Frontier Airlines I.P.O. Signals a Travel Industry Recovery

“We just believe we’ve got more embedded growth, we’ve also got lower costs, and we believe we’ve got a great brand that positions us well in the low-fare space,” Mr. Biffle said.

The airline claims it is unique among low-cost airlines. While Spirit tends to serve more-crowded markets and Allegiant Air less-crowded ones, Frontier is more evenly distributed. The airline said it kept planes moving for more hours every day than most other major airlines and offers some flights only a few days a week, allowing it to serve smaller cities. In addition to Denver, Frontier has a big presence in Orlando, Fla., and Las Vegas.

Frontier also claims to be more fuel-efficient than its peers, which it hopes will appeal to environmentally conscious consumers.

The airline earned $251 million in 2019 before losing nearly as much last year. It has about $1 billion in cash or cash equivalents and employs about 5,000 people.

Deregulation of the U.S. airline industry in 1978 paved the way for the growth of low-cost carriers, which tend to operate direct, point-to-point flights, often to secondary airports in major cities — an approach pioneered by Southwest. That strategy makes it easier to put planes and crews to efficient use, allowing the airlines to offer relatively low fares. The more traditional hub-and-spoke model used by American, United and Delta is more expensive to maintain but easier to grow once established.

The ultra-low-cost model is a more recent creation, one that Europe’s Ryanair is often credited with popularizing. Companies that use it are much more aggressive about keeping costs low and maximizing revenue. These airlines tend to use their planes an hour or two more each day than other airlines and tend to cram more and smaller seats into planes. They also charge for lots of services that even many conventional discount airlines include in the ticket price, such as seat selection or printed boarding passes.

But larger airlines are unlikely to easily cede ground to Frontier and its ilk. In March, for example, United, which operates the most flights at the Denver airport, announced plans to add dozens of nonstop flights between small Midwestern cities and a handful of tourist destinations. Even before the pandemic, United and other large airlines were copying ultra-low-cost companies by offering lower fares and charging for more services.