United Airlines was forced to issue a nationwide ground stop for its entire fleet after a fire alarm sounded at its operations center in Chicago.
The ground stop was confirmed in a Federal Aviation Administration (FAA) advisory note on July 24, 2025, with the instruction coming into effect at 23:26.
United Airlines described the ground stop as “brief”, with no requirement for any flights to be diverted. Its regional subsidiary airline United Express was unaffected.
A spokesperson for United Airlines said: “A fire alarm sounded at our operations center, which caused employees to move to our nearby backup facility and resulted in a brief nationwide ground stop of United aircraft. Employees have returned to our primary operations center, and the ground stop has been lifted.”
All @united flights grounded in Newark because of a fire alarm issue in Chicago control center? Is this for entire US? pic.twitter.com/FZWv8lUllf
— Brian Land (@brianland) July 25, 2025
The United Airlines ground stop comes just days after Alaska Airlines experienced a brief nationwide IT outage that grounded all of its flights.
The outage, on July 20, 2025, caused a temporary, system-wide ground stop for both Alaska Airlines and Air Horizon flights.
Following the incident, Alaska Airlines said: “We sincerely apologize for the inconvenience and encourage guests to check your flight status before heading to the airport.”
Both incidents come at a time when the efficiency of the US commercial aviation industry is high on the priority agenda for the Trump administration.