One L3Harris Router, 20,000 Flights: What Investigators Found Behind the FAA Shutdown

TLDR

• A router installed by L3Harris may have triggered a nearly five-hour US flight shutdown on Friday.
• Delta, United and American each canceled about 20% of Saturday flights, and JetBlue about 40%.
• The faulty router sent over 1,000 connection attempts every four to five seconds.
• Officials say it was not a cyberattack, and the FAA is still seeking the root cause.
• Transportation Secretary Sean Duffy wants $50 billion more for air traffic control upgrades.

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A single piece of network equipment may explain why US air travel stopped for nearly five hours on Friday. Government officials said a router installed by contractor L3Harris could be at fault. More than 20,000 flights have been disrupted since the shutdown began.

A SOFTWARE UPDATE CRASHED THE AIR TRAFFIC CONTROL COMMUNICATIONS NETWORK RUN BY $LHX L3HARRIS, CAUSING THE NATIONWIDE GROUND STOP

— Wall St Engine (@wallstengine) November 14, 2026

What Went Wrong Inside the FAA Network

Transportation Secretary Sean Duffy said L3Harris was doing routine maintenance at the time. The crew was switching phone and data lines from old copper wire to fiber at a remote site. Officials said routers in both Arkansas and Texas may have had problems.

Duffy said the new routers flooded other routers with more than 1,000 connection attempts every four to five seconds. That overload caused communication problems with planes and radar. It hit 17 of the FAA’s 22 en route centers.

The FAA then issued a nationwide ground stop because it could not find a root cause. FAA Administrator Bryan Bedford said the agency lost the ability for those routers to communicate data. He said the stop was a precaution in case a center lost all communications.

No facility went completely dark, the FAA said. Instead, data at the centers became unstable. The agency lifted the ground stop on Friday evening.

Duffy said investigators have not yet decided who is to blame. “We’re working to determine whether we had incompetence, meaning was it user error or installer error from L3Harris, or did they install a faulty router?” he said. He called it an FAA system that “didn’t meet the moment.”

L3Harris said it takes the issue seriously and is supporting the investigation. The company said it has finished more than 70% of the planned switch from copper to fiber. The routers being replaced are about 25 years old and were due for replacement in 2006.

Airlines Still Recovering

Flight problems continued on Saturday as airlines moved planes and crews back into position. FlightAware data showed more than 5,300 cancellations and nearly 6,300 delays by late afternoon. Friday brought about 9,200 cancellations and 7,500 delays.

Delta, United and American each canceled about 20% of their scheduled flights on Saturday. JetBlue canceled about 40%. Airlines offered waivers so passengers could rebook without extra fees.

Tens of thousands of travelers were stranded at airports. College football teams heading to Saturday games were also affected. Bedford apologized and said operations should return largely to normal by late Sunday.

The White House held an emergency meeting in the Situation Room on Friday. Officials first looked into whether a cyberattack was involved. Homeland Security Secretary Markwayne Mullin later said it was not, and he said it was not linked to Thursday’s Microsoft service disruption.

The FAA spends about $1 billion a year to maintain its copper wire system. Congress has given the agency $12.5 billion for upgrades. Duffy has now asked for $50 billion more for air traffic control and airports, up from his earlier $30 billion proposal.

Friday’s outage was the longest nationwide flight shutdown since the September 11, 2001 attacks. The only other nationwide ground stop since then came in January 2023, when a contractor deleted files by mistake. That stop lasted about 90 minutes and affected 11,000 flights.

The FAA has not yet published a final technical explanation. Its investigation will examine how the router installation disrupted communications across several control centers. Officials said the system could fail again until it is properly upgraded.