A system outage at United Airlines disrupted travel for thousands of passengers on August 7, 2025, when a critical technology failure forced the airline to temporarily ground all its mainline flights across the United States. The problem started at 6:12 p.m. ET when United’s decades-old internal system called Unimatic experienced technical difficulties. This legacy system houses essential flight information that feeds data to other critical systems, including those that calculate aircraft weight and balance and track flight times. “Due to a technology issue, we are holding United mainline flights at their departure airports,” United said as the situation unfolded. The … Continue reading United’s Aging Unimatic System Failure Delays thousands Flights Nationwide