The Federal Aviation Administration’s (FAA) mission is to promote the safe, efficient, and expeditious flow of air traffic in the U.S. airspace system, commonly referred to as the National Airspace System (NAS). To accomplish its mission, FAA provides services 24 hours a day, 365 days a year, through its air traffic control (ATC) system—the principal component of the NAS. Predicted growth in air traffic and aging equipment led FAA to initiate a multibillion-dollar modernization effort in 1981 to increase the safety, capacity, and efficiency of the system. However, over the past 17 years, FAA’s modernization program has experienced substantial cost overruns, lengthy schedule delays, and significant performance shortfalls. Consequently, many of the benefits anticipated from the modernization program—new facilities, equipment, and procedures—have not been realized, and the efficiency of air traffic control operations has been limited. In addition, the expected growth in air traffic will place added strains on the system’s capacity. To get the modernization effort back on track and thereby address the limitations of the present system and meet the growing demand for increasing its capacity, FAA—in consultation with the aviation community—is developing plans to implement a phased approach to modernization, including a new concept of air traffic management known as “free flight.” To enable free flight, FAA intends to introduce a host of new technologies and procedures that will allow the agency to gradually move from its present system of air traffic control, which relies heavily on rules, procedures, and tight control over aircraft operations, to a more collaborative system of air traffic management. Under such a system, users would have more flexibility to select optimal flight paths, whose use would lower costs, improve safety, and help accommodate future growth in air traffic through the more efficient use of airspace and airport resources. Implementing this new air traffic management system will require FAA to introduce new technologies and procedures. FAA plans to test other new technologies and procedures through an initiative called Flight 2000 (now the Free Flight Operational Enhancement Program). FAA’s air traffic controllers direct aircraft through the NAS. Automated information-processing and display, communication, navigation, surveillance, and weather equipment allow air traffic controllers to see the location of aircraft, aircraft flight plans, and prevailing weather conditions, as well as to communicate with pilots. FAA controllers are primarily located in three types of facilities: air traffic control towers, terminal area facilities, and en route centers. The functions of each type of facility are described below. • Airport towers control the flow of aircraft—before landing, on the ground, and after take-off—within 5 nautical miles of the airport and up to 3,000 feet above the airport. A combination of technological and visual surveillance is used by air traffic controllers to direct departures and approaches, as well as to communicate instructions and weather-related information to pilots. • Terminal area facilities—known as Terminal Radar Approach Control (TRACON) facilities—sequence and separate aircraft as they approach and leave busy airports, beginning about 5 nautical miles and extending to about 50 nautical miles from the airport and up to 10,000 feet above the ground. • Air Route Traffic Control Centers (ARTCC)—or en route centers—control planes in transit over the continental United States and during approaches to some airports. Planes are controlled through regions of airspace by en route centers responsible for the regions. Control is passed from one en route center to another as a plane moves across a region until it reaches TRACON airspace. Most of the en route centers’ controlled airspace extends above 18,000 feet for commercial aircraft. En route centers also handle lower altitudes when dealing directly with a tower or after agreeing with a terminal facility. Aircraft over the ocean are handled by en route centers in Oakland and New York. Beyond the radars’ sight, controllers must rely on periodic radio communications through a third party—Aeronautical Radio Incorporated (ARINC), a private organization funded by the airlines and FAA to operate radio stations—to determine aircraft locations. • Flight Service Stations provide weather and flight plan services, primarily for general aviation pilots. See figure 1.1 for a visual summary of air traffic control over the continental United States and oceans. FAA will continue to operate en route, terminal, and tower facilities under the new air traffic management system; controllers in these facilities will be able to manage flight operations more collaboratively through the use of new decision support tools. For example, two new traffic management tools will allow en route and terminal controllers to better sequence aircraft as they move into the terminal environment—potentially increasing the system’s safety and efficiency. Free flight is a new way of managing air traffic that is designed to enhance the safety, capacity, and efficiency of the NAS. Under this new management system, air traffic control is expected to move gradually from a highly structured system based on elaborate rules and procedures to a more flexible system that allows pilots, within limits, to change their route, speed, and altitude, notifying the