Delta and United have issued nationwide travel waivers for eligible passengers booked to fly Friday or Saturday affected by Friday’s FAA ground stop. The FAA lifted the nationwide restriction Friday evening. United’s published terms offer qualifying replacement flights through Nov. 20. Delta’s window runs through Nov. 21. Check the date your original ticket was issued and the price shown on the replacement itinerary before you confirm a change.

Delta: Change and fly by Nov. 21

Delta’s air traffic control outage waiver covers travel on Nov. 13 and 14 systemwide for tickets issued on or before Nov. 13. Delta says to make the change and take the replacement flight by Nov. 21. It says it will waive the fare difference when qualifying travelers rebook in the same cabin, though its terms flag some cases where the original booking class is sold out. Changing your origin or destination can also raise the price.

Start with My Trips in the Delta app or on its website. Delta’s waiver page also offers eligible travelers the option to cancel and take an eCredit. If Delta canceled your flight and you decide against traveling, check your cash refund options before accepting a credit.

United: Keep the same cities and cabin

United’s travel alert gives the original travel dates as Nov. 13 and 14 and the ticket purchase cutoff as Nov. 12. Its waiver says eligible customers can move to a United flight through Nov. 20 and avoid the change fee and fare difference when they keep the same cities and cabin. United’s page also says affected passengers who cancel or skip the trip can get a refund. The carrier said it was canceling a significant number of Friday evening flights and contacting affected customers.

United flights headed to Chicago O’Hare

A separate FAA order held some United and United-affiliated flights headed to Chicago O’Hare at their departure airports. The order lists a scheduled cutoff of 8:45 p.m. Central Friday for flights from designated air traffic regions. Check your flight with United before leaving for the airport and check any onward flight separately if you’re connecting at O’Hare.

When to look for a refund

If you still need to travel, compare the replacement flight’s final arrival time and connections before changing anything. When a trip includes a separate ticket on a different airline, check that booking separately before assuming you can still make the connection.

If the airline cancels your flight or makes a qualifying schedule change and you decline alternate travel, federal refund rules generally entitle you to the eligible unused ticket value. The Transportation Department’s refund guidance explains when that payment is due. Keep the original itinerary and the carrier’s cancellation or change notice if you request a refund.