United, Frontier Expand Routes as Spirit Airlines Shrinks Network

United Airlines and Frontier Group are aggressively expanding their flight networks to capture market share from Spirit Airlines, which recently filed for bankruptcy protection for the second time in less than a year. The moves come as Spirit discontinues service to 11 US cities and restructures operations amid growing financial pressure.

United Airlines announced on Sep. 4 it is launching new routes to 15 cities where Spirit operates. The airline is also deploying larger aircraft on the Chicago–LaGuardia corridor to enable better connectivity to these newly added destinations. “If Spirit suddenly goes out of business, it will be incredibly disruptive, so we are adding these flights to give their customers other options if they want or need them,” says Patrick Quayle, Senior Vice President of Global Network Planning and Alliances, United Airlines.

Spirit Airlines responded by asserting its intention to remain operational. “While we appreciate the obsession certain airline executives have with us, we are focused on competing and running a great operation,” says Duncan Dee, Senior Vice President Of Corporate Communications, Spirit Airlines. “Suggesting anything else is wishful thinking on the part of a high-cost airline looking to eliminate a low-cost competitor so they can fulfill their ultimate goal of charging American travelers the highest fares possible to visit the people and places they love.”

Florida-based Spirit Airlines has halted service to cities including Portland, Oregon, and San Diego, and canceled plans to begin service to Macon, Georgia, originally scheduled for October. According to financial disclosures, the airline’s operating expenses in the most recent quarter equaled 118% of its revenue, prompting further operational reductions.

Frontier Group, another ultra low-cost carrier, says it is launching 22 new routes, adding to the 20 routes it introduced in late August to cities previously dominated by Spirit. These new connections span domestic destinations as well as markets in Latin America and the Caribbean.

Frontier has the highest seat overlap with Spirit at 39%, compared to United’s 18%, according to Tom Fitzgerald, Analyst, TD Cowen. As Spirit reduces capacity and exits key markets, both low-cost and full-service carriers are moving to fill the gap, with Frontier and United leading the response through new route announcements.

Spirit Airlines filed for Chapter 11 bankruptcy in New York on Aug. 29, 2025, its second filing in under a year. The company reported assets and liabilities between US$1 billion and US$10 billion. It says that operations, tickets, and loyalty programs would continue unaffected. Shares fell 46% after the announcement.

The filing follows a failed restructuring in early 2025, which eliminated US$795 million in debt. Spirit plans to cut costs further, reduce fleet size, and scale back its network. A US$2.9 million retention deal was signed with CEO Dave Davis to support the new strategy.

The airline is also in renewed talks with Frontier Group about a possible merger. Spirit had previously agreed to a US$3.8 billion acquisition by JetBlue in 2022, but the deal was blocked in 2024 on antitrust grounds. The company is facing rising costs, grounded aircraft, and cash flow concerns.