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Securing the Future of U.S. Air Transportation: A System in Peril 1 Foundation for Change At the request of the National Aeronautics and Space Administration (NASA) and the Federal Aviation Administration (FAA), the National Research Council (NRC) established the Committee on Aeronautics Research and Technology for Vision 2050 to assess (1) the long-term visions and goals for U.S. civil aviation, as described in five key documents produced by the federal government, and (2) technology goals for the year 2050 (see Appendix A). The committee issued a letter report on August 14, 2002, to address the first topic.1 The substance of that letter has been incorporated into this report, which also addresses the second topic. This chapter describes key elements of the future vision and the need for specific goals to support that vision. After acknowledging the limits of any effort to look far into the future, the chapter then describes the primary challenge to achieving the future vision and previews a process for making needed changes. Three subsequent chapters address research related to improving (1) air transportation system performance, (2) system-level modeling of the air transportation system, and (3) performance of individual aircraft. The final chapter concludes with a summary recommendation regarding the process for change that is vital to securing the future of the air transportation system. A complete list of the findings and recommendations contained in this report then follows, along with appendixes that contain the statement of task and the study approach executed by the committee, a comparative assessment of future goals and visions, brief biographies of the members of the committee, a descriptive catalog of propulsion system concepts, and a description of four levels of system models. VISION AND GOALS To continue to reap the benefits that the air transportation system provides, the U.S. visions examined by the committee consistently identify three main thrusts that long-term aeronautics research should address: safety and security, capacity, and environmental compatibility (noise and emissions). At the same time, the U.S. visions and goals consistently overlook several key items: a description of the overall process for developing and achieving a widely endorsed long-term vision for the air transportation system, a clear set of guiding principles, and a strategy for overcoming transitional issues. In assessing the U.S. goals and visions, the committee also examined a comparable vision for civil aeronautics in Europe. The European vision highlighted two additional areas that are missing from the U.S. visions. The latter do not include as a goal the satisfaction of consumer needs—that is, the quality and affordability of air transportation—perhaps because consumers do not seem to have been consulted when the U.S. visions were formulated. This could be a major oversight, given the large role that consumer demand for low cost and convenience (e.g., frequent departures) plays in business decisions made by industry.2 Also, although the U.S. visions as a whole recognize that national well-being depends on a national transportation system with a strong 1 National Research Council (NRC). 2002. Aeronautics Research and Technology for 2050: Assessing Visions and Goals—Letter Report. Washington, D.C.: National Academy Press. Available online at <www.nap.edu/catalog/10518.html>. 2 This report uses demand generally to refer to both consumer demand (the amount of air transportation services purchased, in terms of passenger-miles and cargo-ton-miles) and the load imposed on the air traffic control system (in terms of aircraft operations). Demand reflects the response of consumers to prices and the shape of the air transportation demand curve. Consumer demand is closely linked to demand on the air traffic control system, as individual airlines adjust routes, schedules, levels of service, prices, etc., to both stimulate and satisfy consumer demand.
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Securing the Future of U.S. Air Transportation: A System in Peril aviation element, they do not include primacy of the U.S. aeronautics industry as a goal. Competitiveness is so central to the European vision, by contrast, that it appears in the title of the document that defines this vision: European Aeronautics: A Vision for 2020—Meeting Society’s Needs and Winning Global Leadership. The vision for the U.S. air transportation system should be supported by research and technology goals leading to improved system performance. Measurable long-term targets should be established to assess progress toward those goals. Ideally, goals should be Ambitious enough to be challenging, without going beyond the limits of what is practical given likely constraints imposed by the current and future state of scientific and engineering knowledge, economics, and other nontechnical factors. Linked to specific benefits—for example, noise goals that will end the exposure of communities near airports to a day-night average sound level greater than 55 dB. Focused on areas in which government research can have a direct impact. Supported by research that demonstrates that the goals will result in the intended outcome—for example, that noise will be substantially eliminated as a constraint on airport operations. Time-phased, with different levels of performance established over different periods of time where appropriate. Organizational goals should be dynamic to respond to a changing world and changing requirements. NASA recently replaced time-phased, quantitative goals for aeronautics research and technology (e.g., “double the aviation system capacity within 10 years, and triple it within 25 years”) with open-ended, qualitative goals (e.g., “enable more people and goods to travel faster