An American Airlines passenger Luciara Miranda waits to be helped at the ticket counter at Miami International Airport on April 16, 2013 in Miami, Fla. Thousands of American Airlines travelers became stranded today when the airline was forced to ground all its flights after a nationwide problem with its computer systems. - 

It's not clear what caused American's problems with its computer system.

“American’s not telling anyone exactly one happened,” said Brett Snyder, who runs the blog He says all we know is that American Airlines was unable to access its reservation system, known as Sabre*, along with other systems. “And so American was unable to do a lot of things that are required of daily business."

Among them: call up its passenger list, print boarding passes, track bags and even help calculate the weight of the plane. When an airline loses touch with its computers,  it’s as if it were brain dead. American Airlines CEO Tom Horton went on YouTube yesterday to apologize and explained that it did have “redundancies” -- computer speak for back-ups -- but those failed too.

But that has some airline watchers saying the aging computer system itself is the problem, said Joe Brancatelli, the publisher of, a website for business travelers.

“The Sabre system that American Airlines uses dates back to the 1950s**,” Brancatelli said.

Back then, fewer people flew and most tasks were done by hand. Brancatelli says to grow, the airlines started to computerize. But since then, the number of fliers has exploded, airlines have merged and the business has become incredibly complex.

“Rather than stop and start again, they’re always upgrading, updating changing stuff that was built in the 1950s,” Brancatelli said.

And computer systems really start to show their age when airlines merge. A little more than a year ago, United and Continental teamed up, they merged their computer systems, there was chaos for months. Brancetelli says given what happened yesterday, if the American and US Air merger goes through, we could be in for a replay.

*Correction: An earlier version of this story incorrectly misspelled the name of American Airline's reservation system. It is Sabre. **The system was developed in 1960.