opinion: CITY OF BURBANK et al. v. LOCKHEED AIR TERMINAL, INC., et al.
  No. 71-1637.
  Argued February 20,1973
  Decided May 14,1973
  Douglas, J., delivered the opinion of the Court, in which Burger, C. J., and Brennan, Blackmun, and Powell, JJ., joined. Rehnquist, J., filed a dissenting opinion, in which Stewart, White, and Marshall, JJ., joined, post, p. 640.
  Richard L. Sieg, Jr., argued the cause for appellants. With him on the briefs was Samuel Gorlick.
  Warren Christopher argued the cause for appellees. With him on the briefs was Ralph W. Dau.
  Deputy Solicitor General Friedman argued the cause for the United States as amicus curiae urging reversal. On the brief were Solicitor General Griswold, Assistant Attorney General Wood, Andrew L. Frey, and John W. Barnum. Nicholas C. Yost, Deputy Attorney General, argued the cause for the Attorney General of California as amicus curiae urging reversal. With him on the brief were Evelle J. Younger, Attorney General, pro se-, Jay L. Shavelson, Assistant Attorney General, and Larry C. King, Deputy Attorney General.
  Briefs of amici curiae urging affirmance were filed by Patrick J. Falvey, Joseph Lesser, Isobel E. Muirhead, and Vigdor D. Bernstein for the Port Authority of New York and New Jersey; by Robert D. Powell for the National Business Aircraft Association, Inc.; and by Samuel J. Cohen for the Air Line Pilots Association, International.
  Mr. Justice Douglas
  delivered the opinion of the Court.
  The Court in Cooley v. Board of Wardens, 12 How. 299, first stated the rule of pre-emption which is the critical issue in the present case. Speaking through Mr. Justice Curtis, it said:
  “Now the power to regulate commerce, embraces a vast field, containing not only many, but exceedingly various subjects, quite unlike in their nature; some imperatively demanding a single uniform rule, operating equally on the commerce of the United States in every port; and some, like the subject now in question, as imperatively demanding that diversity, which alone can meet the local necessities of navigation.
  “. . . Whatever subjects of this power are in their nature national, or admit only of one uniform system, or plan of regulation, may justly be said to be of such a nature as to require exclusive legislation by Congress.” Id., at 319.
  This suit brought by appellees asked for an injunction against the enforcement of an ordinance adopted by the City Council of Burbank, California, which made it unlawful for a so-called pure jet aircraft to take off from the Hollywood-Burbank Airport between 11 p. m. of one day and 7 a. m. the next day, and making'it unlawful for the operator of that airport to allow any such aircraft to take off from that airport during such periods. The only regularly scheduled flight affected by the ordinance was an intrastate flight of Pacific Southwest Airlines originating in Oakland, California, and departing from Hollywood-Burbank Airport for San Diego every Sunday night at 11:30.
  The District Court found the ordinance to be unconstitutional on both Supremacy Clause and Commerce Clause grounds. 318 F. Supp. 914. The Court of Appeals affirmed on the grounds of the Supremacy Clause both as respects pre-emption and as respects conflict. 457 F. 2d 667. The case is here on appeal. 28 U. S. C. § 1254 (2). We noted probable jurisdiction. 409 U. S. .840. We affirm the Court of Appeals.
  The Federal Aviation Act of 1958, 72 Stat. 731, 49 U. S. C. § 1301 et seq., as amended by the Noise Control Act of 1972, 86 Stat. 1234, and the regulations under it, 14 CFR pts. 71, 73, 75, 77, 91, 93, 95, 97, are central to the question of pre-emption.
  Section 1108 (a) of the Federal Aviation Act, 49 U. S. C. § 1508 (a), provides in part, “The United States of America is declared to possess and exercise complete and exclusive national sovereignty in the airspace of the United States . . . .” By §§ 307 (a), (c) of the Act, 49 U. S. C. §§ 1348 (a), (c), the Administrator of the Federal Aviation Administration (FAA) has been given broad authority to regulate the use of the navigable airspace, “in order to insure the safety of aircraft and the efficient utilization of such airspace . . and “for the protection of persons and property on the ground .
