The pending debate over reauthorization of the Federal Aviation Administration (FAA) is likely to be a high priority in the 110 th Congress. Funding authorizations for aviation programs set forth in Vision 100—the Century of Aviation Reauthorization Act ( P.L. 108-176 , hereafter referred to as Vision 100), as well as authorization of the existing aviation tax structure that provides revenue for the aviation trust fund, are set to expire at the end of FY2007. CRS has identified nine broad categories of issues that Congress may address in the context of FAA reauthorization. These include FAA budgeting and finance; airport development and finance; FAA cost control measures; system-wide demand and capacity issues; modernization of national airspace system (NAS) infrastructure; aviation safety; airliner cabin issues; energy, environment, and noise issues; and international civil aviation issues. Authorization of the existing aviation tax structure that provides revenue for the aviation trust fund will expire at the end of FY2007. While such tax authorizations have expired in the past, the current deliberations over FAA funding are considered particularly critical. This, in part, is because uncommitted balances in the airport and airways trust fund (AATF), commonly referred to as the aviation trust fund, have declined in recent years, leaving a relatively small reserve to pay for aviation programs in the event that tax collection authorities are allowed to expire. Also, major initiatives to develop and deploy the Next Generation Air Transportation System (NGATS) by 2025, initiated during the last reauthorization process, are reaching a stage where they will require additional funding resources if these plans are to be realized. While no official projections are yet available on the total cost for NGATS, early estimates indicate that it will require an average of $200 million to $1 billion annually in facilities and equipment costs over the next several years to keep NGATS development initiatives on track. Congress may consider a variety of financing options to maintain the ability of the aviation trust fund to provide a sufficient revenue stream for ongoing operational costs and planned infrastructure improvements, in the near-term and to support the long-term NGATS development efforts. In the course of this debate, Congress may consider the appropriate cost allocation between aviation system users, the share of the cost burden to be borne by the aviation trust fund, and the share to be derived from Treasury general funds (the so-called public interest contribution). The relative tax burden placed on various industry participants has been a source of controversy for over 36 years, since the aviation trust fund was created. The airlines argue that they have been paying a disproportionately larger share of the system costs compared to general aviation users since the largest revenue sources for the aviation trust fund are derived from passenger ticket taxes. The airlines claim that in their highly competitive industry, they must absorb some of the tax-related costs in their fare pricing schemes. The airlines have identified general aviation users, and business jet operators in particular, as a segment of the aviation economy that, in their opinion, is not paying its fair share of the costs to maintain and improve the national airspace system (NAS). General aviation users argue, on the other hand, that the NAS has largely been developed to support the airline industry, that the incremental costs to accommodate general aviation users is not that large, and that existing fuel taxes are sufficient to compensate for their impact on the system. One alternative to the existing tax structure supported by the airlines is a fee-for-service system that would be more of a direct user fee system than what is in place now. Some industry observers claim that the FAA has been mulling the idea of a direct user fee structure to replace existing aviation taxes and fees, and an administration proposal has reportedly been under review by the Office of Management and Budget (OMB) for some time. While the details of the proposal are unknown, speculation is that it will conform more closely to international standards that stipulate user fees be computed as some function of the specific impact on air traffic facilities and services, such as the commonly used fees based on aircraft weight and distance flown used by many nations. During the reauthorization debate, Congress may consider a variety of aviation trust fund revenue alternatives that may include keeping the existing passenger ticket and fuel taxes largely or completely intact, moving to a tax revenue scheme based solely on fuel taxes, adopting a user fee-based system, or developing a hybrid scheme that consists of some combination of these alternatives. One hybrid approach that has been discussed is to charge user fees for airlines and operators of larger general aviation aircraft, while small general aviation users would continue to contribute solely by means of a fuel tax, although these fuel tax rates and structure could differ from what currently exists. The Airport Improvement Program (AIP) provides federal grants for airport development. Its funding is derived from the airport and airways trust fund, and it is one of five major sources of funding for airport development and improvement. Airports also fund capital projects using tax-exempt