United Airlines temporarily grounded all mainline flights across the United States on Thursday due to an emergency fire alarm at its Network Operations Center in Arlington Heights, near Chicago. The precautionary measure, prompted by the alarm, led to the evacuation of the facility and a brief nationwide ground stop, disrupting approximately 200 flights, according to FlightAware.

Employees were swiftly relocated to a nearby backup facility to maintain operations. In a statement to FOX News, United Airlines explained, "A fire alarm sounded at our operations center, prompting employees to move to our nearby backup facility, resulting in a brief nationwide ground stop of United aircraft. Employees have since returned to the primary operations center, and the ground stop has been lifted. " The Federal Aviation Administration (FAA) issued an advisory around 6:30 PM local time, confirming the temporary suspension of United's operations. 

 While no fire was confirmed at the facility, the airline prioritized safety by halting flights and evacuating staff. The disruption, though significant, was short-lived, with normal operations resuming within an hour. The swift response and use of the backup facility minimized delays, allowing United to restore its flight schedule efficiently. 

 This incident underscores the airline's commitment to safety protocols, ensuring that precautionary measures are promptly enacted to protect passengers and staff. The event, while temporarily inconvenient for travelers, demonstrated United's ability to manage operational challenges effectively, leveraging backup systems to maintain service continuity.