What Caused the FAA Ground Stop? Old Routers and Switches Overloaded

The nationwide Federal Aviation Administration (FAA) ground stop on November 13, 2026, was caused by overloaded equipment in the agency's ageing air traffic control communications network, according to US Transportation Secretary Sean Duffy.

The failure affected radar information and communications between air traffic controllers and aircraft, forcing the FAA to temporarily halt departing flights across the United States.

Duffy said the problem involved old switches and routers operating on the agency's legacy Time-Division Multiplexing (TDM) telecommunications system.

What caused the FAA ground stop?

According to Duffy, the FAA's older telecommunications equipment became overloaded with data, resulting in inconsistent information from the routers.

The instability began at approximately 3:36 p.m. Eastern Time on November 13, affecting radar and communications at air traffic control centres and Terminal Radar Approach Control (TRACON) facilities across the country.

Because controllers could not consistently rely on the information being transmitted through the affected systems, the FAA ordered a nationwide ground stop as a precaution.

In a briefing, Duffy explained that the agency was still relying on outdated telecommunications infrastructure, including older switches, routers and copper lines.

He said newer Internet Protocol (IP) switches installed as part of the modernisation effort remained operational, while the older equipment experienced problems.

What is TDM technology, and why did it fail?

Time-Division Multiplexing, commonly known as TDM, is a telecommunications technology that allows multiple signals to share a communication channel by assigning each signal a specific time slot.

The FAA still uses this older technology across parts of its telecommunications infrastructure to transmit information needed by air traffic control facilities.

Unlike modern internet-based networks, which transmit data using flexible packets, traditional TDM systems rely on fixed communication channels.

The technology itself was not described by officials as having suddenly stopped working everywhere. Instead, Duffy said the ageing switches and routers became overloaded and began producing inconsistent data.

That instability affected the reliability of information used by controllers to monitor aircraft and communicate with pilots.

Was the FAA ground stop caused by a cyberattack?

US officials said there was no evidence that the November 13 disruption was caused by a cyberattack.

Homeland Security Secretary Markwayne Mullin said there was no indication of a malicious attack when officials addressed the incident.

However, the precise technical trigger behind the equipment overload was not fully established in the initial public explanations.

The confirmed explanation from Duffy was that the FAA's older telecommunications hardware became overloaded with data, leading to inconsistent information across its air traffic control network.

How long did the FAA ground stop last?

The FAA issued the nationwide ground stop on Friday, November 13, after communications and radar instability was detected.

The restriction was lifted at approximately 8:15 p.m. Eastern Time, after more than four hours.

Duffy said more than 3,500 aircraft were in the air when the ground stop was issued. They were guided safely to land using established procedures.

Although departures resumed after the order was lifted, the disruption continued to affect airline operations as carriers worked through delays, cancellations and displaced aircraft.

Will the FAA replace its outdated equipment?

The incident has renewed attention on the FAA's long-running air traffic control modernisation programme.

Duffy said the government had already begun replacing older equipment with modern IP-based systems, but acknowledged that the transition was incomplete.

He said some newer switches remained operational during the incident, while the older hardware failed.

The administration has called on Congress to provide additional funding to complete the modernisation programme rather than continue relying on a patchwork of old and new infrastructure.

Reuters has also reported that the FAA's ageing technology has been a longstanding concern, with government assessments identifying numerous air traffic control systems that are unsustainable or potentially unsustainable.

The November 13 incident demonstrated how weaknesses in legacy telecommunications equipment can disrupt flight operations across the country.

What happens next?

The FAA's immediate priority is restoring normal operations and continuing its work to modernise the communications and radar infrastructure supporting US air traffic control.

Although the nationwide ground stop was lifted, airlines faced continuing disruption as they worked to reposition aircraft and crews.

The incident also raises a wider question about how quickly the FAA can replace its ageing infrastructure before another equipment failure affects the national aviation network.

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