DALLAS — Airlines are cutting money-losing flights during the current travel slump, and that can cause headaches for passengers who bought tickets on those trips.

The airlines will usually rebook a passenger on another flight close to the original schedule. But sometimes the change can mean a delay of several hours — even overnight.

Travel experts say big disruptions are most common when travelers buy tickets months in advance for a vacation or holiday visit.

What can you do if the delay in your new flight ruins your plans?

"That's a tough one," says Glen MacDonell, director of lodging airline programs for the AAA travel club. "The airline will try to re-accommodate you or offer you a refund. In a lot of cases, neither of those are good options."

Most U.S. airlines say they will offer a full refund if they put you on a new flight that arrives more than 90 minutes earlier or later than you had planned.

But if air fares have risen since you bought your ticket, the refund won't cover the cost of buying another ticket on a different airline.

"It's going to happen more often with smaller airports where they're cutting back service," says George Hobica, the founder of airfarewatchdog.com.

Early next month, AirTran Airways is pulling out of Charleston, S.C., where it was credited with driving down fares by offering lower prices on service to Atlanta.

But if you hold a ticket on AirTran after Dec. 3, "You'll have to buy a more expensive ticket because those fares are going to skyrocket" when the discount carrier leaves, Hobica says.

Airlines also bump passengers when they switch a flight to a smaller plane. Some travelers believe airlines changed their trip to resell the original seat to a higher bidder.

Lew Davis, a middle school administrator in New York, says Delta tried to bump him from a $138 nonstop round trip to Denver at Christmas 2007 to a multistop itinerary on Delta's regional affiliates. After many phone calls and e-mails — he accused the airline of bait-and-switch sales tactics — Delta put him back on the nonstop, he says.

Delta spokeswoman Susan Elliott calls Davis' case an anomaly. She says the airline typically offers displaced customers a better flight, such as a nonstop instead of a one-stop, or a credit for future travel. Or they can get a full refund if the new arrival time is more than 90 minutes later than the original one.

Here's what other airlines say:

Continental will work with a customer to find a satisfactory new flight, or the customer can request a refund, says spokeswoman Mary Clark.