Policies differ on how long you might be sitting

— -- Regional airlines flying under major carriers' names are responsible for their own operations because they have their own operating certificates, issued by the Federal Aviation Administration. However, regional carriers typically are obligated to meet the same customer service standards. All major U.S. airlines have policies, usually posted on their websites, that state what they do for passengers aboard delayed planes. They generally follow guidelines established by their trade group, the Air Transport Association, which say airlines "will make every reasonable effort to provide food, water, restroom facilities and access to medical treatment."

The caveat: safety. Additional water, food and toilet servicing won't be delivered, the plane won't be allowed to return to the terminal, and passengers won't be allowed to get off if weather or limitations at the airport make it dangerous.

JetBlue has a schedule of compensation and gives vouchers for future travel to passengers delayed for reasons under its control. Most other carriers offer travel vouchers as compensation for delays that are under their control, but have no formal schedule of compensation. Airlines typically don't compensate passengers delayed on the ground because of weather or air-traffic congestion. Here's a summary of policies of the USA's largest carriers.