Research supported by the United States government has played an important role in the advancement of aeronautics and the U.S. aviation industry since the formation of the National Advisory Council for Aeronautics (NACA) in 1915. Government involvement in research has allowed industry to pursue concepts that would otherwise have been too highrisk, longterm, or expensive to research and develop. It has also encouraged the development of technologies that benefit society but do not offer manufacturers or users enough of an economic incentive for industry to sponsor the research itself. As a result, government research institutions like NACA and its successor, the National Aeronautics and Space Administration (NASA), have contributed greatly to both the welfare of society and the economic health of the aeronautics industry and, consequently, the country as a whole.

Although NACA and then NASA have always had to balance their aeronautics research efforts between nearterm projects that have a more immediate benefit for industry and longterm endeavors that help build the nation's technology base for future aircraft design, the organizations have always focused on finding pragmatic, technological solutions to the nation's aeronautical problems. The original NACA charter called for the agency to "supervise and direct the scientific study of the problems of flight, with a view to their practical solution." The mission statement of NASA's Langley Research Center, one of the main government facilities for aeronautics research since 1918, specifically calls for it to "perform innovative aerospace research relevant to national needs; transfer technology to users in a timely manner; and support U.S. government agencies, U.S. industry, NASA Centers, the educational community, and the local community." The mission statement also notes that "Our success will be measured by the extent to which our research results and technologies contribute to the design, development, and operation of future aerospace vehicles and missions."

By these standards, the research conducted with Langley's Boeing 737 Transport Systems Research Vehicle (TSRV), as part of the Terminal Configured Vehicle (TCV)/Advanced Transport Operating Systems (ATOPS) program, was extraordinarily successful. The program was created in 1973 specifically to research innovative technologies that could help solve some of the problems facing the national air transportation system. In the twenty years that followed, the airplane supported a wide variety of research projects with other NASA centers, the Federal Aviation Administration, the Department of Defense, industry manufacturers, and a number of universities. In addition, the transfer of technological information from the TCV/ATOPS program research was creative, timely and surprisingly effective, with the end result that the program and its research airplane had a significant impact on the development and application of a number of aeronautical technologies.

The TSRV 737 was instrumental in the development and acceptance of electronic flight displays for transport aircraft, which led to the creation of "glass cockpits." Its demonstrations of complex, curved path approaches using the Time Reference Scanning Beam (TRSB) microwave landing system (MLS) gave the U.S. candidate technology an unassailable edge in the international competition for a new instrument landing system. Years later, its research with global positioning system (GPS) approaches and autolands changed the nature of the entire debate about GPS and helped solidify the technology's position as a serious contender to be a partial or total replacement for MLS.

The windshear research conducted with the airplane led to the development of forwardlooking detection systems that gave airliners the ability to survive or avoid potentially lethal microbursts. The Digital Autonomous Terminal Access Communication (DATAC) data bus developed installed and tested on the TSRV 737 became the basis for a new national design standard for transport aircraft data bus systems. The Total Energy Control System (TECS) was incorporated into an unmanned, highaltitude, longrange reconnaissance vehicle by the Boeing Commercial Airplane Company. The electronic Engine Monitoring and Control System (EMACS) display format developed by a Langley engineer and flown on the 737 was adopted almost immediately by a general aviation avionics manufacturer and was included in the tentative cockpit design for the McDonnell Douglas Corporation's MDXX airliner.

Although the computerdriven, fuelefficient profile descents the NASA engineers evaluated with the TSRV 737 were not supported by the air traffic control (ATC) system, the NASA experiments proved the potential value of the technique, and the capability for timebased navigation eventually began to be implemented into some new airliners. The ATC data link experiments with the 737 gave the concept a critical measure of credibility and support, accelerating the acceptance and use of data link communication within the ATC system. The airplane also tested precision flare laws that helped Boeing engineers improve the autoland performance for several of Boeing's transport aircraft.

In addition, the TSRV 737 provided a highly capable testbed for numerous other successful research projects. The airplane helped conduct runway friction tests that proved the accuracy of ground friction measuring vehicles and the value of grooved runway and highway surfaces. As a result, airport operators gained access to reliable information about the safety of runway conditions, and the use of grooved surfaces increased at airports and on the nation's highways. A joint flight test project with McDonnell Douglas proved that a pilot could use a helmetmounted synthetic vision display to land a windowless transport aircraft. Because it was able to navigate successfully through a moving, metersquare spot in the sky, the TSRV 737 was able to obtain critical information for the United States Air Force. The airplane's flight research to model the instrument landing system (ILS) beam at the Los Angeles International airport gave the FAA valuable information about whether the runways could be spaced any closer together.

Although the airplane was still flying and conducting additional research 20 years after it was purchased by NASA, it had already had a tremendous impact on the "design, development and operation" of new aircraft. Achieving those results was neither simple nor easy, however. The world of aeronautics had changed dramatically from the early days of NACA, when a simple cowling design could revolutionize aircraft design and aircraft companies were clamoring to absorb whatever new knowledge or technology NACA could discover. The big problems facing the airlines in the 1970s were no longer ones of basic structures and aerodynamics. They were complex problems of getting aircraft to operate more efficiently and safely within an increasingly congested air traffic environment, and they required systemsoriented solutions.

