Check your airline's 'Contract of Carriage'
Every airline posts a contract of carriage on its website. Each is different; Northwest, for example, states that it will put you on another airline’s flight if you experience a missed connection and a Northwest flight is unavailable, while Delta, as mentioned, has the final say. Familiarizing yourself with—or even printing out—your airline’s current rules before you fly may save you angst later. And flying with companies that voluntarily abide by some rules is a good idea. JetBlue has since developed its own customer bill of rights, promising that you will never be stuck on a plane for longer than five hours and that you’ll be compensated with vouchers for future travel if you experience delays of more than one hour.