Technology
FAA Ground Stop Traced to Router Upgrade, Not Cyberattack
The Federal Aviation Administration ordered a nationwide ground stop of flights at 3:54 pm Eastern Time on Friday, citing a telecommunications outage that affected air route traffic control centres. The stop was lifted at 8:15 pm that evening, but hundreds of flights remained delayed or cancelled, according to aviation analytics firm Cirium. Aircraft already airborne were allowed to continue to their destinations, and international flights were handled on a case‑by‑case basis.
Officials say the outage was caused by a routine upgrade that overloaded antiquated equipment. L3Harris, a contractor, was replacing a section of the system’s old copper wire with new fibre‑optic lines in a remote location on Friday afternoon. The router installed there began to overload the air traffic control system, creating intermittent communications and radar gaps. When the cause could not be located, flights were grounded nationwide to maintain safety.
Transportation Secretary Sean Duffy said the router “flooded” other routers, with 1,000 connection attempts every four to five seconds. The issue affected communications at 17 of the FAA’s 22 en route centres. The Professional Aviation Safety Specialists union said the problem was isolated to two routers updated on Friday, likely in Arkansas and Texas.
The FAA conducted a safety assessment before the work, and the union said its technicians were not involved in the upgrades that led to the stop. Ageing technology and a shortage of controllers have long been concerns for the U.S. air traffic control system. Duffy called for $50 bn in funding to upgrade these systems, up from an earlier request of $30 bn after Congress approved $12.5 bn last year.
White House officials convened an emergency meeting in the Situation Room amid concerns of a cyberattack, but the U.S. government has since ruled out that possibility. FAA Administrator Bryan Bedford said there was “zero evidence of anything nefarious” and “zero evidence of anything AI‑related.”
L3Harris, which performed the upgrade, is the contractor behind the systems upgrade. The company said it has been working in close coordination with the FAA, prioritising safety and reliability, and has completed more than 70 % of the planned conversion from legacy copper wires to fibre‑optic lines. The FAA is conducting additional testing with L3Harris to assess further risks.
Bedford cautioned that it could take time to return to normal operations, noting that crews and aircraft are out of position for 12,000 flights that were lost. Duffy said airlines were expected to restore full schedules by Sunday night. Airlines have issued travel waivers for affected passengers to rebook flights at no cost. Tens of thousands of people remain stranded in airports across the country, and some have faced surge prices for hotels and rental cars as airlines work to resume flights.
Frequently asked questions
What caused the FAA ground stop?
A routine router upgrade by contractor L3Harris overloaded old copper wire with new fibre‑optic lines, causing intermittent communications and radar gaps at 17 of 22 FAA en‑route centres.
How many flights were affected by the ground stop?
The ground stop left hundreds of flights delayed or cancelled, and the FAA reported 12,000 flights were out of position due to the outage.
Did the FAA find evidence of a cyberattack?
FAA Administrator Bryan Bedford said there was zero evidence of any cyberattack or AI‑related activity, and the U.S. government has ruled out a cyberattack.