Systems solutions are themselves complex, however. They typically need input from numerous research disciplines and involve many more elements and people. Systemsoriented research looks not only at individual aircraft components, but also the interactions between those components and the rest of the aircraft systems, the pilots, the operation of the aircraft within the ATC system, and the aircraft's compatibility with other air traffic in the vicinity.

The TCV program was created to research this kind of systemoriented technology, and the program organization reflected the complexity of the kind of research it set out to conduct. The matrix structure that caused so many management difficulties with the program was used precisely because the TCV research required input from numerous technical disciplines. The program also began with a joint agreement with the FAA and included an onsite contingent of Boeing engineers for the first five years. Few of its research projects, in fact, were conducted without the involvement of more than one research discipline, one or more other government agencies, or industry.

In addition to these kinds of challenges, the TCV/ATOPS program had to contend with the basic complexity of the technology development and transfer process. Both the selection of research projects and the eventual application of new technologies developed by the program were affected by political, social, economic and regulatory forces. The MLS demonstrations, for example, were initiated and then expanded because of the heated political controversy surrounding the international landing system decision. The windshear research was organized because of the political and social pressure following the 1985 crash of a Delta L1011 jumbo jet in Dallas Texas. The runway friction tests were funded after several airline accidents highlighted some of the dangers of winter flight operations. Even the basic funding for the TCV/ATOPS program itself fluctuated widely depending on the administrative and political pressures at play throughout its 20year history.

Forces that had little to do with the intrinsic worth of the concepts researched through the TCV/ATOPS program also had a tremendous impact on the eventual application of those technologies in commercial products. New ideas faced a human and organizational tendency to resist change, and as companies grew in size, effectively communicating information about new innovations to all the necessary players became more difficult. More importantly, however, the airline industry had changed dramatically since the days when pilots and aeronautical engineers ran the companies. As new technology became more expensive to produce and incorporate into aircraft designs, it had to "earn its way" onto airplanes more than it had in the past. In other words, technological innovations had to offer significant economic or other tangible benefits to be incorporated into new airliners; a trend that became even more pronounced after 1978, when deregulation made the airline industry more competitive and cost conscious.

Because pilots typically flew more than one aircraft, airlines also tried to keep cockpits of different aircraft relatively similar, both for safety and for training considerations. Dramatically new equipment could require retraining for all of an airline's pilots, not to mention recertification of an airplane design, both of which involved significant additional costs. As a result, even when new technologies were adopted, their full capabilities were often not used. The electronic attitude directional indicator (EADI) displays incorporated by Boeing in the 767/757s, for example, were formatted to duplicate an electromechanical instrument. Technologies such as MLS, profile descents or ATC data link communications faced even greater barriers to application, because they required changes in the ATC system, and airlines would not invest in equipment if the ATC system could not support its use.

In view of all this, the achievements of the TSRV 737 and the TCV/ATOPS program in researching, developing and transferring aeronautics technology are even more striking. There were several factors that enabled the program to have such an impact, however. First, the program was focused on solving problems that were both relevant and important to the air transport industry. Second, industry engineers were involved in the program from the very beginning, and the TCV/ATOPS research was characterized by a high level of communication between NASA engineers and industry representatives. As a result, the NASA researchers were more aware of industry concerns and problems, and they were able to obtain valuable feedback and suggestions about their research while it was still in process. Furthermore, the onsite involvement of a contingent of Boeing engineers for the first five years of the program and the numerous cooperative research efforts between NASA and industry in the years that followed allowed groups of industry engineers to become extremely knowledgeable about the technologies the NASA program was evaluating. Those engineers, in turn, played an important role in convincing other company decisionmakers to invest in further development and application of the concepts.

The most influential factor in the successful transfer of so many technologies from the TCV/ATOPS program to practical applications, however, was the TSRV 737 airplane. The unique Boeing aircraft, with its two cockpits, computerized and highly capable systems, and easily reconfigured research equipment, allowed a wide variety of new technologies to be flown in an actual transport class aircraft and often in realistic flight conditions. This capability was important, because as technology became more complex and expensive, industry became less able or willing to invest in innovations that had been tested only in laboratories or simulators. The gap between that level of development and a commercial application was often too broad, and the risks involved were too high. Research and demonstration flights, however, gave technology a level of credibility that no amount of laboratory or simulation testing could achieve and allowed researchers to demonstrate its potential capabilities and operational benefits in a vivid, visual manner to government and industry leaders. The impressive, curvedpath automatic landing demonstrations performed by the TSRV 737 airplane, for example, played a critical role in the selection of the U.S. candidate MLS system by the International Civil Aviation Organization (ICAO). Flight demonstrations of the electronic map display in the 737 helped convince airline operators to support the inclusion of a similar display in Boeing's new 767/757 aircraft.

