It's a mysterious rule...that helps passengers get to their destination a lot faster when a flight is cancelled. With more than three thousand flights cancelled last week, it probably would have come in handy for many travellers.
It's rule 240, it states that if an airline cancels a flight for any reason other than weather, they are responsible for putting you on the next flight to your destination, even if it's on another airlines.
Paula Dunlap was one of those passengers whose American Airlines flight was cancelled last week.
"I do not know what my rights are as far as getting money back or travelling or a different fare or what money they'll refund to me and that kind of thing."
Dunlap also says she was simply trying to get home. So she went to another ticket counter and paid for another flight home.
"I am not sure we are going to get the money back for the American flight or not."
But the process could have been easier if she used rule 240. American would have paid for her flight home, and saved her the out of pocket expense.
"You can ask the airlines for that and they'll do that for you." said Amarillo Travel Owner, Samarah Meil.
Meil also says passengers can also get travellers insurance.
"If you have to be delayed, they'll take care of you. If you have to stay at a hotel overnight and the airlines not going to pay for that. Or if they're having to have meals out of their pocket because they are not at their destination, or if they miss their cruise then that insurance will kick in and fly them to the port where that cruise will be."
Dunlap says airlines should consider adopting a new policy for cancelled flights.
"Call us, email us, but let us know before we get to the airport."