US air travel disruptions enter third day with over 5,200 flights affected

US air travel disruptions continued into their third day on Sunday, with over 5,200 flights already affected. According to aviation data site FlightAware, more than 1,600 flights nationwide were canceled and almost 3,600 were delayed on Sunday. This comes after Saturday's cancellations of over 6,400 US flights and delays of more than 8,000.

Transportation Secretary Sean Duffy stated on ABC's "This Week" program that there is no evidence of a cyberattack or malicious intent in the matter, but the cause of the disruptions remains unclear. Duffy predicted that flights would return to normal by Sunday, but "probably fully normal" by Monday. He emphasized the Federal Aviation Administration's focus on keeping passengers safe.

The disruptions were caused by a systemwide ground stop issued by the FAA on Friday, which halted nearly all departing flights for almost five hours. This was the longest nationwide halt to US air travel since the September 11, 2001, al Qaeda attacks. According to officials, the installation of a new router at a remote facility led to a situation in which other air traffic control centers were overloaded with a flood of data.

The router replacement at an FAA facility in El Dorado, Arkansas, triggered problems with a recently replaced router in Amarillo, Texas, which started broadcasting and overloading routers at other air traffic control centers across the country. The FAA disabled the "functionality of the originating routers" and did the same for about 60 similar routers in the air traffic control system.

Despite this, the FAA still does not know what ultimately caused the problem that occurred with maintenance work that had been done thousands of times before without issue. Duffy said the worker who installed the router was "a good American patriot, we believe, a veteran — so we don't think that someone tried to sabotage the network on the install," but the root cause remains unknown.

The disruptions highlight the strain on a US air traffic control system beset by aging technology, equipment and communications problems, and a shortage of several thousand controllers. The routers that experienced issues were purchased in 2001 and were obsolete by 2006, Duffy said. Since Friday, Duffy has called for $50 billion in funding to upgrade air traffic control systems.

President Donald Trump weighed in on the issue on Sunday, calling for additional funding from US lawmakers. Duffy's plea for more money drew skepticism from US Representatives Rick Larsen and André Carson, who noted that of the $12.5 billion approved in 2025 for upgrades to the air traffic control system, about $11 billion remains unspent.

Key points

• Over 5,200 flights have been affected by US air travel disruptions.
• The disruptions were caused by a systemwide ground stop issued by the FAA on Friday.
• Transportation Secretary Sean Duffy predicts a return to normalcy by Monday.