United Airlines faced a major disruption on Wednesday evening, August 6, 2025, when a technology issue forced the carrier to ground all mainline flights nationwide, as reported by ABC News. The problem, linked to the airline’s weight and balance computer system, began shortly after 6 p.m. ET and led to over 1,000 flight delays and more than 40 cancellations, according to FlightAware. “Due to a technology issue, we are holding United mainline flights at their departure airports,” United stated, emphasizing, “Safety is our top priority, and we’ll work with our customers to get them to their destinations.” The airline clarified the outage was not a cyberattack, addressing social media speculation.
The Federal Aviation Administration issued ground stops at United’s major hubs, including Chicago, Denver, Houston, Newark, and San Francisco, at the airline’s request, per Reuters. The issue affected United’s Unimatic system, which feeds critical flight data, including weight and balance calculations essential for safe takeoffs, according to FlightGlobal. Flights already airborne continued to their destinations, and United Express regional flights were unaffected. “The underlying technology issue has been resolved, and, while we expect residual delays, our team is working to restore our normal operations,” United said in a late Wednesday statement, noting it would cover meals and hotels for impacted passengers.
Passengers faced significant inconvenience, with many stranded on tarmacs or at gates. At Chicago’s O’Hare Airport, thousands were packed into planes, with one traveler, Nancy Gonzalez, telling ABC News, “So we’re all sitting there like sardines in this little airplane… haven’t eaten, I’m hungry. Ten hours from Flint. I could have walked.” Another passenger, Johan Kotze, expressed frustration at New Orleans’ Louis Armstrong International Airport, where delays threatened his connecting flights to Mauritius, requiring him to rebook travel and accommodations, per AP News. Social media posts on X reflected widespread irritation, with some users speculating about a cyberattack despite United’s assurances.
Key impacts of the disruption include:
- Flight Delays: Over 1,000 flights delayed, with 40+ cancellations reported.
- Affected Hubs: Ground stops hit Chicago, Denver, Houston, Newark, and San Francisco.
- Passenger Support: United to cover meals and hotels for those impacted.
The outage, resolved after a few hours, adds to recent aviation IT challenges, following incidents like Alaska Airlines’ three-hour grounding in July, per The Guardian. United, which ranks 10th globally for on-time performance at 80.93%, according to Cirium, is now focused on minimizing further disruptions. Passengers are advised to check flight statuses and retain documentation for potential refunds under DOT rules, per VisaVerge. The incident underscores the fragility of airline technology systems as carriers work to restore traveler confidence.
Sources: ABC News, Reuters, FlightGlobal, AP News, The Guardian, VisaVerge, Cirium
