What Friday’s nationwide FAA ground stop shows about centralized systems and aging infrastructure

On Friday afternoon, November 13, 2026, the United States stopped every departing flight in the country, not because of the usual culprits, such as weather, nor was there any reported evidence of a cyberattack. Rather, according to US Transportation Secretary Sean Duffy’s preliminary account, the analog switches and routers that carry air-traffic-control communications “got overloaded with data” and began providing controllers with inconsistent information.

You may be asking yourself why this is relevant to ham radio or communications preparedness. Well, I’m sharing this because the same vulnerabilities exist in many of the centralized systems we depend on every day. For those of us interested in independent communications and preparedness, understanding how these systems fail is just as important as understanding how our own equipment works.

What actually happened

For just over four hours, aircraft already in the air were allowed to continue and land, and when the FAA lifted the order, thousands of flights had been cancelled.

That outcome showed us once again how highly centralized America’s air-traffic-control system is, with too much of it still running on decades-old equipment. When a shared part of that system fails, the consequences can be felt across the entire country, ultimately leading to the cautious decision to halt nationwide flight operations.

The United States has 22 Air Route Traffic Control Centers that handle the high-altitude, en-route portion of flights. When those centers lose reliable radio communications or radar, controllers cannot safely manage traffic through the nation’s airspace.

A ground stop normally holds departures at one airport for weather or a local equipment problem, but on Friday the FAA Command Center applied it nationally, with Advisory 111 stating that “due to extraordinary circumstances and for reasons of safety,” all airports were ground-stopped until further notice, inbound international flights would be handled case by case, and aircraft already inflight were not ordered down.

This was not a 9/11-style landing order, since after the September 11 attacks the FAA halted civilian traffic and directed airborne aircraft to land at the nearest available airports, whereas Friday’s order was a departure stop, as Homeland Security Secretary Markwayne Mullin emphasized when he said, “This isn’t another 9/11. I cannot repeat that enough.” It was the first nationwide ground stop since January 2023, and the second since 9/11, with some sources timing the official stop at four hours and 25 minutes.

A concise timeline

All times are Eastern Standard Time, with UTC in parentheses. Friday, November 13, 2026, unless noted.

• 3:10 p.m. (20:10 UTC). Ground stop for flights to Chicago O’Hare (equipment outage). Midway follows at 3:17 p.m. (20:17 UTC).
• 3:36 p.m. (20:36 UTC). Duffy later said radar and communications became unstable at this time at en-route centers and approach-control facilities.
• 3:53–3:54 p.m. (20:53–20:54 UTC). Official start of the nationwide ground stop. Flightradar24 counted 4,042 flights airborne and bound for U.S. airports.
• 4:16 p.m. (21:16 UTC). Duffy announces a communication issue “impacting all Air Route Traffic Control Centers.”
• 5:02 p.m. (22:02 UTC). The FAA calls it “a temporary telecommunications outage” and says all flights were halted. “Every flight has been accounted for.”
• About 5:20–5:31 p.m. (22:20–22:31 UTC). Mullin says there is “no indication as of yet” of anything “nefarious,” and that officials are “not ruling out anything at this point.”
• 5:45–5:46 p.m. (22:45–22:46 UTC). Advisory 120 keeps the national stop in place, changes the reason to “COMMUNICATIONS FAILURE,” and allows coordinated departures as en-route facilities recover.
• 8:15 p.m. (01:15 UTC, November 14). Duffy says the airspace reopens. The cancelling advisory, Advisory 005, is signed at 8:19 p.m. (01:19 UTC, November 14). The FAA says it “thoroughly tested” its systems before flights resumed.

What we know about the cause, and what we don’t

After the lift, Duffy told a White House briefing that the country has “an incredibly old air traffic control system” running on “TDM telecoms, so this is analog telecom,” explaining that the switches and routers “got overloaded with data” and “started to give us inconsistency in the data.” Apparently, this caused radar and communications instability from 3:36 p.m. (20:36 UTC), and while the FAA “didn’t lose all telecom” and “didn’t lose all radar,” the stop was issued “because of an abundance of caution,” leading him to observe that “It’s an old system that went down. It went down everywhere.”

