No-frills air travel pioneer Spirit Airlines filed for bankruptcy protection on Monday, after struggling with a long run of quarterly losses, a failed merger attempt and upcoming debt maturities.

Spirit Airlines says it will continue flying as it files for Chapter 11 bankruptcy protection. Monday's announcement follows years of losses and a failed merger attempt for the low-cost carrier.

Spirit Airlines, which advocates low-cost air ticket sales, recently declared Chapter 11 bankruptcy due to insurmountable losses.