The United States Federal Aviation Administration (FAA) has lifted a nationwide flight ground stop after a disruption to radar and communication systems affected air traffic control operations, causing more than 25,100 flight delays and over 6,600 cancellations.

The restriction, imposed on Friday, November 13, lasted for nearly five hours before being lifted at about 8:15 p.m. Eastern Time. More than 3,500 aircraft were already airborne when the disruption occurred, but safety procedures allowed them to continue to their destinations.

US Transportation Secretary Sean Duffy said the disruption began around 3:36 p.m. Eastern Time after air traffic control systems started generating inconsistent data.

He linked the failure to ageing network equipment, including switches and routers, as well as overloaded copper communication lines.

Medical evacuation and law enforcement flights were allowed to continue operating during the ground stop, while airlines faced widespread disruptions to domestic and international services.

Flight-tracking data cited by Yahoo News showed that by 9:30 p.m. Eastern Time, more than 25,100 flights had been delayed and over 6,600 cancelled within, into or out of the United States.

The FAA said operations would take time to return to normal as airlines worked to reposition aircraft, crews and passengers affected by the disruption.

US Homeland Security Secretary Markwayne Mullin said there was no evidence that the incident was caused by a deliberate attack or posed a national security threat.

The disruption has also drawn attention to concerns over ageing air traffic management infrastructure in Nigeria, where authorities are pursuing a major upgrade of the country’s surveillance and communication systems.

The Nigerian Airspace Management Agency (NAMA) has previously raised concerns about the age of its Total Radar Coverage of Nigeria (TRACON) system, which has been in operation since 2010. Some components are reportedly difficult to replace, while certain radar stations lack sufficient backup systems.

At the 55th Annual General Meeting of the Nigerian Air Traffic Controllers’ Association in Lagos on November 10, Aviation Minister Festus Keyamo announced that the Federal Government had approved a comprehensive overhaul of the country’s radar infrastructure.

Keyamo said new Very High Frequency radios and Voice Communication and Control Systems for 14 NAMA locations had passed factory acceptance tests in Norway.

He also disclosed that construction had commenced on a new NAMA headquarters and Air Traffic Management Centre in Abuja.

NAMA is also pursuing Automatic Dependent Surveillance-Broadcast technology, while plans have been reported to replace the existing TRACON network with radar systems from Spanish technology company Indra.

However, President of the Nigerian Air Traffic Controllers’ Association, Edino Ilemona Amos, said the planned upgrades had yet to result in significant improvements at operational workstations.

He warned that controllers could consider withdrawing their services if authorities failed to present a clear and comprehensive plan for addressing the infrastructure challenges.

The planned upgrades are expected to improve airspace surveillance, communication and safety while potentially increasing NAMA’s revenue from international overflights.

Industry estimates suggest that NAMA could generate as much as $1.5 billion annually if surveillance and communication coverage are significantly improved.

Aircraft passing through Nigerian airspace without landing are classified as overflights, for which NAMA charges between $75 and $195 depending on the flight category and route.

Overflight, en-route and terminal navigation charges account for about 75 per cent of NAMA’s revenue, while the statutory Ticket Sales Charge contributes the remaining 25 per cent.

NAMA currently generates roughly half of the estimated $1.5 billion potential, with ageing infrastructure and limited coverage identified as factors restricting its ability to monitor eligible flights and collect the associated charges.

The $1.5 billion projection remains an industry estimate rather than an official revenue target, with its achievement dependent on the successful deployment, maintenance and effective operation of modern surveillance and communication systems.