To sue an airline for compensation, you typically start by filing a claim in Small Claims Court, which is designed for individuals to handle legal disputes without expensive lawyers. Before taking this step, you must have first attempted to resolve the issue directly with the airline’s customer service and received a formal denial. In the U.S., you would file in the jurisdiction where the airline does business or where the flight originated. You'll need to cite a specific breach of their "Contract of Carriage" or a violation of Department of Transportation (DOT) regulations, such as those regarding lost luggage or involuntary bumping. For international flights involving the EU or UK, you can often leverage Regulation (EC) No 261/2004, which provides standardized compensation for delays and cancellations. While the process involves a small filing fee and a court appearance, it is a powerful tool for passengers when airlines refuse to follow their own policies or federal consumer protection laws.