United Airlines planes at Denver International Airport in Denver, Colorado on Wednesday, July 2, 2025.
Aaron Ontiveroz | Denver Post | Getty Images
United Airlines said a technology issue that led to a brief grounding of its flights at U.S. airports on Wednesday had been resolved.
“While we expect residual delays, our team is working to restore our normal operations,” the airline said.
The outage, which lasted for more than an hour, prompted ground stops at several major United hub airports including Newark, Denver, Houston, and Chicago, according to the U.S. Federal Aviation Administration’s website.
United did not provide details of the technology issue that grounded flights, but a source familiar with the matter said the airline had suffered an outage of its weight calculation system.
As of 9:25 p.m. ET (0125 GMT on Thursday), flight tracking data from FlightAware showed that 870, or 28%, of United flights had been delayed on Wednesday.
United’s outage came a few weeks after Alaska Airlines grounded all of its flights for about three hours due to an IT outage for the second time in just over a year.
In April 2024, Alaska grounded its entire fleet due to an issue with the system that calculates the weight and balance of its planes.
