((a)) ** .—** Except as provided in this section, an amount apportioned under section 47114(c)(1) or (d)(2) of this title is available for making grants for any purpose for which amounts are made available under .

((b))

((1)) ** .—** An amount apportioned under is available to be obligated for grants under the apportionment only during the fiscal year for which the amount was apportioned and the 2 fiscal years immediately after that year or the 3 fiscal years immediately following that year in the case of a nonhub airport or any airport that is not a commercial service airport. Except as provided in paragraph (2), if the amount is not obligated under the apportionment within that time, it shall be added to the discretionary fund.

((2))

((A)) ** .—** Except as provided in subparagraph (B), if an amount apportioned under section 47114(d) is not obligated within the time specified in paragraph (1), that amount shall be added to the discretionary fund under , provided that—

((i)) amounts made available under paragraph (2)(A) shall be used for grants for projects in accordance with section 47115(d)(2) at airports eligible to receive an apportionment under section 47114(d)(2); and

((ii)) amounts made available under paragraph (2)(A) that are not obligated by July 1 of the fiscal year in which the funds will expire shall be made available for all projects in accordance with section 47115(d)(2).

((B)) ** .—** If an amount apportioned to an airport under section 47114(d)(2)(A) is not obligated within the time specified in paragraph (1), and the airport is located in a State participating in the State block grant program under section 47128, the amount shall be made available to that State under the same conditions as if the State had been apportioned the amount under section 47114(d)(2)(B).

((c)) ** .—**

((1)) An amount apportioned to a sponsor of a primary airport under is available for grants for any public-use airport of the sponsor included in the national plan of integrated airport systems.

((2)) ** .—** A sponsor of an airport may make an agreement with the Secretary of Transportation waiving the sponsor’s claim to any part of the amount apportioned for the airport under sections 47114(c) and 47114(d)(2)(A) if the Secretary agrees to make the waived amount available for a grant for another public-use airport in the same State or geographical area as the airport, as determined by the Secretary.

((d)) ** .—** An amount apportioned to a State under—

((1)) section 47114(d)(2)(B)(i) is available for grants for airports located in the State; and

((2)) section 47114(d)(2)(B)(ii) or (iii) is available for grants for airports described in section 47114(d)(2)(B)(ii) or (iii) and located in the State.

((e)) ** .—**

((1)) The Secretary shall use amounts available to the discretionary fund under for each fiscal year as follows:

((A)) At least 35 percent, but not more than $200,000,000, for grants for airport noise compatibility planning under section 47505(a)(2), for carrying out noise compatibility programs under section 47504(c), for noise mitigation projects approved in an environmental record of decision for an airport development project under this title, for airport development described in subparagraphs (O), (P), (Q), and (W) of section 47102(3), for airport development described in section 47102(3)(F), 47102(3)(K), or 47102(3)(L), and for water quality mitigation projects to comply with the Act of ( et seq.), approved in an environmental record of decision for an airport development project under this title. The Secretary may count the amount of grants made for such planning and programs with funds apportioned under section 47114 in that fiscal year in determining whether or not the requirements of the preceding sentence are being met in that fiscal year. The Secretary shall provide not less than two-thirds of amounts under this subparagraph and paragraph (3) for grants to sponsors of small hub, medium hub, and large hub airports.

((B)) At least 4 percent to sponsors of current or former military airports designated by the Secretary under for grants for developing current and former military airports to improve the capacity of the national air transportation system and to sponsors of noncommercial service airports for grants for operational and maintenance expenses at any such airport if the amount of such grants to the sponsor of the airport does not exceed $30,000 in that fiscal year, if the Secretary determines that the airport is adversely affected by the closure or realignment of a military base, and if the sponsor of the airport certifies that the airport would otherwise close if the airport does not receive the grant.

((2)) If the Secretary decides that an amount required to be used for grants under paragraph (1) of this subsection cannot be used for a fiscal year because there are insufficient qualified grant applications, the amount the Secretary determines cannot be used is available during the fiscal year for grants for other airports or for other purposes for which amounts are authorized for grants under .

((3)) ** .—** Beginning in fiscal year 2026, if the amount made available under paragraph (1)(A) was not equal to or greater than $150,000,000 in the preceding fiscal year, the Secretary shall issue grants for projects eligible under paragraph (1)(A) from apportionment funds made available under section 47114 that are not required during the fiscal year pursuant to subsection (b)(1) in an amount that is not less than—

((A)) $150,000,000; minus

((B)) the amount made available under paragraph (1)(A) in the preceding fiscal year.

((f))

((1)) ** .—** Subject to paragraph (2), if the Secretary finds that all or part of an amount of an apportionment under section 47114 is not required during a fiscal year to fund a grant for which the apportionment may be used, the Secretary may use during such fiscal year the amount not so required to make grants for any purpose for which grants may be made under section 48103. The finding may be based on the notifications that the Secretary receives under section 47105(f) or on other information received from airport sponsors.

((2))

((A)) ** .—** If the fiscal year for which a finding is made under paragraph (1) with respect to an apportionment is not the last fiscal year of availability of the apportionment under subsection (b), the Secretary shall restore to the apportionment an amount equal to the amount of the apportionment used under paragraph (1) for a discretionary grant whenever a sufficient amount is made available under section 48103.

((B)) ** .—** If restoration under this paragraph is made in the fiscal year for which the finding is made or the succeeding fiscal year, the amount restored shall be subject to the original period of availability of the apportionment under subsection (b). If the restoration is made thereafter, the amount restored shall remain available in accordance with subsection (b) for the original period of availability of the apportionment plus the number of fiscal years during which a sufficient amount was not available for the restoration.

((3))

((A)) ** .—** Of an amount newly available under , an amount equal to the amounts restored under paragraph (2) shall not be available for discretionary grant obligations under section 47115.

((B)) ** .—** Subparagraph (A) does not impair the Secretary’s authority under paragraph (1), after a restoration under paragraph (2), to apply all or part of a restored amount that is not required to fund a grant under an apportionment to fund discretionary grants.

((4)) ** .—** Nothing in this subsection shall be construed to authorize the Secretary to incur grant obligations under section 47104 for a fiscal year in an amount greater than the amount made available under section 48103 for such obligations for such fiscal year.

((g)) ** .—** The authority of the Secretary to make grants during a fiscal year from amounts that were apportioned for a prior fiscal year and remain available for approved airport development project grants under subsection (b) of this section may be impaired only by a law enacted after , that expressly limits that authority.