American Airlines spokeswoman Stacey Frantz said Tuesday that the system was fixed by 4:30 p.m. EDT. But the airline expects to see flight delays and cancellations throughout the rest of the day.
Tracking service FlightAware says that as of mid-afternoon, American has canceled more than 700 flights and another 765 flights are delayed.
Passengers are describing long airport lines and frustration at a lack of information from airline employees.