Spirit Airlines officially filed for bankruptcy protection Monday after the pioneer of no-frills travel in the U.S. struggled with a long run of quarterly losses, failed merger attempts and looming debt maturities.

Budget carrier Spirit Airlines announced early Monday that it has filed for Chapter 11 bankruptcy, saying it expects to spend the next year going through the process.

Spirit Airlines Inc. filed for a voluntary, pre-arranged Chapter 11 bankruptcy early Monday, capping a tumultuous period for the low-cost airline in which efforts to merge with two rivals fell through.