United Airlines flights grounded nationwide due to tech outage, delays expected despite fix

United Airlines says it has resolved a major technology outage that briefly grounded flights nationwide Wednesday, but the fallout is far from over.

In a statement released around 7:00 p.m. PT, the airline confirmed the issue had been fixed:

"We are working with customers to get them to their destinations after a technology disruption on Wednesday evening. The underlying technology issue has been resolved, and, while we expect residual delays, our team is working to restore our normal operations."

Earlier in the day, the Federal Aviation Administration (FAA) issued a ground stop that paused United flights at their departure airports across the country. FAA alerts specifically noted disruptions at major hubs in Chicago, Denver, Newark, Houston, and San Francisco.

What United passengers need to know about the delays

What we know:

United’s mainline flights were halted nationwide for part of Wednesday due to a system-wide tech failure.

The issue led to a cascade of delays across key airports and stranded travelers at gates and on planes.

While flights have resumed, the airline says "residual delays" should be expected into the evening.

These delays come during peak summer travel season, making the timing especially disruptive for passengers.

What we don't know:

United has not said what exactly caused the "technology issue" or whether it was internal or linked to third-party systems.

It’s also unclear how many total flights were delayed or canceled as a result of the disruption.

The airline has not disclosed if the issue impacted any data systems, safety operations, or customer information.

What they're saying:

In its public statement, United said:

"Safety is our top priority, and we’ll work with our customers to get them to their destinations."

The airline responded to frustrated customers on X (formerly Twitter), writing:

"Hey there, we apologize for the travel disruption today. Our teams are working to resolve the outage as quickly as possible. Thank you for your patience."

An Associated Press journalist onboard a United flight in New Orleans reported that passengers were told of a "systemwide" problem and asked to return to the terminal after boarding.

Traveler Johan Kotze, who was flying from New Orleans to Mauritius, said the delay would likely derail his multi-leg journey.

"It’s not very nice," Kotze told the AP.

United provides update on cause of outage

Late Wednesday night, United confirmed that the outage was caused by a disruption to Unimatic, a legacy system that houses key flight information. The system feeds data into other operations, including flight tracking and weight and balance calculations.

The issue began at 5:12 p.m. CDT and was resolved within a few hours, though delays continued into the evening.

United said it is treating the situation as a controllable delay, meaning it has offered compensation such as hotel stays when applicable.

The airline emphasized that the incident was not related to cybersecurity concerns that have recently affected other parts of the airline industry.

What's next:

United says it is working to get flights back on schedule, but recovery will take time. Passengers are advised to check their flight status online and prepare for possible rebookings or gate changes.

No additional alerts have been issued by the FAA as of Wednesday night.

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