and farther, anywhere, anytime, with fewer delays”). Quantifiable goals may be difficult to establish for research leading to improved understanding and for research related to customer satisfaction, competitiveness, and improving human-computer interactions. However, limiting research to areas with easily quantifiable goals would reduce the scope of research to a subset of the overall problem. Furthermore, quantifiable goals could be readily established in many areas, and even as NASA moves away from quantitative research goals, the report of the Commission on the Future of the U.S. Aerospace Industry (2002) recommends the adoption of specific, quantifiable aerospace technology demonstration goals for capacity, safety, mobility, and environmental effects as a national priority. In considering how research could improve the performance of the air transportation system, the committee took a broad view of performance that considers the particular needs of customers, airlines, and manufacturers. This broad view includes the following parameters (listed alphabetically): Comfort en route en route accommodations transfer activities, including airport amenities Convenience of passenger travel and air freight service availability of service at times desired by customers availability of service to desired departure and destination locations ease of passenger ingress and egress, cargo handling, and aircraft handling, especially as it relates to customer satisfaction and capacity constraints total travel time Cost of moving passengers and cargo cost of developing and manufacturing new aircraft and aircraft systems cost of passenger and freight operations ticket prices for passenger travel and prices paid for freight services Societal impact consumption of nonrenewable fuels effects on the national economy (employment, etc.) emissions land use noise reduced congestion in other modes of transportation safety and security Airline economics are complex, and the relationship between technology and some of the above parameters is indirect and difficult to quantify. For example, technological efficiencies will not be able to compensate for the economic inefficiencies that occur when reduced demand (or a poorly structured route system) produces low load factors, resulting in high costs per passenger-mile (or cargo-ton-mile). Furthermore, in the short term, ticket prices are often driven more by competitive pressures and the laws of supply and demand than by the productivity and efficiency of the aircraft used to provide transportation services. Ultimately, however, improved performance (that results in lower costs) is necessary because prices that fall below the service providers’ average total costs are economically unsustainable without external subsidies. Recommendation 1-1. Goals. The future vision for the air transportation system should be supported by research and technology goals leading to improved performance. Measurable long-term targets supported by sound analyses should be established to assess progress toward the goals. Research should support the establishment of quantifiable goals in areas where progress is difficult to measure.
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Securing the Future of U.S. Air Transportation: A System in Peril BEYOND THE HORIZON When considering the future of the U.S. air transportation system, the committee sees a fundamental difference in expectations between (1) the next 25 years or so and (2) the quarter century ending in 2050. Commercial aircraft and air traffic management systems have lifetimes on the order of 25 years. In addition, the commercial aviation industry—as well as the government’s certification processes—are justifiably cautious when it comes to the acceptance of new concepts and technologies. As a result, the gestation period between initial development of a new technology or concept and the point where it sees widespread operational use is often measured in decades. Accordingly, the state of the air transportation system in 2025 will largely be defined by systems that are already operational and the implementation of existing research. In other words, 2025 is imaginable in terms of current technology. The air transportation system of 2050, however, could incorporate technologies that are as yet undiscovered or that exist but will be used in ways as yet unimagined. However, the air transportation system of 2050 will benefit from new ideas only if long-term research—and the technology recommendations made in subsequent chapters of this report—are pursued with enough vigor to ensure that the long gestation associated with new technological approaches and operational concepts will be completed by then. Looking backward to 1953 illustrates the challenge of predicting the future 50 years hence. The personal computer had not yet been invented in 1953, yet any 50-year prediction of aviation requirements issued in 1953 that did not account for this unforeseen technology would look absurd today. What new technologies will take aviation in unexpected directions over the next 25 to 50 years? An authoritative answer is impossible, so long-range plans must be flexible enough to accommodate the unexpected. For decades, railroads were the preeminent long-distance transportation system. But the U.S. rail system of today is vastly different from the system of the early 1900s. Railroads are still a dominant provider of cargo service, yet railroads are now a minor provider of long-distance passenger service, and the passenger service that survives has done so only because the government subsidizes operational and capital costs. For all transportation modes flexibility in the face of changing priorities and challenges is essential. CHALLENGE Current U.S. visions for civil aviation correctly point out the importance of civil aviation to the national economy and overall