  The Solicitor General, though arguing against preemption, concedes that as respects “airspace management” there is pre-emption. That, however, is a fatal concession, for as the District Court found: “The imposition of curfew ordinances on a nationwide basis would result in a bunching of flights in those hours immediately preceding the curfew. This bunching of flights during these hours would have the twofold effect of increasing an already serious congestion problem and actually increasing, rather than relieving, the noise problem by increasing flights in the period of greatest annoyance to surrounding communities. Such a result is totally inconsistent with the objectives of the federal statutory and regulatory scheme.” It also found “[t]he imposition of curfew ordinances on a nationwide basis would cause a serious loss of efficiency in the use of the navigable airspace.”
  Curfews such as Burbank has imposed would, according to the testimony at the trial and the District Court’s findings, increase congestion, cause a loss of efficiency, and aggravate the noise problem. FAA has occasionally enforced curfews. See Virginians for Dulles v. Volpe, 344 F. Supp. 573. But the record shows that FAA has consistently opposed curfews, unless managed by it, in the interests of its management of the “navigable airspace.”
  As stated by Judge Dooling in American Airlines v. Hempstead, 272 F. Supp. 226, 230, aff’d, 398 F. 2d 369:
  “The aircraft and its noise are indivisible; the noise of the aircraft extends outward from it with the same inseparability as its wings and tail assembly; to exclude the aircraft noise from the Town is to exclude the aircraft; to set a ground level decibel limit for the aircraft is directly to exclude it from the lower air that it cannot use without exceeding the decibel limit.”
  The Noise Control Act of 1972, which was approved October 27, 1972, provides that the Administrator “after consultation with appropriate Federal, State, and local agencies and interested persons” shall conduct a study of various facets of the aircraft noise problems and report to the Congress within nine months, i. e., by July 1973. The 1972 Act, by amending § 611 of the Federal Aviation Act, also involves the Environmental Protection Agency (EPA) in the comprehensive scheme of federal control of the aircraft noise problem. Under the amended § 611 (b)(1), 86 Stat. 1239, 49 U. S. C. § 1431 (b) (1) (1970 ed., Supp. II), FAA, after consulting with EPA, shall provide “for the control and abatement of aircraft noise and sonic boom, including the application of such standards and regulations in the issuance, amendment, modification, suspension, or revocation of any certificate authorized by this title.”' Section 611 (b)(2), as amended, 86 Stat. 1239, 49 U. S. C. § 1431 (b) (2) (1970 ed., Supp. II), provides that future certificates for aircraft operations shall not issue unless the new aircraft noise requirements are met. Section 611 (c)(1), as amended, provides that not later than July 1973 EPA shall submit to FAA proposed regulations to provide such “control and abatement of aircraft noise and sonic boom” as EPA determines is “necessary to protect the public health and welfare.” FAA is directed within 30 days to publish the proposed regulations in a notice of proposed rulemaking. Within 60 days after that publication, FAA is directed to commence a public hearing on the proposed rules. Section 611 (c)(1). That subsection goes on to provide that within “a reasonable time after the conclusion of such hearing and after consultation with EPA,” FAA is directed either to prescribe the regulations substantially as submitted by EPA, or prescribe them in modified form, or publish in the Federal Register a notice that it is not prescribing any regulation in response to EPA's submission together with its reasons therefor.
  Section 611 (c)(2), as amended, also provides that if EPA believes that FAA’s action with respect to a regulation proposed by EPA “does not protect the public health and welfare from aircraft noise or sonic boom,” EPA shall consult with FAA and may request FAA to review and report to EPA on the advisability of prescribing the regulation originally proposed by EPA. That request shall be published in the Federal Register; FAA shall complete the review requested and report to EPA in the time specified together with a detailed statement of FAA’s findings and the reasons for its conclusion and shall identify any impact statement filed under § 102 (2) (C) of the National Environmental Policy Act of 1969, 83 Stat. 853, 42 U. S. C. § 4332 (2) (c), with respect to FAA’s action. FAA’s action, if adverse to EPA’s proposal, shall be published in the Federal Register.
  Congress did not leave FA A to act at large but provided in § 611 (d), as amended, particularized standards:
  “In prescribing and amending standards and regulations under this section, the FA A shall'—
  “(1) consider relevant available data relating to aircraft noise and sonic boom, including the results of research, development, testing, and evaluation activities conducted pursuant to this Act and the Department of Transportation Act;
  “(2) consult with such Federal, State, and interstate agencies as he deems appropriate;
  “(3) consider whether any proposed standard or regulation is consistent with the highest degree of safety in air commerce or air transportation in the public interest;
  “(4) consider whether any proposed standard or regulation is economically reasonable, technologically practicable, and appropriate for the particular type of aircraft, aircraft engine, appliance, or certificate to which it will apply; and
  “(5) consider the extent to which such standard or regulation will contribute to carrying out the purposes of this section.”
