FAA’s mission is to provide a safe and efficient airspace system. As part of this mission, the agency uses airport system planning to better understand the interrelationship of airports at the national, state, and regional levels. FAA guidance states that the overall goals of airport system planning are to ensure that the air transportation needs of a state or metropolitan area are adequately served by its airports, and that planning results in products that can be used by the planning organization, airports, and FAA to determine future airport development needs. There are several types and levels of planning involving individual airports or airport systems, including the National Plan of Integrated Airport Systems (NPIAS), state and regional system plans, and airport-level plans. The NPIAS identifies over 3,400 airports as being nationally significant to the national airspace system, including all of the nation’s commercial service and reliever airports and some general aviation airports. Most states periodically develop state airport system plans to inventory airports using a set of criteria developed by FAA. While not required, some regions choose to carry out regional airport planning—which may include the development of regional airport system plans (RASP) or other regional airport plans—to identify critical regional airport issues and to integrate aviation with other modes in a region’s transportation system. At the airport level, two types of plans support airport improvements at individual airports, the airport layout plan (ALP), which is required for federal funding, and the airport master plan. Figure 1 provides additional information about these plans and illustrates the role of each in the FAA in the FAA funding process for airport improvement projects in the AIP. funding process for airport improvement projects in the AIP. Airports in the NPIAS become eligible to apply for FAA’s AIP grants, which provided almost $3.5 billion for capital projects in fiscal year 2008. AIP funding is available for eligible projects, which include projects such as airfield construction or equipment purchases, terminal or terminal access improvements, land acquisition, noise compatibility projects, and regional airport planning. AIP grants generally consist of two types— entitlement funds that are apportioned to airports or states by formula each year based upon statutory criteria, and discretionary funds that FAA approves based on a project's priority. To ensure that the highest priorityprojects nationally are funded, discretionary funds are awarded using a national priority rating system that awards points on a variety of factors including airport size; the purpose of the project (e.g., capacity related, planning, environmental, and safety); and the type of project (e.g., termi improvement and equipment purchase). Airports apply directly to FAA through FAA regional offices for AIP discretionary funding, an projects are scored using the national priority rating system. Furthermore, the Airport and Airway Improvement Act of 1982 (AAIA)— which established the current AIP—provided FAA with the authority to give priority to airport improvement projects that are consistent with integrated airport system plans, such as RASPs. In the guidance provided by FAA for airport system planning, airport sponsors are also encourage d to use findings and recommendations from regional airport plannin develop plans to serve as a guideline for the allocation of funding. While no specific amount is currently set aside for system planning in the AIP program, approximately 2 percent of funds made available annually for AIP grants since 1970 have been used for these purposes. Most of this funding is used for planning at the state or airport level, but some re gions have also applied for and received AIP funding for regional airport planning. This funding has been used for a variety of planning efforts by states, airport sponsors, and regional planning bodies—primarily MPOs— and includes the development of RASPs. Other regional airport planning funded with AIP grants includes special studies to analyze or address new or unique issues, such as compatible land uses around airports, zoning implementation, or airport ground access. There are a number of stakeholders with interests in the airport planning process. They include FAA, states, and airports and may also include MPOs, airlines, and local communities. The FAA’s Office of Airport Planning and Programming provides guidance about airport system planning, while FAA regional offices administer grants and provide technical support to airports and others developing airport plans at the airport, regional, and state levels. The range of involvement by a particular stakeholder group varies by the type of plan under development, among other things. Thus, FAA, airports, and sometimes airlines are typically most involved in the development of ALPs and airport master plans and the resulting capital plans. States work with airports—notably, general aviation or reliever airports, not typically major commercial airports—to identify airports and improvements for inclusion in state airport system plans. MPOs may work with airport sponsors, local jurisdictions, state authorities, and FAA when developing RASPs or carrying out other regional airport planning. FAA accepts plans developed by states or MPOs and reviews and approves ALPs. In addition to federal and state aviation officials, other stakeholders in the process include the following: Airport sponsors: Airport sponsors can be any one of a number of different types of