BOSTON — Spirit Airlines plans to suspend operations as early as Saturday morning unless there is an intervention, with a $500 million federal bailout stalled. Trump administration officials have been informed that the carrier may cease operations within the next 24 hours.

Cirium analytics shows more than 900 Spirit flights are scheduled for this weekend alone, representing more than 190,000 seats. The airline traces its roots to Metro Detroit, where it launched as a charter service in 1983.

A shutdown would reduce market capacity and likely lead to higher airfares on competing carriers. An analysis of Cirium data found that average fares jumped 23%, or roughly $60, for a round-trip flight when Spirit exited a route, while overall passenger volume fell 20% after the airline left a market.

"Any time you have a reduction in capacity and demand increases, airfares have nowhere to go but up. And that doesn't count the fares that are already rising because of the spike in fuel prices," said Peter Greenberg, a travel editor. Higher jet fuel costs resulting from the Iran war have contributed to increased ticket prices.

Customers holding tickets for future Spirit flights are entitled to full refunds if the airline goes out of business, though travelers may encounter obstacles obtaining them. "If you're holding a Spirit ticket for a flight that hasn't happened yet, you'll get that back from your credit card company under federal credit laws," Greenberg said.

Under the Fair Credit Billing Act, travelers should not cancel their tickets because they will need proof of non-delivery of service. "Watch what happens very closely, and if the airline ceases operation, call the credit card you used to buy the ticket and dispute the charge. The result is a non-delivery of service, which is grounds for disputing a charge," said Eric Rosen, director of travel content at The Points Guy. Airline loyalty points used for Spirit flights cannot be transferred to other carriers' loyalty programs.

United Airlines said it is preparing to support Spirit customers and employees and will provide more details soon. Airlines have not yet shared whether they will offer rescue fares for Spirit customers, and some travelers may have to turn to higher-priced carriers for a flight home.

"These rescue fares may be less expensive than the normal fares these airlines would charge, but would probably be more expensive than the Spirit fares," said Henry Harteveldt, founder of Atmosphere Research Group. He urged customers to keep copies of their Spirit itineraries in case another airline requires them.

"I do expect a lot of budget airlines will try to backfill Spirit somehow," Harteveldt said. "Airlines' plans have already been committed for the summer. But over time, within three to six months, I would not be surprised to see Frontier, Avelo, Breeze and Allegiant all take steps to enter markets that Spirit served," he said.