  The original complaint was filed on May 14, 1970; the District Court entered its judgment November 30, 1970; and the Court of Appeals announced its judgment and opinion March 22, 1972 — all before the Noise Control Act of 1972 was approved by the President on October 27, 1972. That Act reaffirms and reinforces the conclusion that FA A, now in conjunction with EPA, has full control over aircraft noise, pre-empting state and local control.
  There is, to be sure, no express provision of pre-emption in the 1972 Act. That, however, is not decisive. As we stated in Rice v. Santa Fe Elevator Corp., 331 U. S. 218, 230:
  “Congress legislated here in a field which the States have traditionally occupied. . . .' So we start with the assumption that the historic police powers of the States were not to be superseded by the Federal Act unless that was the clear and manifest purpose of Congress. . . . Such a purpose may be evidenced in several ways. The scheme of federal regulation may be so pervasive as to make reasonable the inference that Congress left no room for the States to supplement it. . . . Or the Act of Congress may touch a field in which the federal interest is so dominant that the federal system will be assumed to preclude enforcement of state laws on the same subject. . . . Likewise, the object sought to be obtained by the federal law and the character of obligations imposed by it may reveal the same purpose. ... Or the state policy may produce a result inconsistent with the objective of the federal statute.”
  It is the pervasive nature of the scheme of federal regulation of aircraft noise that leads us to conclude that there is pre-emption. As Mr. Justice Jackson stated, concurring in Northwest Airlines, Inc. v. Minnesota, 322 U. S. 292, 303:
  “Federal control is intensive and exclusive. Planes do not wander about in the sky like vagrant clouds. They move only by federal permission, subject to federal inspection, in the hands of federally certified personnel and under an intricate system of federal commands. The moment a ship taxis onto a runway it is caught up in an elaborate and detailed system of controls.”
  Both the Senate and House Committees included in their Reports clear statements that the bills would not change the existing pre-emption rule. The House Report stated: “No provision of the bill is intended to alter in any way the relationship between the authority of the Federal Government and that of the State and local governments that existed with respect to matters covered by section 611 of the Federal Aviation Act of 1958 prior to the enactment of the bill.” The Senate Report stated: “States and local governments are preempted from establishing or enforcing noise emission standards for aircraft unless such standards are identical to standards prescribed under this bill. This does not address responsibilities or powers of airport operators, and no provision of the bill is intended to alter in any way the relationship between the authority of the Federal government and that of State and local governments that existed with respect to matters covered by section 611 of the Federal Aviation Act of 1958 prior to the enactment of the bill.”
  These statements do not avail appellants. Prior to the 1972 Act, § 611 (a) provided that the Administrator “shall prescribe and amend such rules and regulations as he may find necessary to provide for the control and abatement of aircraft noise and sonic boom.” 82 Stat. 395. Under §611 (b)(3) the Administrator was required to “consider whether any proposed standard, rule, or regulation is consistent with the highest degree of safety in air commerce or air transportation in the public interest.” 82 Stat. 395. When the legislation which added this section to the Federal Aviation Act was considered at Senate hearings, Senator Monroney (the author of the 1958 Act) asked Secretary of Transportation Boyd whether the proposed legislation would “to any degree preempt State and local government regulation of aircraft noise and sonic boom.” The Secretary requested leave to submit a written opinion, and in a letter dated June 22, 1968, he stated:
  “The courts have held that the Federal Government presently preempts the field of noise regulation insofar as it involves controlling the flight of aircraft. ... H. R. 3400 would merely expand the Federal Government's role in a field already preempted. It would not change this preemption. State and local governments will remain unable to use their police powers to control aircraft noise by regulating the flight of aircraft.”
  According to the Senate Report, it was “not the intent of the committee in recommending this legislation to effect any change in the existing apportionment of powers between the Federal and State and local governments,” and the Report concurred in the views set forth by the Secretary in his letter.
  The Senate version of the 1972 Act as it passed the Senate contained an express pre-emption section. But the Senate version never was presented to the House. Instead, the Senate passed, with amendments, the House version; the House, also with amendments, then concurred in the Senate amendments. The Act as passed combined provisions of both the House and Senate bills on the subject that each had earlier approved. When the blended provisions of the present Act were before the House, Congressman Staggers, Chairman of the House Committee on Interstate and Foreign Commerce, in urging the House to accept the amended version, said:
  “I cannot say what industry’s intention may be, but I can say to the gentleman what my intention is in trying to get this bill passed. We have evidence that across America some cities and States are trying to pass noise regulations. Certainly we do not want that to happen. It would harass industry and progress in America. That is the reason why I want to get this bill passed during this session.”
