The Federal Aviation Administration lifted its nationwide ground stop Friday evening, allowing flights to resume after a telecommunications outage halted civilian and military aircraft operations, including at March Air Reserve Base in Riverside.
The ground stop was lifted at about 5:30 p.m., but widespread delays and cancellations were expected to continue affecting air travel.
U.S. Transportation Secretary Sean Duffy said Friday night that aging air traffic control equipment and data-overloaded routers caused the disruption.
“What we have is an incredibly old air traffic control system,” Duffy said at a news conference. “Our routers actually got overloaded with data.”
Duffy said the routers began providing inconsistent data, prompting the FAA to shut down the system as a safety precaution. He said some routers had been replaced, but older hardware failed.
The nationwide order, issued shortly after 1 p.m., impacted military operations at March Air Reserve Base, where a spokesman identified only as a Department of War employee said the FAA’s Notice to Airmen applied to military flights.
The official said Friday afternoon that no aircraft were moving, or would move, “until further notice” from the federal government.
March is home to the U.S. Air Force Reserve’s 452nd Air Mobility Wing, which operates air tankers and cargo and troop-transport aircraft. The aircraft sometimes operate on radio bands not used by civilian pilots and fly military-only airways, but routinely transit civilian airspace.
The FAA said a communications issue affected all 22 Air Route Traffic Control Centers nationwide. The centers coordinate traffic on instrument flight plans, while aviators flying under visual flight rules also routinely seek radar tracking for safety.
Duffy confirmed the ground stop in a post on X shortly after 1 p.m.
“The FAA issued a nationwide ground stop for all U.S. airports following a communication issue impacting all ARTCCs,” Duffy wrote. “FAA technicians are investigating the issue.”
An alert sent to airports nationwide and shared online by the flight-tracking site Flightradar24 said the stop was issued “due to extraordinary circumstances and for reasons of safety.” The alert stated that inbound international flights would be managed on a case-by-case basis.
Palm Springs International Airport advised passengers that flight delays were expected and urged travelers to check their flight status directly with their airlines before going to the airport.
Ontario International Airport said it was monitoring the situation.
According to various reports, localized ground stops were issued at Chicago O’Hare and Midway international airports shortly before the nationwide order because of an equipment outage. It was not immediately clear whether the events were related.
Yahoo News reported that one of its reporters was aboard a United Airlines plane waiting to take off from Los Angeles International Airport when the pilot said the communications problem began at an air traffic control center in Kansas City before spreading nationwide.
The outage occurred one day after the FAA announced an expansion of an artificial intelligence-based flight management system known as SMART, or Strategic Management of Airspace, Routes and Trajectories.
The FAA said the system, initially rolled out in the Washington, D.C., area, was being expanded to all 22 air traffic control centers to reduce delays, cut fuel consumption and improve the travel experience.
It was not immediately clear whether the SMART expansion was connected to Friday’s disruption. Homeland Security Secretary Markwayne Mullin said an investigation would determine whether the system played any role.
Air Space Intelligence, the company that developed and operates the SMART system, said in a post on X that the ground stop was not connected to its technology.
“The current ground stop is not based on or a result of the SMART system, or any product of ASI or our integration with FAA and ATC,” the company said.
Mullin said the problem was a telecommunications outage and not a national security threat.
“There is no reason for the public to be afraid or scared for their loved ones,” Mullin said Friday afternoon.
He said there was no indication the outage was the result of a cyberattack or other “nefarious act.”
Friday’s alert marked only the second time since the Sept. 11, 2001, terrorist attacks that the FAA has issued a nationwide ground stop. The last such stop occurred during a roughly 90-minute span in 2023 when a pilot notification system went down.