Introduction
The projected growth in air transportation demand over the next twenty years is likely to exceed the capacity of the unaided air traffic controller. Consenquently the past two decades have seen significant investment in the development of advanced air conflict detection and resolution algorithms. The aim of these algorithms is twofold: to increase capacity and to improve safety. Both the United States Federal Aviation Administration (FAA), and EUROCONTROL, recognize the need to develop support systems for both the tactical (radar controller) and strategic (traffic flow management) controller positions. At the tactical level these systems are particularly important for deconflicting air traffic [1], [2].