  When the House approved the blended provisions of the bill, Senator Tunney moved that the Senate concur. He made clear that the regulations to be considered by EPA for recommendation to FAA would include:
  “proposed means of reducing noise in airport environments through the application of emission controls on aircraft, the regulation of flight patterns and aircraft and airport operations, and modifications in the number, frequency, or scheduling of flights [as well as] . . . the imposition of curfews on noisy airports, the imposition of flight path alterations in areas where noise was a problem, the imposition of noise emission standards on new and existing aircraft — with the expectation of a retrofit schedule to abate noise emissions from existing aircraft — the imposition of controls to increase the load factor on commercial flights, or other reductions in the joint use of airports, and such other procedures as may be determined useful and necessary to protect public health and welfare.” (Emphasis added.)
  The statements by Congressman Staggers and Senator Tunney are weighty ones. For Congressman Staggers was Chairman of the House Committee on Interstate and Foreign Commerce which submitted the Noise Control Act and Report; and Senator Tunney was a member of the Senate Committee on Public Works, which submitted the Act and Report.
  When the President signed the bill he stated that “many of the most significant sources of noise move in interstate commerce and can be effectively regulated only at the federal level.”
  Our prior cases on pre-emption are not precise guidelines in the present controversy, for each case turns on the peculiarities and special features of the federal regulatory scheme in question. Cf. Hines v. Davidowitz, 312 U. S. 52; Huron Portland Cement Co. v. Detroit, 362 U. S. 440. Control of noise is of course deep-seated in the police power of the States. Yet the pervasive control vested in EPA and in FAA under the 1972 Act seems to us to leave no room for local curfews or other local controls. What the ultimate remedy may be for aircraft noise which plagues many communities and tens of thousands of people is not known. The procedures under the 1972 Act are under way. In addition, the Administrator has imposed a variety of regulations relating to takeoff and landing procedures and runway preferences. The Federal Aviation Act requires a delicate balance between safety and efficiency, 49 U. S. C. § 1348 (a), and the protection of persons on the ground. 49 U. S. C. § 1348 (c). Any regulations adopted by the Administrator to control noise pollution must be consistent with the “highest degree of safety.” 49 U. S. C. § 1431 (d)(3). The interdependence of these factors requires a uniform and exclusive system of federal regulation if the congressional objectives underlying the Federal Aviation Act are to be fulfilled.
  If we were to uphold the Burbank ordinance and a significant number of municipalities followed suit, it is obvious that fractionalized control of the timing of takeoffs and landings would severely limit the flexibility of FAA in controlling air traffic flow. The difficulties of scheduling flights to avoid congestion and the concomitant decrease in safety would be compounded. In 1960 FAA rejected a proposed restriction on jet operations at the Los Angeles airport between 10 p. m. and 7 a. m. because such restrictions could “create critically serious problems to all air transportation patterns.” 25 Fed. Reg. 1764-1765. The complete FAA statement said:
  “The proposed restriction on the use of the airport by jet aircraft between the hours of 10 p. m. and 7 a. m. under certain surface wind conditions has also been reevaluated and this provision has been omitted from the rule. The practice of prohibiting the use of various airports during certain specific hours could create critically serious problems to all air transportation patterns. The network of airports throughout the United States and the constant availability of these airports are essential to the maintenance of a sound air transportation system. The continuing growth of public acceptance of aviation as a major force in passenger transportation and the increasingly significant role of commercial aviation in the nation’s economy are accomplishments which cannot be inhibited if the best interest of the public is to be served. It was concluded therefore that the extent of relief from the noise problem which this provision might have achieved would not have compensated the degree of restriction it would have imposed on domestic and foreign Air Commerce.”
  This decision, announced in 1960, remains peculiarly within the competence of FAA, supplemented now by the input of EPA. We are not at liberty to diffuse the powers given by Congress to FAA and EPA by letting the States or municipalities in on the planning. If that change is to be made, Congress alone must do it.
  Affirmed.
  Burbank Municipal Code § 20-32.1. The ordinance provides an exception for “emergency” flights approved by the City Police Department.
