Technology failures disrupted digital services at Delta Air Lines and United Airlines on Oct. 6, raising questions about the resilience of the technology infrastructure supporting major U.S. carriers and whether the incidents could be related.
There is currently no evidence that the disruptions resulted from a cyberattack.
Delta described its incident as a “limited global technology issue” that affected data connectivity to some of the airline’s behind-the-scenes systems. Customers reported difficulty using Delta’s website and mobile application, while some travelers reported delays during the disruption.
Delta said its systems were stabilizing Tuesday afternoon and that employees were working to keep flight operations moving safely as systems returned to normal.
United experienced a separate technology problem affecting its website and mobile application. The airline said the incident was connected to an outside vendor and prevented some customers from logging into their MileagePlus accounts. United said the problem was resolved and maintained that its flight operations were not affected.
The most visible operational effects appeared to involve Delta, particularly at its Atlanta hub and at several other airports where passengers reported difficulty boarding or accessing airline systems. United, by contrast, said its vendor-related technology problem affected customer access to its website, app and MileagePlus accounts but did not disrupt flight operations.
The identity of the vendor has not been publicly disclosed.
Adding to questions about whether the incidents might share a common cause, outage-monitoring services also recorded reports of problems involving American Airlines’ website and application. American had not confirmed a related technology failure as of Tuesday afternoon.
It remains unclear whether the problems at the airlines were connected or merely occurred within a similar timeframe.
The incidents nevertheless highlight an increasingly important aviation-security concern: airlines depend on complex networks of internal systems, cloud and communications infrastructure, and third-party technology providers. A failure at a widely used supplier can potentially affect multiple carriers simultaneously without involving a cyberattack.
The disruption recalls the July 2024 CrowdStrike incident, when a faulty cybersecurity software update caused widespread computer failures and severely disrupted airlines worldwide. That incident was also initially accompanied by speculation about a cyberattack but ultimately proved to be a software failure.
Atlanta had an FAA equipment outage and 34-minute ground stop on October 5 — the day before the Delta outage and some of the delays experienced in Atlanta may have been attributable to that issue.
Neither Delta nor United has reported that the Oct. 6 incidents involved malicious activity, unauthorized system access or compromised passenger information. The underlying cause of Delta’s connectivity problem—and whether it has any connection to United’s vendor-related outage—has not yet been publicly identified.