bonds, passenger facility charges (PFCs; a local tax levied on each boarding passenger), state and local grants, and airport revenue. The preeminent reauthorization issue for AIP is whether its funding levels will be increased substantially, held steady/increased modestly, or reduced. The outlook for AIP funding will be influenced by the resolution of the debate concerning taxes and fees supporting the aviation trust fund as well as any decision concerning the scope of the general fund share of the FAA budget. A failure to secure more revenue for the FAA budget, in light of the recent decline in the uncommitted balance of the trust fund, could constrain any attempts to increase the AIP budget. During the reauthorization process, Congress may also examine a wide variety of other issues pertaining to the AIP program including airport eligibility and apportionments among various sizes of airports; discretionary funding levels and uses of discretionary grants; the scope of grant assurances to protect federal interests in airport projects; funding levels set aside for noise-related projects; the appropriate federal share of funding for airport projects at airports of various sizes; possible expansion of or modification to the airport privatization pilot program; partial defederalization of airport funding allowing airports to use PFCs instead of AIP as a primary or sole source for project funds; limitations on the use of AIP funds for airport security projects; the possible impacts of accommodating new users classes such as very light jets (VLJs) and the Airbus A380 super-jumbo jet on airport infrastructure needs and airport financing; and the use of earmarks or "place naming" in legislation regarding airport infrastructure projects. In addition to AIP funding and related issues, Congress may consider options to raise the cap on PFC levels to provide additional funding availability outside of AIP, and options to make airport bonds more attractive to investors, although some may argue the latter may be more appropriately addressed through tax reform legislation rather than FAA reauthorization. Besides consideration of a revenue system for funding the aviation trust fund, controlling the costs of operating and maintaining the existing national airspace system has been an ongoing concern for the FAA and for congressional oversight. Cost control measures may be a particular issue of interest during the FAA reauthorization debate as Congress grapples with the prospect of escalating operational costs that must be balanced with the fiscal needs to support planned infrastructure development, both over the near-term to fund ongoing and planned system expansion and over the long-term to support the NGATS development. Outsourcing has been seen as a viable alternative for controlling costs in some instances, such as the FAA's federal contract tower (FCT) program and the recently privatized automated flight service stations (AFSSs). Expanded outsourcing of various FAA functions, such as further expansion of the contract tower program and privatization of the FAA's aeronautical charting functions, are possible options that both the FAA and Congress may examine. Also, the FAA and Congress may look to increase the use of designees to carry out certain aviation oversight functions. However, some critics argue that these outsourcing options are likely to yield relatively small cost savings in comparison to the overall FAA operations budget. Further, these options are likely to be highly contentious and face strong opposition from labor organizations. Whether these outsourcing measures potentially compromise safety in any way remains a specific point of contention. While some have advocated large scale privatization of air traffic services—as has been done in Canada, Australia, the United Kingdom, and parts of mainland Europe—this approach would be highly complex to carry out, and this option has failed to garner much support in Congress. The current administration has indicated previously that is has no plans to privatize en route and terminal air traffic control facilities, but may opt to expand the contract tower program. Consolidation of facilities and functions has also been viewed as a possible way to control operational costs at the FAA. The FAA is currently in the process of consolidating administration and support functions in its regional service areas, and has plans to consolidate weather services provided at en route centers. Also, under the privatized AFSS program, an extensive consolidation of flight service facilities is currently in process. Some have proposed that the FAA implement a systematic process, perhaps using something akin to the military's Base Realignment and Closure (BRAC) process, to address future consolidation plans for facilities and functions. Congress may debate the merits of this proposal during the pending FAA reauthorization. In the long term, under NGATS, consolidation of air traffic services and air traffic facilities may be possible. With increased reliance on automation and by increasing the autonomy, flexibility, and authority granted to individual flights operating in the national airspace system (NAS), the ratio of air traffic controllers to aircraft operating in the system is likely to drop. In the near term, this will likely be offset by the growth in air traffic operations, so that a modest increase in the overall number of air traffic controllers is expected.