  The Court of Appeals held that the Burbank ordinance conflicted with the runway preference order, BUR 7100.5B, issued by the EAA Chief of the Airport Traffic Control Tower at the Hollywood-Burbank Airport. The order stated that “[procedures established for the Hollywood-Burbank airport are designed to reduce community exposure to noise to the lowest practicable minimum. . . The Court of Appeals concluded that the ordinance “interferes with the balance set by the FAA among the interests with which it is empowered to deal, and frustrates the full accomplishment of the goals of Congress.” 457 F. 2d 667, 676. In view of our disposition of this appeal under the doctrine of pre-emption, we need not reach this question.
  Section 307 provides in relevant part as follows:
  “(a) The Administrator is authorized and directed to develop plans for and formulate policy with respect to the use of the navigable airspace; and assign by rule, regulation, or order the use of the navigable airspace under such terms, conditions, and limitations as he may deem necessary in order to insure the safety of aircraft and the efficient utilization of such airspace. . . .
  “(c) The Administrator is further authorized and directed to prescribe air traffic rules and regulations governing the flight of aircraft, for the navigation, protection, and identification of aircraft, for the protection of persons and property on the ground, and for the efficient utilization of the navigable airspace, including rules as to safe altitudes of flight and rules for the prevention of collision between aircraft, between aircraft and land or water vehicles, and between aircraft and airborne objects.”
  Section 7 (a) provides:
  “The Administrator, after consultation with appropriate Federal, State, and local agencies and interested persons, shall conduct a study of the (1) adequacy of Federal Aviation Administration flight and operational noise controls; (2) adequacy of noise emission standards on new and existing aircraft, together with recommendations on the retrofitting and phaseout of existing aircraft; (3) implications of identifying and achieving levels of cumulative noise exposure around airports; and (4) additional measures available to airport operators and local governments to control aircraft noise. He shall report on such study to the Committee on Interstate and Foreign Commerce of the House of Representatives and the Committees on Commerce and Public Works of the Senate within nine months after the date of the enactment of this Act.”
  Section 611 of the Federal Aviation Act, 49 U. S. C. § 1431, was added in July 1968. Act of July 21, 1968, Pub. L. 90-411, 82 Stat. 395. Prior to amendment by the 1972 Act, it provided in part that the Administrator, “[i]n order to afford present and future relief and protection to the public from unnecessary aircraft noise and sonic boom, . . . shall prescribe and amend such rules and regulations as he may find necessary to provide for the control and abatement of aircraft noise and sonic boom.” 49 U. S. C. § 1431 (a).
  Section 611 (b) (1), as amended, reads:
  “In order to afford present and future relief and protection to the public health and welfare from aircraft noise and sonic boom, the FAA, after consultation with the Secretary of Transportation and with EPA, shall prescribe and amend standards for the measurement of aircraft noise and sonic boom and shall prescribe and amend such regulations as the FAA may find necessary to provide for the control and abatement of aircraft noise and sonic boom, including the application of such standards and regulations in the issuance, amendment, modification, suspension, or revocation of any certificate authorized by this title. No exemption with respect to any standard or regulation under this section may be granted under any provision of this Act unless the FAA shall have consulted with EPA before such exemption is granted, except that if the FAA determines that safety in air commerce or air transportation requires that such an exemption be granted before EPA can be consulted, the FAA shall consult with EPA as soon as practicable after the exemption is granted.”
  Subsection (b)(2) provides:
  “The FAA shall not issue an original type certificate under section 603 (a) of this Act for any aircraft for which substantial noise abatement can be achieved by prescribing standards and regulations in accordance with this section, unless he shall have prescribed standards and regulations in accordance with this section which apply to such aircraft and which protect the public from aircraft noise and sonic boom, consistent with the considerations listed in subsection (d).”
  Section 102 reads in part as follows:
  “The Congress authorizes and directs that, to the fullest extent possible: (1) the policies, regulations, and public laws of the United States shall be interpreted and administered in accordance with the policies set forth in this chapter, and (2) all agencies of the Federal Government shall— . . . (C) include in every recommendation or report on proposals for legislation and other major Federal actions significantly affecting the quality of the human environment, a detailed statement by the responsible official on— (i) the environmental impact of the proposed action, (ii) any adverse environmental effects which cannot be avoided should 'the proposal be implemented, (iii) alternatives to the proposed action, (iv) the relationship between local short-term uses of man’s environment and the maintenance and enhancement of long-term productivity, and (v) any irreversible and irretrievable commitments of resources which would be involved in the proposed action should it be implemented. Prior to making any detailed statement, the responsible Federal official shall consult with and obtain the comments of any Federal agency which has jurisdiction by law or special expertise with respect to any environmental impact involved. Copies of such statement and the comments and views of the appropriate Federal, State, and local agencies, which are authorized to develop and enforce environmental standards, shall be made available to the President, the Council on Environmental Quality and to the public as provided by section 552 of Title 5, and shall accompany the proposal through the existing agency review processes.”
