A summer or fall getaway just got cheaper. Frontier Airlines' “1 Million Seats" fare sale is underway with deals starting at $19. The promotion ends on Monday April 29 and offers deals to many popular destinations in Frontier’s network including Atlanta, Austin, New York, Orlando, and more. While the fare sale may provide deep discounts, there are several restrictions on when passengers can actually use the tickets. The sale applies to flights on Tuesdays, Wednesdays, and Saturdays from May 10 through June 30 and then again from August 15 through October 31. International destinations, Florida destinations, and Las Vegas have additional booking restrictions.