This remains a Cabinet-level explanation rather than a published FAA finding, and Duffy did not say what triggered the overload, while Mullin noted that investigators had “seen zero evidence” of a cyberattack or an AI attack and that “it appears this was mechanically driven, however, we’re still looking,” with officials also denying any connection to Thursday’s Microsoft service disruption. Separately, and still unconfirmed, CBS News and later Reuters (citing airline officials) reported that an update to an L3Harris-operated private communications network caused a reboot and crash, though L3Harris has not confirmed the account, and neither has the FAA or DOT.

A Single Point of Failure?: L3Harris Technologies

L3Harris Technologies is a major U.S. defense and communications contractor, providing critical communications infrastructure for both civilian aviation and military operations.

In civilian aviation, L3Harris operates and modernizes the FAA Telecommunications Infrastructure (FTI), a private nationwide network connecting more than 4,400 FAA and some Department of Defense facilities. The network supports tens of thousands of communications services, including voice, radar, weather information, flight data, and video used by air traffic controllers and other aviation personnel.

Under its managed-service arrangement, L3Harris owns and maintains network equipment, leases the underlying telecommunications circuits, and is responsible for operating the network. Originally developed under a contract awarded to Harris Corporation in the early 2000s, the FTI network is being modernized, replacing aging copper lines and time-division multiplexing (TDM) equipment with fiber-optic connections, IP-based networking, satellite communications, and wireless technologies where appropriate.

L3Harris also supports other FAA systems, including Automatic Dependent Surveillance–Broadcast (ADS-B), Data Comm, and System Wide Information Management (SWIM).

Beyond civilian aviation, L3Harris supplies communications equipment and systems to the U.S. military, including handheld, portable, vehicle-mounted, and airborne radios, satellite communications terminals, tactical data links, and naval communications systems. Many of these technologies are designed to maintain reliable communications under demanding operational conditions, including environments where interference, equipment failures, or disrupted infrastructure can affect conventional networks.

The company’s involvement in both civilian and military communications makes it a significant provider of mission-critical infrastructure. Its operation of the FAA’s nationwide FTI network is particularly relevant to the November 13 ground stop, given reports that a network update may have contributed to the telecommunications failure. However, that connection remains unconfirmed by the FAA, DOT, and L3Harris.

This is a pattern, not a one-off

Friday was not the first time a failure in a shared, aging piece of the system stopped a great deal of American aviation at once.

On January 11, 2023, the FAA issued the previous nationwide departure stop after the Notice to Air Missions system failed. A later FAA review found that contract personnel from Spatial Front, Inc. had unintentionally deleted files while synchronizing the live primary database with its backup. The agency stated that it found no evidence of a cyberattack. The ground stop lasted about 90 minutes, affected more than 10,000 flights, and led to more than 1,000 cancellations, demonstrating how the failure of a single nationwide system can bring flight operations across the country to a halt.

In spring 2025, the Philadelphia facility that handles Newark-area approach control repeatedly lost radar and radio, including a roughly 90-second blackout on April 28 that was later attributed by the DOT inspector general to a burnt copper wire, and on May 9 primary and backup communications both failed for about 90 seconds, which served as a reminder that redundancy is not real when the backup is as fragile as the primary.

Friday was larger, and the official preliminary cause points at the same condition of decades-old analog gear, copper lines, and a network so centralized that instability at the centers produced a national halt, as Duffy put it when he said, “We have old switches, old routers, copper lines.”

The lesson for its own sake

We all understand the benefits of centralized systems, since they let a country run a single, consistent airspace, yet Friday showed the cost when the shared infrastructure fails, with the problem, in Duffy’s phrase, going down everywhere.

For those of us who build our own communications systems, the lesson is straightforward. Many of the large systems we depend on every day rely on centralized infrastructure and aging equipment. When that infrastructure fails, the consequences may not be limited to one location but can affect an entire country.

HF amateur radio is an excellent example of off-grid communications. Using NVIS or long-distance skywave propagation, radio operators can establish communications between individual stations or groups of stations across distances ranging from a few dozen to thousands of miles, without relying on telephone switches, internet routers, cell towers, or commercial telecommunications networks.

The lesson from Friday’s nationwide FAA ground stop is that even highly sophisticated communications systems can become vulnerable when too much of their operation depends on shared infrastructure. Having backup equipment is important, but those backups provide little protection if they rely on the same systems that have already failed. Real resilience requires independent alternatives, whether we’re talking about a nationwide air-traffic-control network or the communications systems we build for ourselves.

When shared switches, routers, and telecommunications networks fail, our own communications capabilities should not necessarily fail alongside them.

73,
Julian OH8STN

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