A fire alarm at the United Airlines headquarters in Chicago’s Willis Tower caused a nationwide ground stop for all United flights on Thursday.
Evacuation and Temporary Relocation
In response to the alarm, United Airlines issued a statement confirming that employees at the Network Operations Center were evacuated and temporarily relocated to a nearby facility. The ground stop was lifted once staff returned to the primary operations center, returning to normal operations.
FAA Advisory and Passenger Reactions
The Federal Aviation Administration (FAA) issued an advisory regarding the ground stop, which affected airports across the country. Announcements were made at airports and inside United aircraft, leading to widespread social media posts from passengers. One user shared a video on X showing the announcement made inside a United plane.
United Airlines announcement to stop flight operations pic.twitter.com/N6QHqVPwNe
— Erick Q (@ErickFernandoQ) July 25, 2025
Impact on Flights
In its statement, United Airlines clarified that no flights were diverted, and United Express regional flight services were unaffected. As one of the largest airline operators in the U.S., United Airlines operates up to 4,600 daily flights on peak travel days as of summer 2025.
