You’re bumped from a flight
By law, your carrier has to make it up to you. The rules are very specific. Assuming the airline doesn’t get you to your destination within an hour of your original arrival time, you’re entitled to double the one-way fare, up to $675, according to Department of Transportation regulations. If you arrive more than two hours late, it’s four times the fare, up to $1,350. Ask the desk agent nicely and you might be able to secure meal vouchers as well, though the law doesn’t require that they be provided.
You volunteer your seat
Flight overbooked? If you do give up your seat, the airline will know your good deed prevented others from being involuntarily bumped, and your heroism should be rewarded generously. United Airlines offers volunteers up to $10,000 for giving up their seats—no joke—but your compensation will likely be much less. The amount depends on what you can negotiate and how badly the carrier needs your seat—and this is just one of the 13 secrets airlines aren’t telling you. Ask for cash (though the law doesn’t mandate that you get it); vouchers often come with blackout dates and other restrictions.