US ground stop exposes risks in FAA network upgrades

The nationwide US ground stop on 13 November 2026 began during routine work on the Federal Aviation Administration’s telecommunications network. The FAA says a surge in connection attempts disrupted radio communications and radar feeds at facilities nationwide. Transport Secretary Sean Duffy blamed ageing infrastructure, a problem federal auditors have documented for years. The FAA’s preliminary account points to a more specific question: why did a router replacement at a remote site cause disruption on a national scale? 

What triggered the ground stop

FAA contractor L3Harris was installing a router at a radio communications site in El Dorado, Arkansas, as part of work to replace copper lines with fibre. The FAA identified that site and a radar site in Amarillo, Texas, as possible sources of a surge of roughly 1,000 connection attempts every four to five seconds. L3Harris isolated both sites, after which the network stabilised. The FAA also disabled the same function on about 60 similar routers as a precaution.

The FAA’s 15 November update said 17 of its 22 en-route control centres experienced instability, along with several terminal approach control facilities. Some radio frequencies and radar feeds remained available, allowing controllers to communicate with and track aircraft already in the air. Departures resumed at 20:15 EST, and disruption continued into Sunday. The FAA counted approximately 12,462 cancellations on Friday, a total that includes flights cancelled for reasons other than the ground stop.

What the watchdogs had already flagged

The case for replacing ageing equipment is well documented. In 2024, the US Government Accountability Office reported that the FAA had classified 51 of 138 air traffic control systems as unsustainable and another 54 as potentially unsustainable. A September 2026 audit identified a separate problem with the upgrade itself: the FAA had 11,389 individual project schedules for the first phase and no integrated master schedule. The auditors found that installations at the same sites were generally scheduled without coordinating the work to minimise disruption to controllers. An FAA-commissioned safety review had already warned in 2023 about keeping existing systems available during the transition.

Duffy initially blamed Congress for failing to fund a replacement system. Congress had already appropriated $12.5 billion in July 2025 for modernisation, and on the day of the outage, the administration sought another $30.1 billion for airports and air traffic control. The September audit found that the FAA still lacked both a reliable estimate of the programme’s full costs and a coordinated schedule for carrying out its first phase.

What remains unanswered

The FAA and L3Harris are still investigating why the surge began. Duffy raised equipment failure and installation error as possibilities, and the FAA says it has found no indication of a cyberattack. The agency also says it will review when it carries out such work. Its public account has yet to explain what safeguards were in place to contain a fault at either site, or how much capacity backup systems could provide once the disruption spread. Those findings will help establish how much of the failure stemmed from ageing equipment and how much from the way the upgrade was designed and carried out.

Sources: Federal Aviation Administration, U.S. GAO, reuters.com