FAA says air traffic system stable after ground stop lasting more than four hours

Airlines cancel more than 6,600 Saturday flights after disruption

Officials said they expect airline schedules to fully recover by the end of the day Sunday. The FAA ground stop — the longest flight stoppage in 25 years — began Friday and ended around 8:15 p.m. ET, allowing some domestic flights to take off from U.S. airports.

FlightAware counted more than 6,600 cancellations among 41,000 flights scheduled Saturday. Cirium, an aviation analytics firm, counted just over 1,300 cancellations among more than 26,000 flights scheduled Sunday, about 5.2% of scheduled flights. Before Friday, the average cancellation rate for U.S. departures was 3.4%.

Officials said the U.S. airspace was safe and operational and would recover well ahead of the Thanksgiving travel rush. Bedford said the system was stable Saturday and that several thousand flights were able to fly after the ground stop, but that some 12,000 scheduled flights were ultimately unable to take off Friday.

Bedford offered an apology for stranded travelers and thanked air traffic controllers, pilots and flight attendants for managing the fallout. He said officials were confident the system was operating safely or else they would keep airplanes on the ground.

“We did that out of an abundance of caution,” Bedford said. “I’m sorry that we put you through this, but we did it for the right reasons.”

American Airlines said in a statement Saturday night that some individual flights might still be canceled as it continued working to fully restore its operations, and it urged travelers to check their flight statuses. Airlines are obligated to offer free rebooking on another flight or a full refund if a flight is canceled. Bedford said the FAA was working closely with airlines and that they were waiving all terms and conditions. Some airlines were allowing passengers to rebook if they had travel scheduled Friday or Saturday; others extended the offer to reservations for Sunday or even Monday. Bedford advised passengers to contact their airlines.

The cause traced to routine upgrade work. Duffy said a contractor was replacing a section of the system’s old and discontinued copper wire with new fiber wire in a remote location Friday afternoon, and that such work has been happening across the country and across industries for decades. But on Friday, the router in that location started overloading the air traffic control system and causing intermittent disruptions to communications and radar feeds. When officials couldn’t quickly locate the cause of the overload, they grounded flights nationwide.

Officials stressed that the ground stop was not the result of a system outage or nefarious activity by a foreign actor. Duffy said officials were investigating whether contractor error or a faulty router was the cause. Mullin, the secretary of Homeland Security, said there was no indication the failure was related to a cyberattack and no lives were at risk.

The episode lands against the backdrop of an ongoing air traffic control modernization that began last year after Congress approved $12.5 billion of funding. Duffy and the White House are pushing for $30 billion more to complete the work, and officials said Saturday that about 70% of the copper wire has already been switched to fiber.

A separate Microsoft outage was unrelated to the stoppage, officials said. Microsoft said Saturday that its services were fully restored after a massive outage that took Microsoft services offline Thursday, and federal officials and a company spokesperson said there was no indication the FAA ground stop was related to the disruption. Microsoft says more than 430 million people use its Microsoft 365 apps; users reported Microsoft 365 services including Outlook, Teams and the AI assistant Copilot were interrupted.