United Grounds All Mainline Flights Across US Over Tech Glitch, Says Expect 'Additional' Delays

On Wednesday, United Airlines Holdings Inc. (NASDAQ:UAL) temporarily grounded all mainline flights nationwide after a system glitch disrupted critical weight and balance calculations, reigniting scrutiny over the fragility of U.S. aviation infrastructure.

United Blames Technology Issue, Not Cyberattack

The airline confirmed that a "technology issue" with its weight and balance system—essential for flight safety—led to a halt on all mainline departures, reported ABC News.

"Due to a technology issue, we are holding United mainline flights at their departure airports," United said in a statement. "We expect additional flight delays this evening as we work through this issue. Safety is our top priority, and we'll work with our customers to get them to their destinations."

United said that the problem was not the result of a cyberattack, according to a statement shared with the publication. Flights already in the air continued to their destinations, and United Express flights were not affected.

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FAA Notices Confirm Ground Stops At Major Hubs

The Federal Aviation Administration (FAA) issued multiple ground stop notices at key United hubs, including Newark, San Francisco, Chicago, Denver and Houston, further amplifying the disruption across the airline's network, the report noted.

Aviation Infrastructure Under The Microscope

The incident adds to a string of aviation setbacks involving IT systems, cyberattacks and aging infrastructure.

• In July, Alaska Air Group Inc. (NYSE:ALK) grounded all mainline flights nationwide due to an IT systems outage.
• In January, JetBlue Airways Corp (NASDAQ:JBLU) was fined $2 million by the U.S. Department of Transportation for operating chronically delayed flights.
• Also in January, the U.S. Department of Transportation and the Department of Justice filed a joint lawsuit against Southwest Airlines Co. (NYSE:LUV), accusing the carrier of operating “chronically delayed flights” that disrupted passenger travel.
• The FAA in May considered reducing flight volumes at Newark due to outdated systems and staffing shortages.
• In 2024, a faulty CrowdStrike Holdings Inc. (NASDAQ:CRWD) software update for Microsoft Corporation's (NASDAQ:MSFT) Windows sparked a massive global IT outage, grounding major U.S. carriers including Delta Air Lines, Inc. (NYSE:DAL), United and American Airlines Group Inc. (NASDAQ:AAL). The disruption led to the cancellation of at least 2,500 flights and delays to over 8,000 across the U.S., with widespread ripple effects felt worldwide.
• In July, Russian carrier Aeroflot was hit by a major cyberattack that grounded over 100 flights, while a power outage at London Heathrow in March crippled operations and caused an estimated $100 million in airline losses.

Delta, Alaska Shine In Punctuality Rankings

Delta Air Lines and Alaska remain among the most punctual U.S. carriers, while United ranks tenth globally with an on-time rate of 80.93%, per aviation analytics firm Cirium.

In July, American Airlines delivered better-than-expected second-quarter 2025 results, demonstrating strong operational performance despite weather-related disruptions across its network.

Last month, United posted second-quarter revenue of $15.27 billion, falling short of the $15.35 billion consensus estimate. However, its adjusted earnings came in at $3.87 per share, topping analyst expectations of $3.77.

Price Action: United Airlines stock dipped 0.30% after hours, closing at $88.60, per Benzinga Pro. During the same period, shares of American Airlines dipped 0.17%, while JetBlue Airways Corp and Delta edged up 0.23% and 0.055%, respectively. Southwest Airlines shares were also up by 0.13%.

According to Benzinga's Edge Stock Rankings, UAL continues to show strong momentum across short, medium and long-term periods. Additional performance details are available here.

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Photo Courtesy: Wenjie Zheng on Shutterstock.com

Disclaimer: This content was partially produced with the help of AI tools and was reviewed and published by Benzinga editors.