Miami Florida
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Travelers have one day only to purchase $20 flights with Frontier Airlines. The flash sale, which launched today and concludes tonight (or when seats sell out) is to celebrate the airline’s massive new airline order.

Indigo Partners, the private equity firm that owns Frontier and other low-cost carriers around the world, announced one of the biggest aircraft orders in history on Wednesday. Indigo inked a deal to purchase 430 new Airbus planes, and about 134 of those are planned to go to Frontier.

While the new fleet of Airbus A320neo and A321neo airplanes won't start being delivered until 2021, the budget airline isn’t waiting to commemorate the occasion.

Travelers have until 11:59 p.m. ET on November 15 to book the $20 tickets, which are available on nonstop, domestic flights from December 5 and December 16, and from January 9 until February 14.

There's a catch: To take advantage of the sale, travelers must be Discount Den members. If you don't already have one, a year's membership will set you back $49.99.

Highlights from the sale include $20 flights from New York City to Miami; from Atlanta to San Francisco or Los Angeles; and from Washington, D.C. to Denver, Orlando, and Austin. Flights are available from a number of major cities, and are not limited to short, regional flights.