2

Constraints

There are numerous complex constraints on the design and operation of the U.S. National Airspace System (NAS) to which the Federal Aviation Administration (FAA) and its stakeholders are subject. The FAA is well aware of these constraints—some of which may affect development of systems and some of which may bear on ultimate benefits and outcomes. In the committee’s view, it is helpful to keep these often challenging constraints, which include legacy commitments already made, in mind when planning, assessing, or evaluating Next Generation Air Transportation System (NextGen) efforts.

OPERATIONAL AND CAPACITY CONSTRAINTS

One of the goals for NextGen is to improve efficiency and reduce congestion in the NAS. FAA’s Aerospace forecast projects that the U.S. aviation industry will grow from 731 million passengers in 2011 to 1.2 billion in 2032.1 Congestion in the NAS tends to be localized to certain regions. Using 2012 FAA Air Traffic Activity Data for 21.7 million commercial air operations, more than 56 percent (12 million) of these involved the so-called Metroplex airports.2 Although there are opportunities to increase runway efficiency, such as less separation, parallel approaches, and so on, the realizable benefits of such are not yet clear. For example, wake vortex separation requirements may limit separation reduction, and local community resistance to noise and night flights may limit the introduction of new approach routes or extended hours that would increase the capacity of existing runways. In addition to all of this is uncertainty about what the future capacity needs will be given uncertainties about travel demand and fuel and other operational costs.

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1 FAA, FAA Aerospace Forecast: Fiscal Years 2012-2032, available at http://www.faa.gov/about/office_org/headquarters_offices/apl/aviation_forecasts/aerospace_forecasts/2012-2032/media/2012%20FAA%20Aerospace%20Forecast.pdf.

2 FAA, Air Traffic Activity Systems, Airport Operations, available at http://aspm.faa.gov/opsnet/sys/Airport.asp.



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2 Constraints There are numerous complex constraints on the design and operation of the U.S. National Airspace System (NAS) to which the Federal Aviation Administration (FAA) and its stakeholders are subject. The FAA is well aware of these constraints—some of which may affect development of systems and some of which may bear on ultimate benefits and outcomes. In the committee’s view, it is helpful to keep these often challenging constraints, which include legacy commitments already made, in mind when planning, assessing, or evaluating Next Generation Air Transporta- tion System (NextGen) efforts. Operational and Capacity Constraints One of the goals for NextGen is to improve efficiency and reduce congestion in the NAS. FAA’s Aerospace forecast projects that the U.S. aviation industry will grow from 731 million passengers in 2011 to 1.2 billion in 2032.1 Congestion in the NAS tends to be localized to certain regions. Using 2012 FAA Air Traffic Activity Data for 21.7 million commercial air operations, more than 56 percent (12 million) of these involved the so-called Metroplex airports. 2 Although there are opportunities to increase runway efficiency, such as less separation, parallel approaches, and so on, the realiz- able benefits of such are not yet clear. For example, wake vortex separation requirements may limit separation reduction, and local community resistance to noise and night flights may limit the introduction of new approach routes or extended hours that would increase the capacity of exist- ing runways. In addition to all of this is uncertainty about what the future capacity needs will be given uncertainties about travel demand and fuel and other operational costs. 1  FAA, FAA Aerospace Forecast: Fiscal Years 2012-2032, available at http://www.faa.gov/about/office_org/headquarters_ offices/apl/aviation_forecasts/aerospace_forecasts/2012-2032/media/2012%20FAA%20Aerospace%20Forecast.pdf. 2  FAA, Air Traffic Activity Systems, Airport Operations, available at http://aspm.faa.gov/opsnet/sys/Airport.asp. 6

