United Airlines faced delays due to a technology issue that caused ground stops at major US airports. The airline reported a problem with its Unimatic system, which holds flight information, on Wednesday evening. As a result, over 1,000 flights were delayed, affecting about 35% of the airline’s scheduled flights.
The Federal Aviation Administration (FAA) issued ground stops for United flights at several US airports, including Chicago, Washington D.C., Denver, Houston, and San Francisco. The issue was resolved by around 10pm ET, but hundreds of travelers faced delays on Wednesday night.
United’s CEO Scott Kirby briefed Transportation Secretary Sean Duffy on the “internal tech outage” and FAA officials provided support to help clear up the flight backlog. The airline confirmed that the outage was not related to a cyberattack.
Regional express flights were unaffected during the network outage, and all flights already in the air continued to their destinations.
Source: https://www.axios.com/2025/08/07/united-ground-stop-us-tech-issue