United Airlines halts U.S. flights because of a system outage

United Airlines grounded flights across the country Wednesday because of a system outage and warned that it expected problems through the evening.

“Due to a technology issue, we are holding United mainline flights at their departure airports,” the airline said in a statement around 8:30 p.m. Eastern time. “We expect additional flight delays this evening as we work through this issue.”

Full stops for United’s flights were in place at airports, including its hubs in Chicago; Denver; Houston; Newark, New Jersey; and San Francisco, according to the Federal Aviation Administration’s website. An agency spokesperson directed questions to United.

On social media sites, customers posted reports of being stranded on tarmacs and being told to deplane after boarding. United’s account on social platform X replied to various complaints with comments citing a “system error” and a “tech outage.”

One traveler wrote on social media, “2 hours and counting,” with a video shot out a plane window showing the passenger’s jet and another grounded United airplane.

Tracking site FlightAware reported Wednesday evening that 27% of United’s flights for the day had been delayed.