US ground stop halts flights for four hours due to router malfunction

A nationwide ground stop in the United States halted departures from the continental United States for over four hours on November 14, 2026. The disruption occurred because a router flooded the air traffic control network with over 1,000 connection attempts every four to five seconds. This malfunction happened during a telecommunications upgrade involving a transition from copper to fiber optic cables.

Technical causes and investigation

The technical failure occurred while contractor L3Harris was performing a copper-to-fiber optic cable upgrade at a remote facility. This specific malfunction caused the router to overwhelm the network with connection attempts. Transportation Secretary Sean Duffy stated that investigators are currently determining whether the malfunction resulted from contractor error or faulty equipment.

Federal authorities have addressed concerns regarding the nature of the outage. FAA Administrator Bryan Bedford stated that there is no evidence of artificial intelligence or cyberattack involvement in the outage. Administrator Bryan Bedford also noted that the worst of the disruption is over and the system should return to normal by Sunday night.

Impact on flight schedules

The scale of the cancellation was significant for the aviation industry. According to Cirium, more than 8,200 flights were canceled on November 14, 2026, which represents over 31% of all scheduled flights for that day. This event was the longest nationwide ground stop since the bans following the September 11, 2001, attacks.

The disruption continued into the following day, though reports on the exact scale of cancellations on November 15, 2026, vary. Cirium reported that more than 3,000 flights were canceled on that date. However, FlightAware reported over 3,500 cancellations and over 2,000 delays on November 15, 2026.

The disruption also caused localized issues for specific carriers. A ground stop was issued specifically for United Airlines flights at Chicago O’Hare International Airport during the event.

Infrastructure and modernization context

The telecommunications upgrade being conducted by L3Harris is a separate effort from the $12.5 billion air traffic control modernization programme. L3Harris reported that the company has completed more than 70% of the planned conversion from copper to fiber.

The incident occurred within a broader context of national infrastructure discussions. President Donald Trump previously requested $30.1 billion for infrastructure upgrades across the country.

Glossary

• fiber optic cables — Fiber optic cables are used to carry commands to a remote-controlled camera head and bring high definition signals back to a control station. They are also used to forward commands from a pilot to winches via software.
• L3Harris — L3Harris Technologies, Inc. is an American technology company, defense contractor, and information technology services provider. The company produces products for various sectors, including command and control systems, wireless equipment, and avionics.
• FAA — The FAA is a United States federal authority. It is capable of issuing Special Airworthiness Information Bulletins (SAIB) and supporting the National Transportation Safety Board (NTSB) during investigations.
• United Airlines — United Airlines is an American scheduled airline based in Chicago. It is a founding member of the Star Alliance and includes subsidiaries such as United Express and United Cargo.