American Airlines grounded all its flights across the U.S. on Tuesday after an unidentified computer problem hit its reservation system.
"We are now in a system-wide ground delay until 4:00pm CT as we work to resolve this issue. We apologize for any inconvenience," the airline said in a message on Twitter.
The problem was causing "intermittent outages" to its reservation system, the airline said. More details were not immediately available.
American said it would offer travelers impacted by the problem refunds or itinerary changes at no charge, but was unable to modify Tuesday reservations until the problems were solved. In March the airline carried an average of 313,000 passengers worldwide on its network per day.
The airline first posted that its system was offline shortly after 11 a.m. Central Time (16:00 GMT).
The airline industry is hugely reliant on computers to manage the numerous passenger, baggage, scheduling and control systems that need to work in complete harmony to avoid chaos. For that reason, when a failure happens it typically affects tens of thousands of people and can have a knock-on effect for days.
