What to know about flights after the U.S. nationwide ground stop

Officials assured passengers that the U.S. airspace was safe and operational after a nationwide ground stop that was initiated out of caution caused massive travel disruptions.

The longest flight stoppage in 25 years lasted more than four hours and ended around 8:15 p.m. ET Friday, allowing some domestic flights to take off from U.S. airports.

Of the 41,000 flights scheduled Saturday, more than 6,400 had been canceled by Saturday night, according to FlightAware. More than 800 flights scheduled for Sunday were canceled, it said.

But officials said the air traffic control system was operational and expected airline schedules to fully recover by the end of Sunday, smoothing out ahead of the Thanksgiving travel rush.

Secretary of Homeland Security Markwayne Mullin said there was no indication the failure was related to a cyberattack and no lives were at risk.

Here’s what to know:

Flights have resumed but the disruption continues

The system was stable Saturday after Friday's massive disruption, Bedford said. Several thousand flights were able to fly after the ground stop, but ultimately, some 12,000 scheduled flights were unable to take off Friday, he said.

Officials acknowledged the disruption but said safety is paramount.

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

Airlines remove change fees for affected passengers

Airlines are obligated to offer free rebooking on another flight or a full refund if the flight was canceled.

Bedford said the administration was working closely with airlines and said they were waiving all terms and conditions.

Some airlines were allowing passengers to rebook if they had travel scheduled for Friday and Saturday, while others extended the offer to those who had existing reservations for Sunday and even Monday.

Bedford advised passengers to contact their airlines for information.

The system was overloaded while part of it was being upgraded

A contractor had been working on replacing a section of the system’s old and discontinued copper wire with new fiber wire in a remote location on Friday afternoon, Secretary of Transportation Sean Duffy said Saturday. That kind of work has been happening across the country and across industries for decades, he said.

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 they couldn’t quickly locate the cause of the overload, they decided to keep flights grounded nationwide.

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

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.

The air traffic control modernization 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. About 70% of copper wire has been switched to fiber already, officials said Saturday.

Microsoft 365 was one of many major web service providers that reported outages Thursday afternoon.

The Microsoft outage was unrelated to the stoppage

Microsoft said Saturday that services were fully restored after its own massive outage this week. There was no indication that the FAA ground stop was related to the service disruption that took Outlook and other services offline Thursday, according to a spokesperson for the company.

Over 430 million people use Microsoft 365 apps, Microsoft said on its website. Problems started appearing around midday Thursday in the U.S. Users reported that Microsoft 365 services, including Outlook, Teams and AI assistant Copilot, had been interrupted.