standard of living. People want to travel quickly and comfortably. Businesses and their customers want products delivered overnight. Per capita use of aviation is higher in the United States than any other country in the world, and nonbusiness travel accounts for more than 50 percent of passenger air travel. The availability of quick and affordable options for long-distance travel increases demand. That will probably always be the case. To the extent that air transportation can continue to satisfy these universal human desires safely, reliably, and affordably, air transportation will remain relevant. Yet many people do not enjoy air travel. Technologies associated with videoconferences, netconferences, and virtual reality experiences are gradually increasing the ability to be “present” without being there. Crises such as the shutdown of the air transportation system following 9/11, security concerns that still keep many air travelers at home, security procedures that increase travel time, international conflicts, a downturn in the national and global economies, and the SARS epidemic are providing incentives for the corporate world to find new ways of doing business remotely. The same concerns are also inducing many leisure travelers to plan vacations that do not require travel by air. Though the committee does not believe that current problems are a harbinger of a change in long-term trends, changes in the way customers use the air transportation system—and changes in the way government and industry structure and use the air transportation system—need to be anticipated wherever possible. For example, a significant shift of airspace use away from business travel to a broad mix of nonbusiness travel and cargo—even as overall demand continued to increase—would have significant impact on service providers and the air traffic control system. Missing such a trend could result in a misdirection of research. Two summers ago the air transportation system experienced extraordinary delays as the demand for air travel pushed traffic to the limit and disrupted schedules in many parts of the system. Although the air transportation system had faced extensive delays before, the crisis two summers ago was quantitatively the gravest in history. Since then, the demand for air transportation has been curtailed by the factors noted above. Today, undercapacity is no longer an immediate problem in most parts of the U.S. air transportation system, and air transportation faces the peril of economic devastation as major carriers reduce service and file for bankruptcy. Although the committee believes that vigorous action is needed to prevent capacity problems in the years ahead from producing unacceptable delays in air transportation, the future is by nature uncertain. But some things are certain. Agility in responding to changing situations and trends is vital. National leadership is essential for motivating and directing change. A robust suite of systems models is needed to explore future possibilities and secure the future regardless of what eventually comes to pass. Lastly, uncertainty about the future must not stand in the way of aggressive action to address the problems that are expected. The only alternative is to abandon the opportunity to get ahead of future problems and simply react to crises as they occur. In the past, short-term downturns in demand for air transportation have always been followed by a return to steady
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Securing the Future of U.S. Air Transportation: A System in Peril growth in demand, and the committee believes that this pattern will repeat itself. As a result—despite the current situation—the most critical issue facing all aspects of the air transportation system over the long term is likely to be growth in demand for air transportation. To increase capacity, the system can be expanded and the capabilities of the system can be increased, but many elements of the air transportation system—including many major airports—are constrained. In some areas, significantly expanding the system infrastructure would be expensive, time-consuming, and extraordinarily difficult. Issues associated with safety, security, and environmental compatibility are also exacerbated by greater demand, and the effectiveness of currently envisioned near-term solutions in each of these areas would be diminished if demand for air travel in the United States doubles over the next 10 to 35 years, as currently projected.3 Air transportation leadership must remain mindful of changes, both within and without the air transportation system, and remain flexible if the system is to remain vital over the long run. Finding 1-1. Challenge of Increased Demand. The continued success of aviation and the benefits that it provides will require changes to accommodate increased demand. This is the most critical long-term issue facing all aspects of the air transportation system. Issues associated with safety and security, capacity, environmental compatibility, and consumer satisfaction are all exacerbated by greater demand, and the effectiveness of near-term solutions in each of these areas will be diminished by long-term growth in demand for air transportation in the United States. Business as usual, in the form of continued, evolutionary improvements to existing technologies, aircraft, air traffic control systems, and operational concepts, is unlikely to meet the challenge of greatly increased demand over the next 25 to 50 years. The importance of altering historical trends is particularly important to limit the environmental effects of aviation. Between 1976 and 2001, the demand for air transportation increased by 250 percent, yet the fuel efficiency (amount of fuel consumed per passenger-mile or ton-mile of cargo) of large commercial aircraft in the United States, which reflects improvements