A commuter airline that serves Charleston and the Upstate under contracts with larger carriers filed for bankruptcy protection Thursday.

Republic Airways Holdings Inc. said the reorganization is not expected to disrupt its flight schedule.

“The process allows Republic and its subsidiaries to continue normal business operations while restructuring the company’s finances and contractual relationships,” according to a written statement.

Indianapolis-based Republic operates a fleet of short-haul planes that ferry passengers to hub airports for the nation’s three largest carriers — American Airlines, Delta Air Lines and United Continental.

At Charleston International Airport, the company flies only as an American affiliate, according to a route map on its website. It operates local flights to and from Miami, Washington, D.C., and Philadelphia.

CEO Bryan Bedford said Republic has tried for several months to restructure its debts and renegotiate contracts, but talks show “no apparent prospect of a near-term resolution.”

“It’s become clear that this process has reached an impasse and that any further delay would unnecessarily waste valuable resources of the enterprise,” Bedford said in the statement.

He also said Republic planes that have been grounded by “a lack of pilot resources” have cut into revenue in recent quarters.

Republic offers regional passenger service with more than 1,200 daily flights to more than 100 cities in 39 states, Canada and the Caribbean. Its only other South Carolina route flies Delta passengers between Greenville-Spartanburg International Airport and Detroit.

The bankruptcy filing in New York is the first for a large U.S. carrier since American sought protection from creditors in 2011.

Republic said it has sufficient financial resources to meet its working capital and operating expenses during the court-supervised restructuring process.

“We worked hard to avoid this step,” Bedford said of the filing.

Republic’s pilot shortage is tied partly to a now-resolved labor dispute. Also, flight crews at regional carriers are being hired away by larger airlines, which are reporting full planes and record profits.

Contact John McDermott at 843-937-5572.