NEW YORK (AP) — American Airlines grounded all flights across the U.S. for most of Tuesday afternoon because of a computer outage. Flights resumed at 4:30 p.m. EDT. But the airline expects delays to linger throughout the evening. More than 720 flights were canceled, including 400 in Dallas and 200 in Chicago. More than 750 additional flights were delayed, according to flight tracking site FlightAware.

If you are stranded, here's what to do:

— To avoid a potentially long wait at the airport, think about canceling. American is offering free reservation changes and refunds for stranded passengers. If customers must travel and are not yet at the airport, they can rebook through American Airlines reservations or through another carrier and American will honor the fare difference, the airline announced. Flights are fuller than ever before, so it is unlikely there are many available seats on other carriers. If a customer chooses not to travel Tuesday, they can change a reservation without being charged a fee or receive a full refund.