). Our work is concentrated in the enroute airspace, but can in principle be extended to the terminal airspace. We describe the combined software and hardware platform we have built to realize a rapid-prototyping environment capable of investigating these questions at a realistic level of fidelity and in much greater than real time speed. Our simulation platform is built on the principle of minimum assumption and maximum emergence. There are no sectors, no flight level constraints, and control actions can be arbitrarily subtle and continuous in all four dimensions. Constraints up to and including the current NAS configuration can be "switched on" for comparison purposes. With this software simulation system, we can address implications for centralized versus decentralized control in a real-world system and explore alternative TBO concepts of operation, including applications such as game theory for economic considerations, bulk management of airspace phase state for capacity considerations, and well as policy and technology strategy evaluations.

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