FAA ground stop: L3Harris router failure disrupts 12,000 US flights

The Federal Aviation Administration (FAA) expects US flight schedules to return to normal by Sunday evening, November 15, after a nationwide ground stop on Friday disrupted approximately 12,000 flights and triggered thousands of cancellations across major airports.

Transportation Secretary Sean Duffy said the outage originated during routine telecommunications maintenance by contractor L3Harris Technologies. A router involved in replacing copper cables with fibre-optic connections overloaded the FAA’s communications network, interfering with air traffic control systems.

The ground stop lasted more than four hours on November 13, making it one of the most significant nationwide aviation shutdowns since September 11, 2001. Although flights resumed on Friday evening, airlines continued cancelling services throughout Saturday as they repositioned aircraft and crews.

• The FAA suspended departures nationwide after a router malfunction disrupted communications across more than 10 air traffic control facilities.
• L3Harris was conducting a copper-to-fibre network upgrade when the failure occurred. Officials have ruled out a cyberattack but have not established whether the router was defective or incorrectly installed.
• More than 9,000 flights were cancelled on Friday, with thousands more affected on Saturday. The FAA expects recovery by November 15.

FAA Administrator Bryan Bedford expects between 4,000 and 5,000 flight cancellations on November 14, with airlines aiming to restore normal schedules by Sunday night.

What caused the nationwide FAA ground stop?

The disruption began on Friday afternoon when L3Harris Technologies was upgrading telecommunications infrastructure at a remote FAA facility.

The contractor was replacing ageing copper connections with fibre-optic cabling as part of routine maintenance on the FAA Telecommunications Infrastructure (FTI) network.

According to Duffy, a router involved in the upgrade began overwhelming other devices connected to the national air traffic control system.

The malfunction generated more than 1,000 connection attempts every four to five seconds, causing instability across the network that carries voice communications and radar information.

A problem originating at one remote installation spread through the national network, affecting communications used by air traffic controllers to manage aircraft movements.

FAA officials detected intermittent communication failures at more than 10 facilities. Although no air traffic control centre lost all communications, certain radio frequencies and data connections became unreliable.

The agency subsequently ordered a nationwide ground stop as a safety precaution.

Investigators traced the disruption to the remote maintenance location and isolated the affected equipment. Communications systems returned to normal after the problematic connection was disabled.

The FAA also deactivated the relevant function on approximately 60 similar routers nationwide while conducting additional testing.

L3Harris under investigation over router installation

Federal officials have not determined whether the outage resulted from a defective router, incorrect configuration or human error during installation.

L3Harris has operated the FAA telecommunications network for more than two decades, following a contract awarded to its predecessor, Harris Corporation, in 2002.

The FTI network connects more than 4,000 aviation facilities, including control towers, regional control centres and radar installations.

Much of the infrastructure still relies on technology installed decades ago.

Duffy said investigators must establish whether the equipment itself failed or whether L3Harris personnel made an error while carrying out the upgrade.

The precise location of the remote facility has not been disclosed.

Officials also acknowledged that FAA maintenance records are still maintained partly on paper, complicating efforts to identify where work was being performed during the incident.

The agency plans to review its practice of performing network maintenance during daytime operating hours.

A similar failure occurred in 2009 when a Harris Corporation technician incorrectly configured a router during a fibre-optic network transition, disrupting communications at 129 air traffic facilities.

FAA rules out cyberattack and AI system failure

FAA Administrator Bryan Bedford said investigators had found no evidence that the November 13 disruption involved malicious activity, foreign interference or artificial intelligence.

The agency concluded that the failure originated in telecommunications equipment rather than a cybersecurity incident.

The clarification followed speculation about the FAA’s newly introduced SMART system, an AI-powered platform intended to support air traffic management.

Its developer, Air Space Intelligence, said the nationwide ground stop was unrelated to its software or integration with FAA systems.

Bedford said there was no evidence of a cyberattack or AI-related malfunction, identifying the incident as an equipment problem.

The FAA continues to investigate the technical cause of the failure and the measures needed to prevent a recurrence.

Thousands of flights cancelled as US airports recover

The shutdown prevented approximately 12,000 scheduled flights from operating on Friday, including about 9,000 commercial services and 3,000 general aviation flights.

FlightAware recorded more than 9,100 flight cancellations and nearly 25,000 delays on November 13.

American Airlines reported 1,239 cancellations, followed by Southwest Airlines with 1,167, Delta Air Lines with 1,162 and United Airlines with 1,137.

Saturday brought additional disruptions, with more than 4,000 flights cancelled by late morning.

Passengers continued to face long queues, missed connections and baggage delays at major airports.

At Hartsfield-Jackson Atlanta International Airport, stranded travellers spent the night in terminals while waiting for new flights and luggage.

Chicago O’Hare, Los Angeles International Airport and George Bush Intercontinental Airport in Houston also experienced significant disruption.

Airlines must reposition aircraft and crews following the shutdown, meaning flight cancellations can continue even after air traffic control communications are fully restored.

American Airlines warned that additional schedule changes were likely while its operations recovered.

The FAA said the worst of the disruption had passed but acknowledged that normal flight schedules would not return immediately.

FAA network failure renews calls for $50 bn modernisation funding

The incident has intensified scrutiny of the ageing US air traffic control network and the funding required to replace it. The FAA’s telecommunications infrastructure has been identified as a significant operational vulnerability for years.

A safety review commissioned in 2023 described the network as obsolete, while federal investigations have previously documented outages linked to technical failures and configuration errors.

Bedford warned that the system would remain susceptible to disruption until its underlying infrastructure was replaced.

The FAA relies on a single national telecommunications network, leaving multiple backup communication channels exposed to failures affecting the same infrastructure.

Congress approved $12.5 bn for air traffic control upgrades in 2025.

Duffy has requested further funding and now wants approximately $50 bn for a broader infrastructure modernisation programme, including improvements beyond telecommunications.

According to FAA officials, approximately $10.1 bn in additional funding would be required to complete the planned network replacement.

Lawmakers from both parties have called for investigations into the outage and the management of previous modernisation funding.

The House Transportation Committee has pledged to review the circumstances that led to the shutdown, while Senate lawmakers have also sought additional scrutiny.

Can passengers claim refunds after the FAA ground stop?

Passengers whose flights were cancelled are entitled to refunds under US Department of Transportation rules if they decide not to travel and reject alternative transportation.

Airlines are also offering temporary rebooking arrangements, although eligibility varies by carrier.

Delta is waiving applicable fare differences for affected travel between November 13 and 15, provided passengers rebook within its published deadline.

United, Southwest and American have introduced similar flexibility for qualifying flights.

Refunds are available for cancelled flights when passengers decline rebooking, but additional hotel and meal compensation is generally not mandatory for disruptions outside an airline’s control.

Because the shutdown resulted from an FAA telecommunications failure, rather than an airline-controlled problem, carriers are generally not required to provide additional compensation for accommodation or meals.

Some travellers may qualify for reimbursement through travel insurance or credit-card trip interruption benefits. Passengers should confirm their flight status directly with their airline before travelling to the airport.

The FAA expects airlines to restore their regular schedules by the end of Sunday, November 15, although individual flight disruptions may continue during the recovery.