On August 6, 2025, a system failure in United Airlines’ Unimatic platform disrupted air travel across the United States, leading to major delays and cancellations. The system, which provides important data such as aircraft weight, balance, and flight schedules, stopped working for several hours in the evening. According to aviation tracker FlightAware, the incident caused more than 1,000 flight delays and over 200 cancellations. Records showed that 35% of United flights were delayed and 7% were canceled that day. Chicago O’Hare International Airport reported 42 cancellations, most involving United flights. The disruption also affected domestic hubs in Denver, Newark, Houston, and San Francisco, as well as international flights to cities such as London, Frankfurt, and Munich. The cause of the problem has not been reported, but the system was restored later that night.

By August 7, 2025, United Airlines said that operations were slowly improving, although 11% of its flights were still delayed and 5% were canceled. The airline issued a travel advisory warning that flights to and from more than a dozen U.S. and international airports could still be affected. The Federal Aviation Administration said it was working closely with United to address the backlog. United stated that the failure was not linked to cybersecurity issues and promised to cover some passenger costs, such as hotel stays. Experts said the event showed the need for stronger backup systems in the airline industry.