in the design of both the airframe and the propulsion system, improved by only 50 percent. As a result, air transportation is burning more fuel and producing more emissions, which contribute to environmental problems locally and globally. Fuel consumption and engine emissions have not gone up as much as they would have without new technology, but they are going up nonetheless. A similar situation exists with noise. Although each new generation of aircraft produces less noise than older aircraft of the same size, aircraft noise is still an unwelcome part of life in many airport communities, and limits on aircraft noise continue to constrain aircraft operations at many airports. The disparity between (1) the rate at which demand is increasing and (2) the rate at which technology is reducing aircraft noise and emissions is becoming increasingly difficult to overcome because technical advances are becoming increasingly difficult to achieve. For example, the rate of improvement in specific fuel consumption has long been predicted to diminish as turbojet engines approach their theoretical limits (Dawson, 1968). NASA’s now obsolete goals for aeronautics research recognized the importance of accelerating the rate of technological advances. Meeting the noise goals adopted by NASA in 1997 would have required a dramatic break from historical trends (NRC, 2002), but NASA has replaced those goals with new research goals that lack any measurable targets. Revolutionary changes are needed in more than just aircraft and aircraft systems. Much of the current effort to increase system capacity is focused on eliminating delays caused by specific constraints, such as restricted visibility or other forms of adverse weather en route, in the terminal area,4 and at airports. The problem faced over the 2050 time frame, however, is quite different. To increase passenger throughput enough to keep up with increased demand, eliminating the effects of adverse weather is not enough; in addition, the baseline capacity of the system in good weather must also be greatly increased. This may require widespread adoption of operating concepts that use runways and airspace in new ways. It may also require new paradigms for the air traffic management system as a whole, to leverage the significant advances that are being made in information technology and global surveillance, communication, and navigation capabilities. Travel by air in the United States is extraordinarily safe, and industry and government make a tremendous effort to keep it so. Increased demand over the next 25 to 50 years could result in more accidents. More traffic could stress overloaded portions of the system to the point where accident rates increase, and even if the accident rate stayed the same, more traffic would result in more accidents per year. Historically, however, safety improvements have been able to reduce the total annual number of fatalities from commercial aircraft accidents despite increased demand. In fact, during 2002 U.S. airlines experienced no fatal accidents. Future changes to the air transportation system to increase 3 Forecasts of future demand by the government, industry, and other organizations and individuals predict that air travel will double in the next 10 to 35 years (Boeing, 2000; Neufville, 2000; Federal Transportation Advisory Group, 2001; NASA, 2002; NRC, 2002; RTCA Free Flight Steering Committee, 2002; FAA, 2003). Although the rate of increase is uncertain, all agree that air traffic operations will increase substantially over the long term. 4 Terminal areas include the airspace within about 50 miles of major airports.
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Securing the Future of U.S. Air Transportation: A System in Peril capacity could conceivably create unexpected hazards that lead to a higher accident rate. However, accidents are so unacceptable that such hazards would be corrected as quickly as possible, even if it meant undoing capacity enhancements. A similar philosophy applies to security, in the sense that security measures take precedence over capacity concerns. The primary challenge for security-related technologies is to increase security without constraining capacity. As with the other major thrusts, long-term plans for developing technology to improve security should be based on a systematic approach that assesses the specific problems that need to be addressed and targets technologies accordingly. For example, security systems should be designed to predict and adapt to future threats to ensure that we are not in a constant state of preparing to “fight the last war.” Achieving this goal is difficult, because the foreseeable future can change in the instant that tragedy strikes in the form of a previously unforeseen failure of existing safety and security systems. Addressing future challenges is also complicated because isolated efforts to achieve one goal may make it more difficult to achieve other goals. In addition, different stakeholders in the aviation community (manufacturers and operators; executives and employees; pilots, controllers, and passengers; local, federal, and state governments; regulators; the military; general aviation; and others) have different priorities. For example, everyone is in favor of reduced environmental impacts. However, passengers are very price conscious, and airlines that consistently fail to make a profit ultimately cease to exist. Therefore, advanced technology that reduces engine emissions but increases costs will be difficult to sell to airlines that are already meeting regulatory standards—unless those standards are expected to become more stringent. Finding 1-2. Going Beyond Business as Usual. Business as usual, in the form of continued, evolutionary improvements to existing technologies, aircraft, air traffic control systems, and operational concepts, is unlikely