; and (2) in clause (ii) by striking and (g) and inserting (g), and (i) . (c) Preservation of existing within perimeter service Nothing in this section, or the amendments made by this section, shall be construed as authorizing the conversion of a within-perimeter exemption or slot at Ronald Reagan Washington National Airport that is in effect on the date of enactment of this Act to serve an airport located beyond the perimeter described in section 49109 of title 49, United States Code. 503. Refunds (a) In general Chapter 423 of title 49, United States Code, is amended by inserting after section 42304 the following: 42305. Refunds for cancelled or significantly delayed or changed flights (a) In general In the case of a passenger that holds a nonrefundable ticket on a scheduled flight to, from, or within the United States, an air carrier or a foreign air carrier shall, upon request as set forth in subsection (f), provide a full refund, including any taxes and ancillary fees, for the fare such carrier collected for any cancelled flight or significantly delayed or changed flight where the passenger chooses not to— (1) fly on the significantly delayed or changed flight or accept rebooking on an alternative flight; or (2) accept any voucher, credit, or other form of compensation offered by the air carrier or foreign air carrier pursuant to subsection (c). (b) Timing of refund Any refund required under subsection (a) shall be issued by the air carrier or foreign air carrier— (1) in the case of a ticket purchased with a credit card, not later than 7 business days after the earliest date the refund was requested as set forth in subsection (f)