The FAA ground stop is over. The flight delays are not

The FAA issued a nationwide ground stop on Friday, Nov. 13, halting departing flights at U.S. airports for more than four hours after communication problems hit air traffic control. The FAA ground stop was lifted that evening, and takeoffs resumed. The delay and cancellation wave did not end with it. On Saturday morning, airlines were still trying to get aircraft and crews back into place, with thousands of additional flights canceled or delayed ahead of the Thanksgiving travel period.

What caused the FAA ground stop?

Transportation Secretary Sean Duffy said Saturday that routine maintenance by a longtime FAA contractor, L3Harris, set off the problem. According to NBC News, Duffy said a contractor switching telecommunications lines at a remote location flooded the air traffic control system, with more than 1,000 connection attempts every four to five seconds as old copper wire was being replaced with fiber. "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?" Duffy said. "We haven't determined what the fault was."

That Saturday account builds on what Duffy said Friday night. In a news conference after the halt was lifted, he said analog telecom switches and routers "got overloaded with data" and that terminal radar facilities "started to have inconsistency in the data from the radars and the communications from airplanes," The Verge reported. The Verge also reported that Duffy and Homeland Security Secretary Markwayne Mullin said "patches" to the existing system sparked the issue. An earlier CBS News report, cited by The Verge, said an update to the air traffic control system's private communications network, operated by L3Harris, caused a system reboot. The Verge said L3Harris had not responded to a request for comment.

The FAA's own first statement was brief and preliminary. It said the agency issued a nationwide ground stop for all U.S. airports "following communication issues impacting multiple Air Route Traffic Control Centers" and that technicians were investigating. Later Friday, the FAA said, "Before clearing flights to resume, we thoroughly tested our systems to confirm they were stable and that operations remain reliable."

Officials said the episode did not appear to be a cyberattack. Speaking Friday afternoon, before the later explanation of the maintenance work, Mullin told reporters there was no reason at that time to suspect a cyberattack or other national security threat, The Verge reported, though he also said no cause had yet been ruled out.

How long did the FAA halt flights, and when will travel return to normal?

The halt itself lasted more than four hours on Friday and is over. Recovery was still underway on Saturday. The Verge reported that the FAA issued the national ground stop at 3:44 p.m. Eastern Time "due to extraordinary circumstances and for reasons of safety," and that officials announced it was lifted at 8:15 p.m. ET.

The cancellation counts moved through the evening and into the next day, and they are not a single official total. FlightAware listed 5,901 U.S. flights canceled and 9,124 delayed as of 8:39 p.m. ET Friday, The Verge reported. CNBC, citing FlightAware, later put Friday's U.S. totals at about 9,000 cancellations and more than 7,000 delays, while noting that some disruptions were due to bad weather. By 9:40 a.m. ET Saturday, CNBC reported, more than 3,700 U.S. flights had been canceled and close to 2,000 delayed. NBC News, citing FlightAware at 9:30 a.m. ET, logged 3,749 cancellations and 1,991 delays, with the worst problems concentrated at Atlanta, Chicago O'Hare and New York's Kennedy Airport.

Those lingering cancellations are what usually follows a long ground stop. Planes were diverted, The Verge noted that some crews ran out of legal time to fly, and airlines had to put aircraft and staff back on their planned routes. CNBC reported that airlines were using a relatively light Saturday schedule and spare planes and crews to catch up, and that around 3 million people would typically be scheduled to fly on a Saturday, according to aviation data firm Cirium.

American Airlines and United Airlines said they were waiving fees for passengers who needed to change or cancel travel because of the disruption, NBC News reported. United said "most flights" would operate as normal but that some issues would remain as it repositioned aircraft and crews. "To our customers: We're sorry for the impact FAA's nationwide ground stop has had on your travel plans," American said. "Our entire team is focused on getting you on your way." Delta said it was offering flexible rebooking and encouraged travelers who could wait to move their flights to Monday, Nov. 16, or later. CNBC also reported that American was offering flight attendants extra pay to pick up trips.

CNBC described the episode as the longest nationwide halt of flights into U.S. airports since the Sept. 11, 2001, attacks. The Verge, citing CNN, said the last nationwide ground stop was in 2023, when the Notice to Air Missions system went down for about 90 minutes, and that the one before that followed the 2001 attacks.

What should travelers and companies watch now?

The practical question is how quickly airline schedules stabilize before Thanksgiving. Duffy said Friday night that recovery would be slow as planes and crews are repositioned, and, according to NBC News, that he was optimistic operations would be ready for the holiday rush: "I think we're going to be back up and operational as we come into the heat of travel during Thanksgiving."

For travelers, the immediate steps are the usual ones after a systemwide outage: check the airline app, use the fee waivers where they apply, and do not assume a Saturday or Sunday seat is a given. For companies with people on the move, the same advice applies, plus a reminder that air traffic control is a single point of failure. A maintenance change on a communications network was enough, officials said, to stop takeoffs nationwide.

Duffy has also pointed to aging equipment as the broader backdrop. The specific fault in this case, by his own account on Saturday, had not yet been pinned down.

Sources

• FAA Statement on Nationwide Ground Stop, Federal Aviation Administration
• FAA ground stop lifted but U.S. flight disruptions continue, CNBC
• FAA lifts nationwide ground stop that blocked takeoffs for hours, The Verge
• Flight disruptions continue after FAA lifts nationwide ground stop, NBC News