If an airline does not voluntarily file for bankruptcy, it may lose its air operator's certificate (AOC) over the state of its finances. The certificate grants permission to sell and operate flights in the US and requires the holder to demonstrate that it has the necessary planes, staff, safety systems, and financial resources to run a functional airline. Most recently, charter airline Tailwind Air lost its AOC in January 2025 after struggling to bring in traffic on its routes between Northeastern cities like New York and Boston. In December 2025, Swedish aviation regulatory agency Transportstyrelsen revoked H-Bird's AOC due to the airline's poor financial situation. The airline has not run any flights since January 2026.