Free Flight in a Crowded Airspace?
American Institute of Aeronautics and Astronautics eBooks · 2001
In the report of the RTCA Free Flight Task Force, Free Flight is presented as a range of concepts, allowing selfoptimisation of the routes by the airlines. The document also describes a mechanism for airborne separation as a part of the Free Flight concept. Whether airborne separation is allowed depends on, among other things, the so-called “dynamic density”. This dynamic density is a measure of the density and the complexity of the traffic pattern. According to the original airborne Free Flight concept as described in the RTCA document, when the dynamic density is too high, less freedom will be allowed and separation will remain on the ground. This is based on the assumption that central co-ordination is required in these cases. However, this paper will try to demonstrate via analysis and simulation results, why it is precisely high density situations that require the power of a distributed system. It describes the concept as designed in the NLR study as an example of the implementation of the Free Flight concept. The lessons learned apply to most airborne separation concepts. The effect of a distributed ATM system will be illustrated by looking at some sample scenarios, the robustness and the conflict rates.