Book excerpt: The Nat. Weather Service's (NWS) weather products are a vital component of the FAA¿s air traffic control system. In addition to providing aviation weather products developed at its own facilities, NWS also provides staff onsite at each of FAA's en route centers -- the facilities that control high-altitude flight outside the airport tower. FAA and NWS have been exploring options for enhancing the efficiency of the aviation weather services provided at en route centers. This is a summary of a draft report that: (1) determines the status and plans of efforts to restructure the center weather service units; (2) evaluates efforts to establish a baseline of the current performance provided by these units; and (3) evaluates challenges to restructuring them.