(a) Beginning with the fiscal year following the first calendar year in which an airport has more than .25 percent of the total number of boardings in the U.S., the sum of the amount that would be apportioned under 49 U.S.C. 47114 to the public agency controlling that airport in a fiscal year, after application of §158.95, and the projected PFC revenues to be collected in such fiscal year, shall not be less than the sum of the apportionment to such airport for the preceding fiscal year and the PFC revenues collected in the preceding fiscal year.

(b) Paragraph (a) of this section shall apply for fiscal years 2000 through 2003.