Frontier Airlines is pushing deeper into Spirit Airlines’ core markets, unveiling 20 new routes as it seeks to become the “No. 1 low-fare carrier in the top 20 U.S. metro areas.”
The additions include eight new routes from Houston George Bush Intercontinental Airport, plus six apiece from Detroit Metropolitan Wayne County Airport and Fort Lauderdale-Hollywood International Airport.
“We see a clear path to being the No. 1 low-fare carrier in the top 20 U.S. metros,” Frontier CEO Barry Biffle says. “As industry capacity adjusts, we want to ensure consumers in those markets continue to have affordable flight options.”
Frontier’s network plans come as Spirit grapples with severe financial pressure. Having emerged from Chapter 11 in March, the South Florida-based carrier has warned of “substantial doubt” over its ability to continue operating over the next 12 months unless it secures new liquidity.
In recent filings, Spirit outlined potential asset sales, gate divestitures and additional cost cuts, while also furloughing pilots and trimming its schedule. Vice president of network planning, John Kirby, will also retire at the end of August.
Analysis of OAG Schedules Analyser data shows Spirit currently serves 18 of the 20 new Frontier routes, including high-frequency city pairs such as Baltimore–Fort Lauderdale, Fort Lauderdale–Houston and Detroit–Miami. The two exceptions are Houston–Philadelphia, which Spirit paused earlier this month, and Houston–San Salvador, which the ULCC intends to resume in December.
At Houston, where Frontier plans to launch eight new routes, Spirit is the second-largest carrier with a 5.8% seat share in August 2025, compared with Frontier’s 2.8%. At Detroit, Spirit has a 12.8% share compared with Delta’s dominant 70%, while Frontier holds just 2.2% as it works to expand. In Fort Lauderdale, Spirit’s largest base, the carrier holds nearly one-third of capacity across 65 routes, while Frontier’s footprint is limited to five routes today but will rise to 11 with its latest growth.
Frontier and Spirit already compete head-to-head on 108 routes, representing about 32% of Spirit’s network. The new expansion will deepen that overlap, adding fresh pressure on some of Spirit’s busiest leisure markets at a time when its finances are already under strain. The carrier posted a $246 million net loss in the second quarter as operating revenues fell 20.4% year over year to $1.02 billion, driven by a 23.9% cut in capacity and a 3.8-point drop in load factor.
