Book ahead and save at least $2 on select routes, with any travel funds from cancellation valid until 2022. Buy Now at DealBase Tips On the DealBase landing page, click "Southwest Airlines" in the top line to see this sale. We found this price on flights departing on August 31 from Nashville, TN (BNA) to Charleston, SC (CHS). Book this travel deal by June 12 for flights from May 26 through August 31. If you decide not to travel, as long as you cancel your flight at least 10 minutes before its scheduled departure, the funds used to pay for a nonrefundable ticket can be used through September 7, 2022.