ABSTRACT
Introduction The focus of this chapter is on the need to provide operational staff within the National Airspace System (NAS) with better feedback about the impacts of their decisions, helping them to understand how their actions interact with those of others to affect the performances of individual flights and the NAS as a whole. The discussion begins with a view of the NAS as a distributed work system that started to reach its limits in the 1990s in terms of its ability to meet demand by users, and that has been rapidly evolving in order to deal with this constraint.
