The Budget Control Act of 2011 ( P.L. 112-25 ) provided for automatic reductions to most federal discretionary spending if no agreement on deficit reduction was reached by the Joint Select Committee on Deficit Reduction. Such reductions, referred to as sequestration, went into effect on March 1, 2013, the extended deadline for a deficit reduction agreement established under the American Taxpayer Relief Act of 2012 ( P.L. 112-240 ). In general, sequestration required agencies to reduce non-defense discretionary spending by 5.3% in FY2013. Sequestration affects Federal Aviation Administration (FAA) operations in different ways. FAA's grants for airport improvements, which are subject to obligation limitations, were statutorily exempt from the sequester cuts. On the other hand, FAA's air traffic operations face significant spending reductions. In total, it is estimated that FAA will need to reduce its total funding by roughly $636 million in FY2013 compared to FY2012 enacted levels, with roughly three-quarters of this amount coming from FAA operations, primarily air traffic and aviation safety functions. In anticipation of the sequester cuts, Transportation Secretary Ray LaHood and FAA Administrator Michael Huerta issued a joint letter on February 22, 2013, announcing cost-cutting measures under consideration including furloughs for most FAA employees, elimination of late-night shifts in as many as 72 air traffic control facilities, and the complete closure of up to 238 control towers at airports that have fewer than 150,000 flight operations or fewer than 10,000 commercial operations per year. Towers listed as candidates for closure included 195 run by contractors under the Federal Contract Tower (FCT) program and 43 staffed by FAA controllers. On March 22, 2013, FAA announced it would close 149 FCT program towers over four weeks beginning April 7, 2013. FAA said it chose to keep open 24 FCT facilities initially identified for closure after weighing national security interests; adverse economic impacts beyond the local community; potentially significant impacts on interstate transportation, communication, or banking and financial networks; and status as a critical diversionary airport for a large hub airport. On April 5, 2013, citing a need for additional time to address multiple legal challenges to its tower closure decisions, FAA delayed the closures and set June 15, 2013, as the date it would cease funding the 149 FCT program towers. Several airports have filed suit against FAA, chiefly questioning whether it has adequately met legal obligations to evaluate potential safety risks associated with the pending tower closures. On May 1, 2013, following a week of FAA air traffic controller furloughs that contributed to some isolated air traffic system delays, particularly at the nation's busiest airports, the Reducing Flight Delays Act of 2013 ( P.L. 113-9 ) was enacted. The act gave FAA authority to transfer up to $253 million to FAA operations using available monies from unspent airport funds, which were not subject to sequestration, and from other available sources within FAA. On May 2, 2013, a bipartisan group of 25 Senators transmitted a letter to Secretary of Transportation Ray LaHood and FAA Administrator Michael Huerta. The letter indicated that the $253 million transfer authority was "far above the amount required to prevent furloughs," stressing further that "[c]ongressional intent is clear: the FAA should prevent the slated closure of 149 contract towers by fully funding the contract tower program." On May 10, 2013, Secretary LaHood announced that the funds transfer authority under P.L. 113-9 was sufficient to end FAA employee furloughs and keep the 149 towers open for the remainder of FY2013. While this action appears to have settled debate over the pending closure of control towers in FY2013, long-range plans for tower closures, cutbacks in operating hours, or both may be revisited in future policy debates regarding the FAA budget. The financing and continued operation of low-activity towers, in particular, remain significant issues for future FAA budgets. In general, the funding and operation of civil air traffic control towers in the United States and U.S. territories fall into one of four categories: (1) tower operations funded through FAA's operations budget and staffed with federal air traffic controllers; (2) contract tower operations fully funded through FAA's operations budget but staffed with controllers employed by the contractor under the federal contract tower (FCT) program (also known as the contract tower base program); (3) contract tower operations partially funded through the FAA's operations budget and partially funded by local or state government funding and managed and staffed by contractor personnel, referred to as the contract tower cost-share program; and (4) non-federal control towers that receive no funding from the federal government and are staffed with non-federal controllers. Regardless of funding and operation, FAA maintains responsibility for the regulation and oversight of operations and safety at all civil air traffic control towers in the United States. Contract towers and contract controllers must be certified by FAA and must follow FAA directives. FAA funds for tower operations