The United States experienced a rare nationwide aviation shutdown on Friday after the Federal Aviation Administration (FAA) grounded departing flights across the country following a communication failure affecting air traffic control centres.

The disruption, which lasted more than four hours, was ordered over safety concerns after technical problems affected Air Route Traffic Control Centres responsible for coordinating aircraft movements across the country.

The FAA subsequently lifted the ground stop at about 8:15pm Eastern Time, allowing flight departures to resume after technicians tested the affected systems. However, aviation authorities and airlines warned that delays and cancellations could continue into Saturday as operations returned to normal.

US Transportation Secretary Sean Duffy confirmed the initial shutdown in a social media post, saying the FAA had issued a nationwide ground stop following a communication problem affecting all Air Route Traffic Control Centres.

He added that FAA technicians were investigating the disruption and would provide updates as more information became available.

In its advisory, the agency directed that aircraft departures remain suspended until further notice, while international flights would be handled on a case-by-case basis.

The communication failure affected regional facilities responsible for managing aircraft travelling between airports, raising concerns about the ability of controllers to maintain safe coordination without reliable communication systems.

Reports from the affected facilities indicated that some controllers experienced failures involving radio frequencies and automated systems used to communicate with pilots and coordinate aircraft movements.

The situation was described in aviation terminology as “ATC Zero”, meaning an air traffic control facility could not provide its normal control services.

Although some aircraft can operate in certain airspace under visual flight rules without conventional air traffic control services, the disruption significantly affected scheduled commercial operations, forcing airlines to delay departures, cancel services and divert aircraft.

At least 600 flights were diverted during the disruption, while thousands of others experienced delays or cancellations, according to flight-tracking and aviation reports.

The situation also created uncertainty for passengers at major airports, including Newark Liberty International Airport, where travellers faced cancellations and delays as they sought information about their journeys and alternative accommodation.

Two law enforcement officials initially told media outlets that preliminary information did not suggest a cyberattack was responsible for the incident. The Federal Bureau of Investigation also monitored developments as authorities investigated the disruption.

At a subsequent White House briefing, Homeland Security Secretary Markwayne Mullin said there was no evidence indicating that the outage was a deliberate attack against the United States.

Duffy later pointed to the country’s ageing air traffic control infrastructure, explaining that overloaded routers and switches within the legacy telecommunications system had produced inconsistent data, prompting the decision to halt operations as a precaution.

The FAA said it had tested the affected systems before allowing departures to resume.

The incident was particularly significant because it marked only the second nationwide ground stop of its kind since the September 11, 2001, attacks.

The previous shutdown occurred in January 2023, when a malfunction involving the FAA’s Notice to Air Missions (NOTAM) system disrupted the distribution of critical flight safety information and forced authorities to suspend domestic departures.

Friday’s incident once again drew attention to the condition of the country’s air traffic management infrastructure and the need to modernise systems responsible for coordinating thousands of daily flights.

Although the nationwide restriction has been lifted, the disruption left airlines working to reposition aircraft and crews, with passengers advised to confirm their flight schedules directly with their carriers before travelling to airports.