United Airlines Grounds Flights Temporarily Due to Technology Glitch Causing Delays

United Airlines experienced a significant technology malfunction on the evening of August 6, 2025, leading to a temporary nationwide ground stop of its mainline flights from major US airports such as Chicago, Denver, Houston, San Francisco, and Newark. The airline identified the issue as a failure in its Unimatic system, which manages critical flight information including weight and balance calculations. Although the technology problem began around 6 p.m. Eastern Time and was resolved after several hours, over 1,000 flights were delayed and more than 40 canceled, as reported by flight tracking service FlightAware. Flights already airborne at the time of the stoppage continued to their destinations, and regional United Express flights were not directly affected, though delays there were possible due to congestion. Passengers reported long waits on tarmacs and delays exceeding two hours, with the airline committing to cover related customer expenses such as meals and accommodations by treating this as a preventable delay. US Transportation Secretary Sean Duffy confirmed the issue was specific to United and not linked to the broader national air traffic control system. The incident reflects vulnerabilities in airline IT systems and follows similar outages in the industry earlier this year. The airline is working to fully restore normal operations amid ongoing residual delays.