to meet the needs for air transportation that will emerge over the next 25 to 50 years. The likely result would be an air transportation system where growth in demand has been greatly curtailed by undercapacity in the air traffic management system; the environmental effects of aviation; customer dissatisfaction with available levels of comfort, convenience, and cost; and/ or factors related to safety and security. The Big Question. How can change within the air transportation system be accelerated quickly enough and directed with enough agility to avoid problems and achieve future goals while managing (1) the influence of increased demand and other external pressures and (2) conflicts between different goals and stakeholders? How can the system be prevented from changing too slowly, drifting, or going in the wrong direction? The answer is to develop an improved process to guide and facilitate change. Such a process is discussed in more detail below and in Chapter 5, which presents the committee’s recommendation to institute an effective process for change. CHANGE The process of organizing a long-term research and technology program for civil aviation should start with a systematic statement of the underlying problems and a unified national vision to ensure that efforts by individual departments and agencies of the federal government respond to these problems in a synergistic fashion. Currently, however, most of the five vision documents examined by the committee have not been endorsed by the heads of the agencies who chartered them, and they contain goals that are inconsistent with the research and acquisition budgets of the federal agencies responsible for aviation. The situation raises questions about the relevancy of existing visions and demonstrates the need for federal agencies involved in civil aeronautics research and technology to support and implement a unified national vision. The Department of Transportation has primary responsibility for civil aviation policy and regulation. Through the FAA, the Department of Transportation also has purview over the certification of civil aviation equipment and personnel, development and operation of the air traffic management system, and system safety. The functions and vital interests of many other government agencies are also related to the development and operation of the U.S. civil air transportation system. The federal government recently established a joint aviation systems program office involving the FAA, NASA, the Department of Commerce, the Department of Homeland Security, the Department of Defense, and other federal agencies. This office has the potential to enhance interagency cooperation in supporting the modernization of the air transportation system. Operational concepts can help to develop the functional requirements for a new system by describing how it will perform, including the allocation of roles and responsibilities to interconnected systems and humans. Operational concepts may include system development, production, deployment, training, operation, maintenance, upgrading, and decommissioning. For example, the operational concept for an air traffic management system that allows parallel operations on closely spaced runways in low visibility conditions would describe approaches for dealing with safety concerns (e.g., wake vortices and collision), roles and responsibilities of pilots and controllers, equipment requirements (for airports and aircraft), and regulatory changes. At a higher level, operational concepts can be used to suggest how new kinds of aircraft, air traffic management procedures, systems, regulations, and business practices could improve the performance of the air transportation system.
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Securing the Future of U.S. Air Transportation: A System in Peril New technologies and operational concepts should be assessed in terms of their ability to solve the key problems of the air transportation system of the future. Such an assessment requires modeling at the system level how the air transportation system is affected by various technologies, operational concepts, and external factors (e.g., economic conditions, intermodal travel options, and the future state of the international air transportation system). To facilitate the planning of long-term research, models should be able to assess the impact of proposed technologies and operational concepts beginning at the earliest stages of development. The assessments should also be focused on the overall performance of the air transportation system rather than on individual parameters or components of the system. For example, in the next 50 years it will probably become technologically feasible to replace pilots and/or air traffic controllers with automated systems, at least under nominal operating conditions. But to what extent would such an approach solve the key problems of today, and what new problems might such a solution introduce, especially during emergencies? The guiding principle should be to design synergistic partnerships between humans and automation that result in better performance in all operating conditions than either could achieve alone, rather than the false goal of trying to replace humans with computers. Instead of beginning with the current state of the air transportation system, which could be appropriate for defining short-term goals, the development of long-term goals and visions should start by defining systemwide functional and performance requirements. The desired future state of the air transportation system, as one element of a multimodal national transportation system, should be defined using a comprehensive architecture that combines process elements for each dimension of the system (operational, system, technical, and economic). The future vision should also consider transitional issues: An