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CONSTRAINTS 7 Political, Economic, and Cultural Constraints The NAS is a national infrastructure to which significant resources are devoted. As such, it has numerous stakeholders, and there are few individuals or businesses in the country that do not have an interest in or expectations regarding its performance. Thus, the NAS, the FAA, and NextGen efforts are subject to significant scrutiny—not only from users (such as trade groups, airlines, air- ports, and affiliated labor groups), but from Congress, other federal agencies, and the flying public as well. And as a federal agency, the FAA must operate within the federal political environment and under whatever financial and performance constraints and expectations are produced within it. External stakeholders, such as those listed above, have a variety of interests, demands, and constraints. Agreement, or at least rough consensus, on requirements will be important (albeit challenging to achieve). Some NextGen programs and components will undoubtedly have implica- tions for the workforce—controllers, safety specialists, and pilots. The capacity, skill sets, size, and expectations of the associated workforces will need to be taken into account when developing and deploying new or changed capabilities.3 NextGen’s benefits are expected to accrue to stakeholders; however, many of those benefits (such as increased automatic communication between aircraft) cannot be fully realized without participation and (sometimes costly) adoption by the relevant stakeholders.4 In addition, although many of the NextGen advances should benefit participants in the NAS writ large, the fact that some of the benefits may accrue to competitors could be a disincentive to participation by private entities. Thus, for some NextGen goals, the FAA is caught in a bind due to the distributed costs of deployment and the uncertainty of those costs if broad deployment does not occur. The expectation that economic benefits will sufficiently motivate airline equipment purchases may be misplaced, calling into question whether the anticipated voluntary uptake will occur. In addition to external political considerations, as a large organization, the FAA has its own organizational culture that has developed over time. The FAA and the United States rightly pride themselves on a devotion to safety and an excellent safety record to match. At the same time, a conservative safety culture can affect how quickly process and technological change can happen—a challenge in an arena where technologies change rapidly. An historic culture of safety and responsi- bility—especially one that has resulted in a strong safety record—may inhibit the adoption of new technologies or increased automation that could potentially result in net improvements in both safety and efficiency. Recognizing and taking into account the tensions among competing goals in an organization is critical to ensure progress. Technical Constraints The technical realities and constraints to which NextGen programs are subject run the gamut from the capabilities of legacy hardware to costs of certification to the challenges of large-scale system integration. The great majority of the tasks facing NextGen involve software and informa- tion and communications technology—the systems architecture has implications for how software 3  The 2007 National Research Council report Human-System Integration in the System Development Process: A New Look (The National Academies Press, Washington, D.C.) explores iterative development processes suitable for systems that have intensive human interaction and with humans having functional roles within the system (e.g., pilots, controllers, and so on.) 4  For example, ADS-B must be installed not only in larger commercial aircraft, but also in smaller general aviation aircraft to make full use of the system everywhere and there are costs (financial and also process) associated with deploying this technol- ogy. (Automatic dependent surveillance-broadcast (ADS-B) is an aircraft tracking technology that relies on the global positioning system (GPS) and a datalink to broadcast (ADS-B Out) and receive (ADS-B In) data.)

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8 INTERIM REPORT OF A REVIEW OF NEXTGEN components are developed and integrated and for how corresponding operational procedures are developed, refined, and deployed. Higher levels of software automation and integrity and fault tolerance will likely be needed, along with more reliable integration of aircraft and ground systems and processes. Future needs also include more flexibility and agility in systems and processes to deal with a dynamic and uncertain environment coupled with, wherever possible, reduction of uncertainties in the system (e.g., improved weather forecasting, tracking of wake vortices, wind shear, and so on). Avionics systems and any upgrades or changes to them require time and resources for certi- fication and, ultimately, integration. In addition, most avionics systems must have international backing and agreement in order to achieve substantial deployment, so rapid introduction of new technologies that might benefit the national airspace may not be possible. For certain capabilities, decisions will need to be made about whether to deploy new software or whether software emulators running on new hardware may be sufficient. 5 In addition, as capa- bilities are developed and deployed, ensuring that potential avenues of future improvement—such as in the areas of communications, authentication, and spectrum management—are not closed off prematurely will be important. Aligning operational procedures with revised or enhanced technological capabilities is critical to the success of any technology advances. Ensuring clear processes and plans for any changes to the operational infrastructure, such as the development of procedures and airspace that take full advantage of the new technical capabilities of NextGen, will be important. Given the human- intensive nature of operating the national airspace, there are also challenges related to design for organizations and to human-system integration, including robustness of the combined human- machine interaction, along with human factors concerns with the implementation of new techni- cal functions. The anticipated benefits of NextGen will depend on commensurate changes in the airspace and how all of these challenges are managed. The bulk of NextGen software and system development is done under a variety of contracts, thus obliging the FAA (or another contractor) to act as the system integrator. The structure of the network of supplier relationships and incentives to create and deploy NextGen will bear on devel- opment and deployment. A systems architecture serves as an integration blueprint that demands careful specification of the behaviors and interfaces of the components, effective tracking of con- tractor efforts, and continuous integration and testing of in-progress and completed components. Moreover, the importance of human-systems interaction and human factors in NextGen has impli- cations for how the work is contracted. Notably, it is challenging to make measureable, quantifiable specifications for human factors—such as ensuring that the contractor makes a product that is truly effective and usable from the point of view of the controller. Thus, delegation of detailed design to contractors has implications for these and related aspects of NextGen. More generally, in the management of architecture, there is a natural tension between the client (FAA) and the supplier (various contractors) with regard to architecture leadership. Architectural leadership also requires senior management attention to constraints, incentives, and design participation by suppliers. Inef- fective leadership can result in a diffusion of responsibility, which can result in perverse incentives for suppliers. Diffusion of responsibility might also lead to a vague, ineffective architecture or to different interpretations by different actors (client, various vendors).  If the architecture leadership is weak or dispersed, it could lead to an overall system with no architecture or a flawed architecture.   5  Similar efforts were undertaken in the late 1990s for the FAA’s Host Computer System. See FAA, Host and Oceanic Computer System Replacement Program, available at http://www.faa.gov/news/press_releases/news_story.cfm?newsId=6419, 1999.