US Flight Chaos Spills Into Saturday as Thousands Canceled After FAA Ground Stop Blamed on 1980s Technology

WASHINGTON — Airlines canceled thousands more flights Saturday as the U.S. air travel system struggled to recover from a rare nationwide ground stop. The Federal Aviation Administration halted departures across the country for more than four hours Friday after a communications failure that officials blamed on outdated equipment.

By 7:45 a.m. EST Saturday, cancellations for the day were nearing 3,500, according to flight tracker FlightAware. More than 15,000 U.S. flights were delayed or canceled Friday, and more than 12,000 departures have been canceled since the disruption began.

The ground stop was the longest nationwide halt in 25 years, according to The Associated Press. It was only the second nationwide ground stop since the Sept. 11, 2001, attacks. The first was in January 2023, when a failure of the FAA's Notice to Air Missions system grounded departures.

'It got overloaded'

The FAA issued the ground stop at about 4 p.m. ET Friday "following communication issues impacting multiple Air Route Traffic Control Centers," the agency said. It cited "extraordinary circumstances and for reasons of safety."

Officials described the cause as a "telecommunication outage." Transportation Secretary Sean Duffy said the problems began at 3:36 p.m. ET, when air traffic control routers became overloaded with data and began giving inconsistent readings.

"We have old switches, old routers. We use 1980s little copper lines. It's an old system that went down and went down everywhere. It got overloaded," Duffy said at a White House news conference.

"What we have is an incredibly old air traffic control system," he said.

Duffy said the FAA had added new technology to the old system, which overwhelmed it. He said newer equipment installed in recent years was not affected. "It's the old hardware that went down," he said.

Duffy acknowledged that officials were still investigating. "We're still working on the details of what went wrong today," he said.

No sign of cyberattack

Homeland Security Secretary Markwayne Mullin said "it does not appear" the problem was caused by a cyberattack, and that there was no evidence of anyone improperly accessing FAA systems.

Mullin said the ground stop was issued "out of an abundance of caution" and that no flights or lives were at risk. He said officials were looking into incompatibilities between older equipment and new technology being installed.

Officials said the outage was not linked to the FAA's new artificial intelligence-powered air traffic system or to the global Microsoft outage earlier in the week. A company involved in the new system said on social media that the ground stop "is not based on or a result of" its technology.

The FAA lifted the ground stop at about 9 p.m. ET.

Global ripple effect

The disruption quickly spread overseas.

In Europe, departures to the United States from Paris' Charles de Gaulle Airport, Frankfurt Airport and London's Heathrow were canceled or delayed Saturday. At Heathrow, affected flights included American Airlines flights to Dallas and Los Angeles and a British Airways flight to New York's JFK.

In Asia, overnight flights from South Korea's Incheon International Airport to New York, Boston, Detroit, Atlanta, Los Angeles and San Francisco faced delays of up to two hours. Korean Air and Asiana Airlines canceled some U.S. flights on Saturday, then reinstated them once the ground stop was lifted, on later schedules. Japan Airlines temporarily paused check-in for nine U.S.-bound flights before restoring it.

Stranded passengers

The ground stop left travelers stranded across the country during a busy travel period. More than 700 flights were canceled at Chicago O'Hare International Airport alone on Friday, prompting some passengers to rent cars or give up on trips. Professional and college sports teams scrambled for alternate transportation to games.

Airlines warned that recovery would take time because planes and crews were out of position. Delta said it was continuing its operational recovery Saturday and issued a waiver allowing passengers traveling Friday to rebook. United and other airlines also offered flexible travel waivers.

Calls for investigation and funding

Sen. Richard Blumenthal, D-Conn., called for a "prompt, penetrating investigation" into the causes of the ground stop.

Duffy used the briefing to press Congress for more money to modernize the air traffic control system, warning that more disruptions could follow without it. "You will have more of them unless the American people and the Congress tell us to build," he said.

The FAA has said it plans to replace legacy systems at more than 400 facilities nationwide by the end of 2028.

What travelers should do

Airlines advise passengers to check flight status before going to the airport, use airline apps to rebook, and look into waivers that allow free changes. Travelers whose flights are canceled are generally entitled to a refund if they choose not to travel.

Disruptions are expected to continue through the weekend as airlines reset their schedules.