In 1998 the Federal Aviation Administration (FAA) established the Free Flight Phase 1 program to provide new decision-support systems to a limited number of facilities in a relatively short time (by the end of 2002), with the goal to providing increased user benefits and maintaining current levels of safety. The FAA selected systems that were anticipated to meet those goals and had demonstrated support within the Air Traffic community.The User Request Evaluation Tool (URET) is one of the systems selected for inclusion in the program. URET was an operational prototype that had been deployed at two of the twenty Air Route Traffic Control Centers within the continental United States, Indianapolis and Memphis, in the 1996-97 timeframe. It is a decision-support tool used by the sector team in an Air Route Traffic Control Center. It is implemented at the Radar Associate Position to support the strategic operations of the team in an integrated fashion.With URET, controllers can provide better service by detecting and resolving problems earlier, maneuvering aircraft less off their filed route, and reducing some airspace constraints (such as static altitude restrictions). URET provides an automated conflict probe and trial-planning capability that informs the controller of projected conflicts and assists the controller in evaluating resolutions to determine if they are conflict free before the issuance of a new clearance and amendment. URET also provides flight data management capabilities that reduce controller dependence on paper flight strips.This paper describes the benefits to users of the National Airspace System attributable to URET. The metrics and measurements described are based on the experience with URET at the Indianapolis and Memphis en route centers. From early May 1999 until the deployment of the production system in January 2002, data was collected on a daily basis in order to assess the operational impact of the system. Analysis of the metrics has demonstrated that savings to airlines and general aviation (GA) attributable to URET derive most directly from savings in nautical miles flown from the issuance of lateral amendments by controllers and reduction in fuel burn from the lifting of static altitude restrictions. The savings in distance flown measured approximately 7,000 nautical miles daily for the two Centers. Reduction in fuel burn from the lifting of static altitude restrictions totaled approximately 950,000 gallons annually. The demonstrated benefits of URET resulted in the recent decision by the FAA to deploy URET at all twenty Air Route Traffic Control Centers within the continental United States.