UPDATE: 4:45 p.m. ET -- American Airlines is flying airplanes again after hours of delays due to computer problems. "Our systems have been fully restored, however we expect continued flight delays and cancellations throughout the remainder of the day," the company posted on Facebook.
The company added, "It is important to note we see no evidence that today’s technical outage is related to the tragic events in Boston."
No information was given explaining the cause of the computer crash that downed the American Airlines fleet.
ORIGINAL POST: Citing a computer system failure, American Airlines has grounded all flights nationwide.
American asked the Federal Aviation Administration to halt its flights until 5 p.m. EDT, according to a tweet from the company account. An estimate from the flight tracking service FlightAware estimates that about 900 flights would be delayed if service resumed at 5 p.m. as planned.
The company is unable to access, alter or change reservations, including booking passengers on other airlines.
The FAA issued a ground stop, preventing any American flights from taking off, explaining in a statement, "American Airlines requested the ground stops because of problems with its reservation system." A spokesman tells TN, that other airlines have asked the FAA to issue partial ground stops due to problems accessing reservation systems.
The exact cause is unclear. Early reports blamed the airlines reservation system Sabre. An American Airlines tweet from 12:19 p.m. ET reads: "Our reservation & booking tool Sabre is offline. We're working to resolve as quickly as we can. We apologize for any inconvenience."
Some passengers are stuck on planes while others can't make reservations or change them.
American has taken to Twitter to personally respond to a flood of social media travel rage, responding individually to dozens of passengers, some complaining, some mocking; others praising the company's gate staff.
The Airline says it will offer refunds or update travel at no charge, once the reservation system is back up.
United Airlines experienced a similar glitch last year when integrating its reservation system with Continental. According to the AP, on one day in August, 580 flights were delayed and on another in November 636 flights were delayed.