American Airlines flights grounded by mysterious computer glitch

It was smooth flying for American Airlines passengers across most of the U.S. Thursday morning - unless you happened to be traveling through Chicago, Miami or Dallas, where computer problems caused delays and cancellations.

American Airlines technicians are trying to sort out why flights into and out of O'Hare International Airport were grounded for about 90 minutes along with those at Dallas-Fort Worth International Airport and Miami International Airport.

The computer meltdown affected check-ins for passengers from 11 a.m. to 12:30 p.m.

"We're definitely investigating it," American Airlines spokesman Leslie Scott said. "Our IT team is taking a look to diagnose what the problem was."

As of Thursday afternoon, the carrier was back to normal, albeit with some residual issues, including delays of 30 minutes or so on certain flights.

"We apologize for the inconvenience and are working to get our customers on their way as soon as possible," Scott said.

A total of six flights were canceled and 28 flights were delayed.

United Airlines passengers ran into a website outage Sept. 8 that affected checks-in, but not arrivals or departures.