American Airlines temporarily grounded flights due to technical glitch

American Airlines briefly grounded its U.S. flights Tuesday morning due to a technical problem, snarling travel during what carriers expect to be a period of record demand for the holidays.

By 7:55 a.m. ET, the ground stop had been lifted, an American Airlines spokeswoman told CNBC. The ground stop lasted for less than an hour but more than 900 American Airlines mainline flights had been delayed, according to flight-tracking site FlightAware. That was more than 38% of American’s schedule for Tuesday, and more delays than any other U.S. carrier. Only 11 mainline flights were canceled, however.

The airline’s subsidiary regional carrier Envoy also reported another 200 delayed flights. In addition to the earlier ground stop, American was also facing thunderstorms in the Dallas-Fort Worth area, where its biggest hub is located.

The problem was a network hardware issue involving a platform using DXC Technology, a vendor that maintains the flight operating system that lets flights leave the gate, American said in a statement.

The system is tied to critical data like an aircraft’s weight and balance, which is required before a flight can leave the gate.

“That issue has been resolved and flights have resumed,” the carrier said in a statement. “We sincerely apologize to our customers for the inconvenience this morning.”

The Federal Aviation Administration said American had requested the ground stop.

Airlines routinely request ground stops, which hold flights at origin, so that destination airports aren’t overwhelmed by flights with nowhere to park when there are disruptions. In addition to technical problems, ground stops are put in place for thunderstorms and other severe weather.

American was operating a smaller schedule on Christmas Eve compared with other days around the Christmas holiday. The carrier didn’t have any cancellations tied to the issue, a spokeswoman said.

Airlines’ patchwork systems of critical technology platforms have gained more attention lately after periods of mass flight cancellations such as Southwest‘s meltdown during the 2022 year-end holiday season and Delta‘s struggle to recover from the CrowdStrike outage this past summer.

Correction: The ground stop was issued Tuesday. An earlier version misstated the timing.