air traffic controller of the new route. In contrast, under the present system, while flight plans are developed in conjunction with air traffic control personnel, aircraft are required to fly along specific routes with minimal deviation. When deviations from designated routes are allowed—to, for example, avoid severe weather—they must be pre-approved by an air traffic controller. Under free flight, despite the availability of flexibilities to pilots, the ultimate decision-making authority for air traffic operations will continue to reside with controllers. While FAA and the aviation community have recently increased their efforts to implement free flight, the concept of free flight—allowing pilots to fly more optimal routes—is not new. In fact, the idea has been around for decades. With the development of navigation technology in the 1970s that allowed aircraft to fly directly from origin to destination without following fixed air routes (highways in the sky), the possibility of providing pilots with flexibility in choosing routes became viable. However, until recently, movement to develop the procedures and decision support systems needed to fully use this type of point-to-point navigation has been slow. In the last several years, because of the need to meet demands for increasing the system’s capacity and efficiency, FAA and aviation system users and their major trade organizations, representatives of air traffic control personnel, equipment manufacturers, the Department of Defense (DOD), and others (collectively referred to as stakeholders) have been working on plans to accelerate the implementation of free flight. To enable this new system of air traffic management, FAA plans to introduce a range of new technologies and procedures that will give pilots and controllers more precise information about the location of aircraft. This information will eventually allow for the distances between aircraft to be safely reduced—in turn, allowing more aircraft to operate in the system. For example, a new tool planned for use primarily in the en route environment will give controllers better information about the location of aircraft so that they can detect and resolve potential conflicts sooner than they can using current technology. Similarly, pilots will have more precise information about the location of their aircraft in relation to other aircraft. The use of these technologies will help to improve the system’s safety and capacity. While free flight will provide pilots with more flexibility, different situations will dictate its use. For instance, in clear, uncrowded skies, pilots may be able to use free flight fully, but some restrictions may be necessary during bad weather or in highly congested areas. “a safe and efficient flight operating capability under instrument flight rules in which the operators have the freedom to select their path and speed in real time. Air traffic restrictions are only imposed to ensure separation, to preclude exceeding airport capacity, to prevent unauthorized flight through Special Use Airspace (SUA), and to ensure safety of flight. Restrictions are limited in extent and duration to correct the identified problem. Any activity which removes restrictions represents a move toward Free Flight.” Stakeholders generally agree with the above broad concept—especially the idea that any activity that removes restrictions represents a move toward free flight. However, because users have different priorities based on their use of the system, they have different ideas about how best to implement this concept. RTCA has found that the implementation of free flight will affect a wide range of users—from part-time pilots to major airlines—depending on the operating environment. For example, in the en route environment, users will be allowed to fly more optimal routes between airports, thus saving time and money. In addition, under certain conditions, these users may be allowed to safely reduce the distance between themselves and other aircraft. Similarly, in airspace between 5 and 50 miles from the airport, the improved sequencing of traffic for approaches and landings will provide the potential for users to operate more efficiently than under the present system. Improved sequencing is expected to increase the number of aircraft that can safely operate in this environment at a given time. In addition, improved information sharing between pilots and controllers on the location of aircraft on an airport’s surface, for example, is expected to allow for better use of the airport’s surface capacity (such as runways and gates). Efficient use of this limited capacity is key to allowing users to maximize the benefits of operations under free flight. In light of FAA’s current efforts to replace its aging infrastructure and keep pace with increasing demands for air traffic services through the new system of air traffic management known as free flight, the chairmen and ranking minority members of the Senate Committee on Commerce, Science, and Transportation and its Subcommittee on Aviation asked us to monitor the implementation of FAA’s efforts and provide them with a series of reports. This initial report provides (1) an overview of FAA’s progress to date in implementing free flight, including Flight 2000 (now the Free Flight Operational Enhancement Program), and (2) the views of the aviation community and FAA on the challenges that must be met to implement free flight cost-effectively.