public entities, such as cities, counties, airport authorities, ports, intermodal agencies, or private owners. MPOs: MPOs may lead or participate in regional airport planning, but their primary role is carrying out regional surface transportation planning in urbanized areas, including the development of long-range and short-range transportation plans. To receive federal surface transportation funding, any project in an urbanized area must emerge from the relevant MPO and state department of transportation planning process. Airlines: Airlines play a key role in the functioning of airport systems, since they make decisions about which airports to serve and how frequently to provide service. Airlines may consider a number of factors in making these decisions, such as the location of regional business, economic indicators, the travel patterns of area residents, the cost of establishing service at particular airports, the effects on their service network, and the service provided by competing carriers. FAA guidance on airport system planning identifies eight key elements of the planning process, including inventorying the airport system, identifying air transportation needs, considering alternative airport systems, and preparing an implementation plan (see table 1). The guidance states that the end result should be “the establishment of a viable, balanced, and integrated system of airports to meet current and future demand.” FAA does not approve airport master plans, state airport system plans, or RASPs. For those plans developed with FAA funding, however, FAA is involved in developing the scope of work covered under the grant, reviewing draft documents, approving aviation forecasts, and then accepting the final plan. When considering alternative airport systems (the fifth of the eight elements), regional planners may identify alternate, underutilized airports in a region as having the potential to relieve pressure on congested airports. FAA’s airport system planning guidance states that the development of such alternate airports should only be undertaken when a full assessment has been done of various market factors. The guidance states that it is important to understand the nature of demand within a region, including factors that would divert demand to other airports, and any potential political, economic, or institutional barriers to developing an airport system. It also recommends that planners assess the ability of the airport to offer adequate service—in terms of convenience, schedules, and fares—and the effect on airlines, noting that the development of alternate airports should enhance airline profitability and be compatible with their route systems. In addition to the development of RASPs, other types of regional airport planning, including special studies whose scope of work does not fully correspond with the elements described in the airport system planning guidance, may be undertaken with AIP grants, according to FAA’s airport system planning guidance. Special studies can include but are not limited to work in such areas as air service, air cargo operations, environmental or drainage inventories, surface access, economic impact, obstruction analysis or photogrammetry, general aviation security, and pavement management. FAA’s airport system planning guidance states that MPOs can receive FAA support to conduct regional airport planning in areas that include large- or medium-hub airports (1) when such agencies have the interest in and capabilities to conduct such planning and (2) when regional FAA, state aviation, and local airport officials determine that MPOs should have a role. The guidance continues that the regional airport planning carried out by MPOs should complement—rather than guide—the planning done by FAA, states, and individual airports. According to the guidance, MPO-led regional airport planning may enhance the integration of the entire regional transportation system by promoting aviation enhancement and preservation, identifying critical regional aviation issues, and acting as the contact point for regional surface access, air quality, and land-use planning studies. MPOs can also act as a catalyst in implementing system planning recommendations—which may involve several stakeholders—by resolving local conflicts, promoting airport development funding priorities, and proposing the distribution of grants among eligible projects. The guidance states that an MPO’s ability to implement regional airport planning recommendations is limited to the extent that it can influence airport development through persuasion; leadership; or nonaviation incentives, such as surface transportation improvements that may improve airport access. This stands in contrast to state aviation agencies, which can implement system planning recommendations using legislative and funding mechanisms, including AIP funds, whereas MPOs do not receive AIP funds, other than for planning purposes. FAA’s FACT 2 report forecast that 14 airports will be significantly capacity constrained—and thus potentially congested—by 2025, even if currently planned improvements are carried out. According to FAA, some airports are already significantly capacity constrained, and increased demand is expected to increase delays going forward. Six of these 14 airports will be significantly capacity constrained as early as 2015, according to the report. (See fig. 2.) The FACT 2 study was designed to produce a conservative list of congested airports, according to FAA officials, and identified those airports that will have the greatest need for future additional capacity.