L3Harris under investigation after nationwide US aviation ground stop

L3Harris is under investigation following a nationwide United States aviation ground stop that lasted approximately four to five hours on Friday, November 13, 2026. The disruption, which affected 17 of the 22 Federal Aviation Administration (FAA) en route centers, occurred during routine maintenance to replace legacy copper wiring with fiber optic cables. The incident has disrupted more than 20,000 flights and may lead to a total of 16,000 flight cancellations.

Causes of communication instability

The communications instability was triggered when new routers flooded other routers with over 1,000 connection attempts every four to five seconds. This surge caused data instability across the network, although the FAA reported that the incident did not result in a total blackout of the centers. The routers being replaced are approximately 25 years old and were originally scheduled for replacement in 2006.

United States Transportation Secretary Sean Duffy suggested that the cause of the failure could be human error, an installation error, or a defective router. While the investigation is looking into these possibilities, the United States government has ruled out a cyberattack as the cause of the failure. The FAA reported that the system did not meet the moment during the crisis.

L3Harris and infrastructure maintenance

L3Harris is a United States government contractor and serves as the primary provider of the United States air traffic control system. The company has completed more than 70% of the planned conversion from copper to fiber optic communications within the National Airspace System. The FAA currently spends $1 billion annually to maintain the aging copper wire system that is being upgraded.

In a statement issued on Saturday, November 14, 2026, L3Harris said the company is taking the matter seriously and is cooperating with the investigation. The company stated that it takes the nationwide ground stop and its impact on travelers, airlines, and air traffic operations very seriously.

Impact on aviation and markets

The disruption has resulted in significant delays and thousands of flight cancellations across the country. This event marks the first nationwide ground stop since January 2023 and the second since the September 11, 2001, attacks. The FAA has previously faced system failures due to fiber cuts, accidental file deletion, and component melting.

Following the allegations regarding the system failure, L3Harris shares fell by 6% on the electronic stock market. The investigation into the specific cause of the instability continues as officials examine the hardware and installation processes used during the fiber optic upgrade.

Glossary

• Federal Aviation Administration (FAA) — The FAA is a US agency that has adopted the name small unmanned aircraft system (sUAS) to describe aircraft systems without a flight crew weighing less than 55 pounds. It is responsible for approving commercial unmanned aerial system (UAS) licenses on a case-by-case basis.
• National Airspace System — The National Airspace System is the airspace environment where unmanned aircraft are flown. These aircraft must operate under the rules of a community based organization for recreational purposes or 14 CFR Part 107 for commercial operations.
• en route centers — En route centers are facilities within the aviation infrastructure. In the United States, these centers are part of the network managed by the FAA.
• United States government contractor — A United States government contractor is an entity that provides services or products to the government. L3Harris is an example of such a contractor.