environment that is conducive—in terms of regulations, regulatory approval processes, the certification process, operational procedures, and the perceptions of system operators, the traveling public, and society at large—to the introduction of new technologies and operational concepts. Interim improvements to the air transportation system along the way to the future. Incentives for government agencies and private industry to cooperate in defining and achieving a common vision. The vision should be dynamic, able to change over time as societal needs, global events, and advances in technology alter the perception of what is desirable and possible. Developing a comprehensive, unified vision for the future of the U.S. air transportation system—and generating widespread support to achieve the vision—will be a tremendous challenge. No single organization has responsibility for developing solutions that encompass the economic performance of private and governmental service providers, safety, security, environmental effects, and consumer satisfaction. Little is likely to happen without air transportation being clearly established as a national priority with strong, focused leadership. In fact, the committee believes that strong action by a federal agency or office to provide such leadership, with the broad support of the administration and the Congress, would do more to improve the ability of national aeronautical research and development programs to achieve their goals than any other change in the management or content of the programs themselves.5 Finding 1-3. Context for Future Requirements. Valid research requirements for the air transportation system depend on understanding how the U.S. air transportation system of the future will fit into both the national (intermodal) and international air transportation systems. Recommendation 1-2. National Vision. The process of improving the long-term performance of the air transportation system—and organizing a corresponding long-term research and technology program—should start with a unified, widely endorsed, national vision that specifies goals in each key area of interest to the commercial aviation community. The vision should establish goals related to safety and security, the capacity of the air transportation system, environmental compatibility (noise and emissions), the satisfaction of consumer needs, and industrial competitiveness. It should include a clear set of guiding principles and a strategy for overcoming transitional issues. Recommendation 1-3. Leadership. No single organization has the responsibility and authority for developing a comprehensive solution to the challenges faced by the U.S. air transportation system. Strong, focused leadership is needed. Federal leadership should be exercised by an agency or office with (1) the responsibility, authority, and financial resources necessary for defining air transportation system architectures through a centralized planning function, (2) an understanding of the interactions among system performance parameters, demand, and economic factors, such as the methods used to fund federal activities in support of the air transportation system, and (3) the credibility and objectivity to garner the active support of other air transportation stakeholders in government, industry, and the general public. This requires, among other things, a leadership group composed of individuals with a broad aviation perspective and a willingness to accept the risks of (1) looking ahead and (2) allowing others to help define the future. 5 Assessing the organization and role of specific government agencies was beyond the scope of this study (see Appendix A), so no recommendation is made as to which agency or office should be designated to provide the required leadership.
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Securing the Future of U.S. Air Transportation: A System in Peril REFERENCES Boeing. 2000. World Market Outlook. Seattle, Wash.: The Boeing Company. Commission on the Future of the U.S. Aerospace Industry. 2002. Final Report of the Commission on the Future of the U.S. Aerospace Industry. Washington, D.C.: U.S. Department of Commerce, International Trade Administration, Office of Aerospace. Available online at <www.aerospacecommission.gov/AeroCommissionFinalReport.pdf>. Dawson, L. 1968. Propulsion. Aeronautical Journal of the Royal Aeronautical Society 72:209–229. Federal Aviation Administration (FAA). 2003. FAA Aerospace Forecasts. Selected Aviation Demand Measures, Calendar Years 2003-2014, Table I-9. Washington, D.C.: FAA Office of Aviation Policy and Plans. Available online at <http://apo.faa.gov/foreca02/2003tab/exsumtableI-9.xls>. Federal Transportation Advisory Group. 2001. Vision 2050: An Integrated Transportation System. Washington, D.C.: Department of Commerce. Available online at <http://scitech.dot.gov/polplan/vision2050/index.html>. National Aeronautics and Space Administration (NASA). 2002. Aeronautics Blueprint. Washington, D.C.: NASA. Available online at <www.aerospace.nasa.gov/aero_blueprint/index.html>. National Research Council (NRC). 2002. For Greener Skies: Reducing Environmental Impacts of Aviation. Washington, D.C.: National Academy Press. Available online at <www.nap.edu/catalog/10353.html>. Neufville, R. 2000. Prospects for the future. Proceedings of the Airports in the 21st Century Conference, April 20, Washington, D.C. Transportation Research Circular Number E-C027. J.M. Rakas, G.W. Blomme, G. Gosling, eds. March 2001 (revised April 2001). Washington, D.C.: Transportation Research Board. pp. 90–113. Available online at <http://gulliver.trb.org/publications/circulars/ec027/ec027.pdf>. RTCA Free Flight Steering Committee. 2002. National Airspace System Concept of Operations and Vision for the Future of Aviation. Washington, D.C.: RTCA, Inc.
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