Maintenance work to replace aging copper wire at a remote Federal Aviation Administration location that went awry grounded the nation’s air travel system Friday. Cancellations and delays were expected to continue all weekend at Sea-Tac Airport and elsewhere.
Aerospace and defense tech company L3Harris, which owns and maintains the system the FAA uses to control the nation’s airspace, was working on “routine maintenance” to switch old copper wires over to fiber optic cables, Transportation Secretary Sean Duffy said Saturday at his second news conference since the nearly five-hour ground stop on Friday.
That cable replacement work was done at “at least one of FAA’s remote locations,” he continued, and was necessary to upgrade the system from analog to digital.
Travelers continued to face delays and cancellations Saturday as the U.S. air travel system struggles to recover from the nationwide pause in flights.
At Seattle-Tacoma International Airport, 130 flights scheduled for Saturday had been canceled and an additional 170 were delayed as of noon Saturday, according to FlightAware.
It's still not clear exactly what went wrong — whether the new equipment was faulty or it was installed incorrectly — but the router began to flood the FAA’s other routers. The FAA reported over 1,000 connection attempts every four to five seconds.
That data breakdown disrupted air traffic controllers’ communication with aircraft and FAA’s radar systems, prompting the nationwide ground stop, the FAA’s third in 25 years.
“This was an FAA system that didn’t meet the moment, our contractor didn’t meet the moment, or the equipment didn’t meet the moment and caused the outages,” Duffy said.
L3Harris said Saturday it is “supporting the FAA in its investigation to understand the conditions that led to the Nov. 13 ground stop of our nation’s air travel. L3Harris takes the nationwide group stop and its impact on travelers, airlines and air traffic operations seriously.”
Alaska Air Group — which includes Alaska, Hawaiian and Horizon Air, as well as ground support company McGee Air Services — said Saturday morning it had canceled more than 400 flights since the ground stop began. The disruption has so far impacted 37,000 travelers.
“Those cancellations, along with diversions, have put many of our aircraft and crews out of position,” the Seatac-headquartered airline said in a statement. “It will take time for our operations to get back on track through the weekend.”
Delta, which accounts for the second highest amount of Sea-Tac traffic following Alaska, encouraged travelers with flexibility to move their flights to Monday or later. The airline was still working to restore operations Saturday morning and said passengers should “expect delays and additional schedule adjustments as we work to reposition flight crews and aircraft.”
The Port of Seattle, which operates Sea-Tac, told passengers the best way to get their flight status was to check with the airlines.
King County International Airport, or Boeing Field, was also subject to the ground stop but it did not experience any lasting disruptions to service, according to FlightAware. Paine Field in Snohomish County canceled 17 flights Friday and six Saturday.
FAA Administrator Bryan Bedford said airlines still will face delays and cancellations this weekend, but he expects air travel will return to normal by the end of Sunday. “The worst is behind us,” he said at Saturday’s news conference.
The nationwide stop was the first since January 2023, when another key FAA system that sends notices to pilots malfunctioned, and the second one since the Sept. 11, 2001, attacks.
Duffy said again Saturday morning that government officials do not believe the communications disruption was a result of a cyber attack.
Duffy and Bedford told reporters the ground stop was the result of an aging air traffic control system and pushed Congress to allocate more funds to update the system’s hardware and software, echoing the same comments Duffy shared Friday evening.
Bedford said the cable updates that triggered the ground stop were not related to the FAA’s long-term plan to modernize the air traffic control system by the end of 2028.
That plan, which the FAA is executing with Virginia-based tech company Peraton, does call for replacing outdated infrastructure, including radar and telecommunications networks. But the work done by L3Harris was “ordinary course-of-business stuff” to maintain the FAA’s current system, Bedford said.
On Friday, FAA officials said the ground stop was also not related to a new cloud-based air traffic management system rolled out this week. The system — called the Strategic Management of Airspace, Routes and Trajectories, or SMART — uses artificial intelligence to analyze airline schedules, weather, airport capacity and other airspace conditions in an effort to predict traffic jams and identify potential concerns before they impact flight operations.
At the first news conference following the ground stop Friday, Homeland Security Secretary Markwayne Mullin hinted that equipment updates may have been involved in the disruptions. A patchwork of fixes to upgrade some equipment appeared to contribute to the data overload, Mullen said, with “the new equipment and technology … overwhelming the older system.”
U.S. Rep. Rick Larsen, D-Everett, ranking member of House Committee on Transportation and Infrastructure and Rep. André Carson, D-Ind., ranking member of the subcommittee on aviation, said Saturday they will seek more information from the FAA on its funding request and how previous funds earmarked for upgrades to the air traffic control system have been spent.
“This ground stop left the flying public and aviation workforce in disarray and seeking answers that the Trump administration waited hours to share. … Our committee, on behalf of the flying public, will hold the administration accountable for what happened to make sure this chaos does not happen again,” the lawmakers said.
Duffy and L3Harris said Saturday that the FAA and its contractor have replaced nearly 70% of the copper communication wires to high speed fiber.
L3Harris, based in Florida and with locations around the globe, acquired Redmond’s Aerojet Rocketdyne in 2023. In August, it sold a majority stake of the commercial space propulsion and electronics business to private equity firm AE Industrial Partners for $845 million.
©2026 The Seattle Times. Visit seattletimes.com. Distributed by Tribune Content Agency, LLC.
