Washington, November 2026 : US authorities are investigating the cause of a nationwide flight disruption after ageing air traffic control equipment became overloaded, triggering a temporary grounding of flights across the country. The Department of Homeland Security (DHS) said it had found no evidence of a cyberattack but was not ruling out the possibility as the investigation continued.
US Transportation Secretary Sean Duffy said communications and radar data at several air traffic control facilities became unstable on Friday afternoon (local time), disrupting aviation operations. He attributed the initial problem to overloaded legacy equipment but said officials were still examining the precise cause.
The Federal Aviation Administration (FAA) lifted the nationwide ground stop on Friday evening, allowing flights to resume. However, airlines were left dealing with delays and cancellations, with thousands of passengers facing disruptions to their travel plans.
Duffy cautioned that restoring normal flight schedules would take time, depending partly on the availability of pilots and cabin crew.
Addressing a White House briefing alongside Duffy, Homeland Security Secretary Markwayne Mullin said investigators had found no evidence of a cyberattack or unauthorised access to the air traffic control system. However, he stressed that the investigation was ongoing and officials were keeping all possibilities open.
Mullin also clarified that the disruption was not linked to a separate Microsoft outage.
More than 3,500 aircraft affected by system instability
According to Duffy, the disruption began at approximately 3:36 p.m. Eastern time, when air traffic control centres and terminal radar facilities started receiving inconsistent radar and communication data. More than 3,500 aircraft were airborne at the time.
He said the radar and communication systems had not completely failed. Pilots and air traffic controllers continued operating under established safety procedures to ensure aircraft landed safely. Essential medical and law enforcement flights were also permitted to continue.
Ageing air traffic control infrastructure under scrutiny
Both officials highlighted the age of America's air traffic control infrastructure, although the briefing did not establish exactly how the system became overloaded.
Mullin suggested that newer equipment and technology might have placed excessive demands on the older network. Duffy later rejected a suggestion that software patching by the FAA had triggered the disruption.
He explained that the older analogue system had been overwhelmed by data, while upgraded digital equipment had not experienced the same problem.
Duffy said officials were examining the technical details and he did not want to provide inaccurate information before the investigation was complete.
The affected facilities have since been brought back online after authorities took steps to reduce the load on the network. However, the transportation secretary warned that airlines would need time to clear the backlog of delayed and cancelled flights.
FAA faces questions over infrastructure modernisation
The incident has renewed concerns about the reliability of the US air traffic control network, which comprises airport control towers, terminal radar facilities and en route centres.
Air traffic controllers depend on communication and surveillance systems to monitor aircraft movements and safely guide planes through increasingly crowded US airspace.
The investigation is expected to examine the technical failure, the capacity of legacy equipment and the interaction between older analogue systems and newer digital technologies. Authorities have yet to announce a definitive explanation for the nationwide disruption.