Furthermore, a concept had to be developed further if it was going to be flight tested than if it was only going to be evaluated in simulations. Details and problems that wouldn't come into play in a laboratory had to be resolved before a technology would work on an airplane. Consequently, developing commercial applications for flight tested concepts entailed fewer risks for industry, which was an important consideration. Industry decisionmakers also had more confidence in a technological innovation that had been successfully flight tested. Boeing, for example, knew that the DATAC data bus worked in theory. What gave the company the confidence to include the technology in its next transport aircraft design, however, was the fact that the TSRV 737 had used DATAC without difficulty throughout hundreds of flight hours.

Most importantly, however, flight testing a new concept on the TSRV 737 provided essentially unassailable proof that the technology would work. The technique or innovation still might not prove economically viable, but a successful flight test ended the discussion about whether it could be done. The TSRV's research flights with pathinspace flare laws, for example, ended the engineers' debate about whether the theory was valid. And what made the airplane's GPSguided autoland flights so significant was not the technical performance of the system, but the fact that the airplane had actually completed automatic landings using GPS technology. The fact that the system still had to use a radar altimeter and the accuracy of the landings was not good enough for Category II or III certification standard was secondary. The NASA flight tests abruptly ended the debate about whether a GPS autoland was possible, and refocused the discussion and further research on what level of accuracy the technology could attain.

Of course, not all of the concepts flight tested with the TSRV 737 were picked up by industry or the FAA for practical application. Some did not prove viable, and logistical or economic issues overrode the technical worth of others. Nevertheless, the Boeing 737 TSRV proved immeasurably valuable in successfully researching and transferring advanced technologies and concepts from NASA to other government agencies and industry. It provided persuasive, visual evidence of a new technology's potential advantages and often gave decisionmakers the necessary confidence in experimental concepts to support the development of practical applications.

The value of NASA's 737 research airplane, however, went beyond its ability to transfer technology to industry. The airplane also had a significant influence on the Langley Research Center itself. The fact that the TCV/ATOPS program research included flight tests in a transport airplane kept its engineers focused on feasible technology and realworld air transportation problems. Since those researchers and engineers were drawn from various directorates around the center, that "realworld" anchor impacted attitudes throughout the facility. In addition, the Boeing 737 Transport Systems Research Vehicle provided the Langley center, already famous for its wind tunnels, with another kind of national research facility. The TSRV 737 offered government and industry a flexible, capable research platform that could test a wide variety of complex, systemsoriented technologies in a realistic flight environment. And as aeronautical problems became more complex, that kind of research facility was proving to be as important a national resource as the wind tunnels had been in the early days of flight.

Without question, NASA's Boeing 737 was a unique airplane. But the Terminal Configured Vehicle/Advanced Transport Operating Systems program was also a remarkable research effort. From the beginning, the TCV/ATOPS program involved complex relationships and organizational challenges, and both its research and the application of its findings were influenced heavily by political, business and economic factors. One of the managers who came to the TCV/ATOPS program from the Apollo space program concluded that the challenge of putting a man on the moon was relatively easy compared with trying to research and transfer technology to improve the air transportation system.

One of the reasons the program was able to succeed in spite of its complex internal and external challenges was because the people involved with the TSRV airplane and the TCV/ATOPS program were as unusual as the research effort itself. The program never even would have existed if it were not for the vision of the Langley engineers who saw the need for a systemsoriented, subsonic air transport research program and argued successfully for the purchase of the prototype Boeing 737100 airplane. Throughout its history, the engineers, researchers, and technicians who worked with the airplane and the program gained a reputation for having a enthusiastic, "can do" attitude that made many difficult research projects possible. The nature of the program attracted engineers who liked solving practical, realworld problems, and the resourcefulness and dedication of the technicians who worked on the plane was inspiring and contagious. Although it sometimes meant laboring all night in a freezing hangar to repair research systems, warming a computer component with a borrowed hair dryer, working by flashlights and generator power in order to finish a new data bus design, or pulling together a superhuman effort to repair and outfit the airplane in a few weeks instead of the months it should have taken, the people who worked with the TSRV 737 made sure that the plane successfully completed every single research project it was scheduled to conduct.

The reason the engineers, technicians and staff worked so hard on the TCV/ATOPS research projects was that they believed what they were doing was extremely important, not only to NASA, but to the aerospace industry and the country itself. They knew the research they did with the TSRV airplane was going to do more than generate technical reports. If they succeeded, their work could impact the landing system used around the world, revolutionize the information available to a new generation of airline pilots, and save lives.

In retrospect, the TCV/ATOPS program and the TSRV 737 did all of that and more. The prototype Boeing 737100 was originally purchased to support a single research program, which was expected to last only 56 years. Twenty years later, it was still performing an important role, not only for the TCV/ATOPS program, but for the Langley Research Center and the aerospace industry, as well. It had made significant contributions to the research and development of new aeronautical technologies that could help U.S. industry maintain a competitive edge in the global market, improve the operation of the national airspace system, and help save lives. The airplane might once have been an unwanted hulk on the ramp of the Boeing aircraft factory in Seattle, but the prototype 737100 had become a national asset. The stubby transport airplane was not as glamorous as NASA's Xseries research vehicles or as well known as the Space Shuttle, but the contributions it made were every bit as important.