Overall air traffic delays in the U.S. National Airspace System (NAS) are dominated by thunderstorm-related impacts. Moreover, convective weather delays continue to increase, even though a number of new weather information systems and traffic flow management (TFM) decision support tools have been deployed since 1999. Thunderstorms present a very difficult air traffic management (ATM) problem for a number of reasons:

• En route capacities are significantly reduced by phenomena that are difficult to predict in advance.

• Developing and executing convective weather impact mitigation plans is difficult when actions taken in response to the weather disruptions in one spatial region may cause significant air traffic management problems in another spatial region. The task is further complicated by the fact that plans must be developed and executed quickly to take advantage of short lived opportunities.

• Convective weather often presents unique management problems, since there may be subtle differences between any two weather events that pose particular decision-making challenges and there are no agreed-upon approaches (akin to the controller's handbook) for traffic management of convective weather impacts. As a result, personal decision-making styles on the part of individual decision makers, along with the person's background and experience, are important determinants of the overall use of the traffic and weather information to achieve goals appropriate for a given air traffic control (ATC) facility. Furthermore, in tactical (less than 2 hour) decision making, there is no one decision maker who can order the others to comply.

Research in the area of decision-making in difficult environments by Gary Klein and others offers several concepts that seem applicable to the design of convective weather decision support systems as well as user training. These concepts include models for decision making by individuals, the importance of shared situational awareness, and interpretation of team phenomena.

Recent operational experience in the use of improved convective weather decision support systems is reviewed in the context of the difficult decision-making research literature. Results from the 2005-06 quantitative studies of ATC productivity enhancements through use of the Corridor Integrated Weather System (CIWS) in the northeast quadrant of the U.S. suggest that the most important factors in improving decision making for the management of convective weather impacts is identifying key decision makers and providing them with appropriate decision support products and suitable training. Initial results of using an integrated weather/air traffic decision support tool - the Route Availability Planning Tool (RAPT) - to enhance the effectiveness of storm impact mitigation plan development and collaboration in the summer of 2007 are discussed.

This work was sponsored by the Federal Aviation Administration (FAA) under Air Force Contract No. FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the United States Government.