are derived from appropriations to the FAA's Operations and Maintenance (O&M) account, which is funded partially from the Airport and Airways Trust Fund (AATF) and partially from the Treasury general fund. These sources provide funding for both the contract tower program and FAA-staffed towers. Of U.S. airports with control towers, 251 (slightly less than half) are operated by private firms and staffed with contract employees under the FCT program. Sixteen of the 251 contract towers are funded under arrangements in which local governments or entities pay up to 20% of the costs. The cost-share program is provided as an option to communities that wish to retain an operating air traffic control tower after FAA determines that the costs to the federal government outweigh their tower's benefits related to safety and efficiency of flight operations. With the exception of these 16 cost-share towers, towers in the federal contract tower program are fully funded by FAA. In recent years, the budget for the FCT program has been about $140 million annually, including approximately $10 million for the federal share of cost-share towers. The FCT program came into existence in 1982—initially as a pilot program at five airports—in an effort to provide air traffic services at low-activity towers in the wake of the nationwide air traffic controller strike and subsequent dismissal of striking FAA controllers. For the first 12 years, the program remained relatively small, growing to 27 towers by 1993. Nonetheless, it gained the attention of Vice President Gore's National Performance Review—later known as the National Partnership for Reinventing Government—which endorsed the program in 1993 and recommended its expansion. The FAA developed a plan to close or contract out all low-activity towers, and the number of contract towers grew to 160 by the end of FY1997. In FY1999, Congress first funded the cost-sharing program, allowing airports that would not otherwise have met FAA's threshold benefit-to-cost ratio to maintain contract tower operations with non-federal funds to supplement federal expenditures. Subsequently, Congress has limited the local share to not more than 20% of a tower's costs. Currently 16 towers are funded through this program at a cost of roughly $10 million annually. The federal funding for cost-share towers has been designated separately in recent appropriations measures, and therefore is not included in the proposed funding cuts and tower closures being considered in FY2013. However, FAA has indicated that it would seek to increase the local share portion of the cost-share program in FY2014 from 20% to 50%. While this could expand program eligibility, it could also have the effect of triggering tower closures in communities that are unwilling or unable to contribute additional funding for tower operations. In a 2012 audit, the Department of Transportation Office of Inspector General concluded that the FCT program provided air traffic services to low-activity airports at lower costs than FAA-staffed towers could. The audit found that, on average, contract towers required six fewer controllers and cost almost $1.5 million less annually than FAA-staffed towers at airports with comparable levels of flight activity. These savings were achieved through lower staffing levels and lower controller pay at contract towers compared to FAA towers. The audit found that contract towers had a lower rate of reported safety incidents than comparable FAA towers. Also, a survey of aircraft operators, conducted as part of the audit, found similar levels of satisfaction with the services provided by contract towers and FAA towers handling similar numbers of aircraft. The FAA operates 262 airport air traffic control towers. About one-quarter of these are similar in activity levels to contract towers. These have remained under FAA operation primarily because of local operational considerations, such as proximity to congested airspace, or are considered candidates for conversion to the FCT program, but have not yet been converted. Of the FAA-operated towers, 43 have been identified as having fewer than 150,000 total operations or fewer than 10,000 commercial operations annually and have been included on the list of potential tower closures. Additionally, several FAA-staffed towers at mid-sized airports had been identified as facilities where late-night shifts could be eliminated in FY2013. Several of the towers listed have radar approach capabilities. However, these towers typically see limited late-night activity, comprising mainly all-cargo operations with occasional general aviation traffic. Examples include the towers at Little Rock, AK; Manchester, NH; Oklahoma City, OK; Harrisburg, PA; Reno, NV; El Paso, TX; and Norfolk, VA. Many other towers, including both FAA-operated and contract towers, already close during late-night hours. When a tower closes, either overnight or permanently, the airport will typically remain open to traffic as an uncontrolled airport. In some rare instances, an uncontrolled airport may close late at night for noise abatement or due to safety concerns in mountainous areas, but runway lights and other navigational aids remain functional so it could serve as an emergency landing site for an aircraft in distress.