  Section 611 (c) (3) of the Federal Aviation Act, as amended, provides that if FAA files no statement under § 102 (2) (C) of the National Environmental Policy Act “then EPA may request the FAA to file a supplemental report, which shall be published in the Federal Register within such a period as EPA may specify (but such time specified shall not be less than ninety days from the date the request was made), and which shall contain a comparison of (A) the environmental effects (including those which cannot be avoided) of the action actually taken by the FAA in response to EPA’s proposed regulations, and (B) EPA’s proposed regulations.”
  H. R. Rep. No. 92-842, p. 10.
  S. Rep. No. 92-1160, pp. 10-11.
  See n. 5, supra.
  Hearing before the Aviation Subcommittee of the Senate Committee on Commerce on S. 707 and H. R. 3400, Aircraft Noise Abatement Regulation, 90th Cong., 2d Sess., 29.
  S. Rep. No. 1353, 90th Cong., 2d Sess., 6.
  The letter from the Secretary of Transportation also expressed the view that “the proposed legislation will not affect the rights of a State or local public agency, as the proprietor of an airport, from issuing regulations or establishing requirements as to the permissible level of noise which can be created by aircraft using the airport. Airport owners acting as proprietors can presently deny the use of their airports to aircraft on the basis of noise considerations so long as such exclusion is nondiscriniinatory.” (Emphasis added.) This portion as well was quoted with approval in the Senate Report. Ibid.
  Appellants and the Solicitor General submit that this indicates that a municipality with jurisdiction over an airport has the power to impose a curfew on the airport, notwithstanding federal responsibility in the area. But, we are concerned here not with an ordinance imposed by the City of Burbank as “proprietor” of the airport, but with the exercise of police power. While the Hollywood-Burbank Airport may be the only major airport which is privately owned, many airports are owned by one municipality yet physically located in another. For example, the principal airport serving Cincinnati is located in Kentucky. Thus, authority that a municipality may have as a landlord is not necessarily congruent with its police power. We do not consider here what limits, if any, apply to a municipality as a proprietor.
  118 Cong. Rec. 35868.
  Id., at 35886.
  Id., at 37075.
  Id., at 37083.
  Id., at 37317.
  8 Weekly Comp. Pres. Docs. 1582, 1583 (Oct. 28, 1972).
  The Administrator has adopted regulations prescribing noise standards which must be met as a condition to type certification for all new subsonic turbojet-powered aircraft. 14 CFR pt. 36. On January 30, 1973, FAA gave advance notice of proposed rulemaking for the control of fleet noise levels (FNL) of airplanes operating in interstate commerce. 38 Fed. Reg. 2769. (The regulations would not pertain to carriers also operating in foreign commerce). The proposed rules are designed to limit FNL prior to July 1, 1978, when the covered aircraft become subject to the requirements of 14 CFR pt. 36.
  The FNL would be determined as a function of the takeoff and approach noise levels of each airplane in the fleet and the number of takeoffs and landings of the fleet. Until July 1, 1976, the cumulative noise level of any fleet subject to regulation could not exceed the FNL during the previous 90-day base period. In 1976 each fleet would be required to reduce its FNL by 50% of the difference between the original base-period level and the level ultimately required by 14 CFR pt. 36.
  In order to insure efficient and safe use of the navigable airspace, FAA uses centralized “flow control,” regulating the number of aircraft that will be accepted in a given area and restricting altitudes and routes that may be flown. Flow control has resulted in the Los Angeles Air Route Traffic Control Center holding aircraft on the ground at the Hollywood-Burbank Airport.
  Prior to April 1970, 21 regional Air Route Traffic Control Centers exercised independent control over traffic flow in their areas. In April 1970 FAA established a Central Flow Facility to coordinate flow control throughout the Air Traffic Control system. This change was necessitated because no regional center “had enough information to make a judgment based on the overall condition of the ATC system. . . .” Fourth Annual Report of the Secretary of Transportation for Fiscal Year 1970.
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