Friday's nationwide ground stop was declared after an error occurred while a contractor was updating an old Federal Aviation Administration telecommunication line, Transportation Secretary Sean Duffy said Saturday.
L3Harris, a long time contractor for the
Federal Aviation Administration, was doing routine maintenance in at least one of FAA's remote locations changing copper wire to fiber, he said. Duffy said the routers in these facilities were manufactured in 2001. These updates have been happening in American institutions for decades, Duffy said.
"Virtually every single institution in America has gone from copper to fiber, from analog to digital," Duffy said. "Just maybe the FAA is the last one to be doing this work because the investments haven't been made, but this is not complicated."
L3Harris did not immediately respond to NPR's request for comment.
Duffy said the FAA is still investigating the exact error that started flooding other routers in the air traffic control system.
"It's pretty straightforward work that we were doing yesterday at, again, a very remote location. So what we're working to determine was whether we had incompetence, meaning was it user error, installator error from L3Harris, or did they install a faulty router?"
Bryan Bedford, the FAA administrator, who joined Duffy at the briefing said there was no evidence of anything nefarious happening or AI-related issues.
Thousands of passengers miss flights
Tens of thousands of passengers across the U.S. are still stranded Saturday after a rare ground stop halted all flights.
The chaos is expected to linger for days.
The aviation system is back online and slowly returning to normal Saturday morning, but delays and cancellations will continue after yesterday's nationwide ground stop, Duffy said in the press briefing Saturday.
"Based on everything that we're hearing from our airline partners, they believe that they'll be able to have full schedule integrity by the close of business on Sunday," Bedford said.
Duffy told reporters Friday night: "I think we're going to be back up and operational as we come into the heat of travel during Thanksgiving."
For about four hours on Friday, thousands of flights at U.S. airports were grounded in one of the biggest disruptions of the nation's air travel system since the terrorist attacks on September 11, 2001.
Nearly 25,000 flights were delayed, and over 9,000 were cancelled on Friday, according to FlightAware, a flight tracking site. The disruption seeped into Saturday morning with more than 4,000 cancellations recorded. That's 14% of flights departing the U.S., according to data from Cirium, which tracks aviation analytics.
Duffy said Friday that air traffic control facilities had experienced "intermittent" outages of their radar and communications systems beginning earlier in the afternoon. Duffy blamed "old switches, old routers" for the failures. Homeland Security Secretary Markwayne Mullin joined Duffy in the White House briefing room and said there was no evidence the issue was due to an attack.
Flight boards at airports across the country Saturday morning continued to be riddled with red cancelled marks. At Tampa International Airport in Florida, people in the main terminal area before security curled up in chairs to grab a wink of sleep.
On Friday night, a flight board at Ronald Reagan Washington National Airport in D.C. showed dozens of flights delayed into the early morning hours or cancelled.
Passengers Erin and Jake Britt spent half the day at the airport in D.C. on Friday. Their plane to Fort Lauderdale, Fla. boarded at 3 p.m. By 5:30 p.m., they were getting off the plane — but they were still in D.C.
"Overall, our plane was definitely annoyed, but reasonable," Erin Britt said, as the couple left the airport at 8pm. "People being upset and asking like, 'Well, how are you not prepared for this?' And it was like, 'Well, no one was prepared.'"
She said neither the pilot nor flight attendants had any more information than passengers."They seem just as in the dark," she said.
The pair decided to cancel their weekend trip, but the night didn't end there. They spent over nine hours overnight waiting on the JetBlue customer service call line to be reimbursed. "I was setting alarms in 20 minute intervals in case I fell asleep," Erin Britt said.
For people who had events or plans over the weekend – the delay added an extra layer of stress. Joe Romano and Maddie Cabana had a cruise leaving Orlando, Fla. Saturday afternoon.
"It was a big eye roll. I mean, I travel a lot for work already, so I'm constantly dealing with flight delays," Romano said. "When this happened, I was just like, 'Of course, it always happens to me.'"
"Just rather inconvenient and frustrating," Cabana added, as the pair contemplated checking their bags or going home. "Hopefully, everything will be fine. It'll all work out. It always does."
And it did – eventually. After their JetBlue flight was ultimately cancelled, they quickly booked another one on Southwest Airlines and made it early Saturday morning.
Others, like Suze DiPietro decided flying wasn't worth it anymore. Her husband drove about four hours down from Ocean City, New Jersey to pick her up in D.C. Luckily, they had friends in the area where they spent the night.
"My husband, my hero, is driving down from New Jersey to come get me," DiPietro said.
Other alternatives included people switching to Amtrak trains as they struggled to get to their destination. Although, even Amtrak's system had a brief outage Friday night.
This was only the second nationwide ground stop since September 11, 2001. The U.S. last issued a ground stop of this scale in 2023, when all U.S. airports were shut down due to an outage in the NOTAM (Notice to Air Missions) system, which alerts pilots and airports of real-time hazards.
That outage prompted fears of a cyberattack, but the FAA later determined the issue was caused when contract workers inadvertently deleted critical files.
The FAA has recently begun rolling out an AI-enhanced software tool known as the SMART system as part of its ambitious overhaul of the nation's air traffic control system. But Air Space Intelligence, the company that makes the tool, quickly dismissed speculation that its product could be connected to the flight disruptions.
"The current ground stop is not based on or a result of the SMART system, any product of ASI or our integration with FAA and ATC," the company said on social media.
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