US flights restart after nationwide air traffic shutdown

US aviation authorities lifted a nationwide ground stop on Friday evening, allowing aircraft departures to resume after a communications failure halted flights for more than four hours and disrupted travel across the country.
The Federal Aviation Administration reopened the airspace at approximately 8.15pm Eastern Time after testing its systems, but warned that the resumption of departures would be gradual. Airlines faced thousands of cancellations and delays, with aircraft and crews scattered far from their scheduled positions.
Transportation Secretary Sean Duffy said ageing switches and routers had become overloaded with data, producing unreliable information for air traffic controllers. The disruption affected radar feeds and communications at control centres and terminal radar approach facilities, prompting the FAA to suspend departures as a safety precaution.
Duffy said the instability began at approximately 3.36pm, before the nationwide ground stop was imposed at 3.54pm. More than 3,500 aircraft were airborne when the problem emerged. Controllers continued guiding flights towards safe landings under established emergency procedures.
The secretary stressed that the entire radar and telecommunications network had not failed simultaneously. Instead, inconsistent information made it unsafe to continue normal operations until engineers could stabilise the system and verify that essential services were functioning reliably.
The FAA said its technicians had thoroughly tested the affected systems before authorising departures. The agency initially described the problem as communications issues affecting multiple air route traffic control centres, and its investigation into the precise sequence of failures continued.
Homeland Security Secretary Markwayne Mullin said officials had found no indication of a cyberattack. He described the failure as apparently mechanical, while acknowledging that investigators were still examining its cause. Authorities did not identify any deliberate interference with aviation systems.
Passengers encountered crowded terminals, lengthy queues and uncertainty over connecting flights as airlines suspended departures and struggled to revise schedules. The consequences extended beyond the four-hour stoppage because aircraft, flight crews and airport resources could not immediately return to their planned rotations.
Duffy cautioned that lifting the order did not mean every grounded aircraft could depart straight away. Airlines would have to account for available crews and operational restrictions, potentially leaving some services cancelled until Saturday as carriers worked through the backlog.
The disruption affected major airlines and airports nationwide, including domestic connections and international journeys. Flight diversions further complicated recovery, while travellers were advised to confirm their flight status directly with carriers before heading to airports.
The interruption also placed pressure on airline customer service teams handling rebookings and accommodation requests. Carriers were expected to prioritise the safe movement of aircraft and staff before restoring full timetables, with the pace of recovery varying by airport and available operating capacity.
At a White House briefing, Duffy linked the breakdown to the continued use of analogue telecommunications equipment, including older switches and copper-based connections. He said newer internet-protocol equipment already installed in parts of the network had remained operational during the incident.
The administration renewed its appeal for Congress to finance a comprehensive replacement of the air traffic control infrastructure. Duffy said $12.5 billion had been provided towards the programme, but additional funding was necessary to complete the planned overhaul.
The secretary argued that piecemeal repairs would not address the underlying vulnerabilities. His comments highlighted the difficulty of modernising essential aviation technology while maintaining uninterrupted service across one of the world’s busiest air transport networks.
Officials also examined whether work on network upgrades contributed to the overload. Duffy indicated that the investigation would establish whether the fault arose from equipment or its installation, rather than presenting a final technical explanation before engineers completed their assessment.
The shutdown was an unusually extensive intervention by the FAA, which normally manages localised ground stops during severe weather, congestion or equipment problems. A nationwide halt is reserved for circumstances in which the agency considers ordinary flight operations unsafe.
Although departing aircraft were held on the ground, flights already airborne were not ordered to land immediately at the nearest airport. Controllers instead coordinated arrivals while reducing the number of aircraft remaining in the national airspace system.
Duffy said fewer than 400 aircraft remained airborne when he last checked during the response, reflecting the progressive landing of planes that had already departed before the suspension took effect.