The government has been working to overhaul the outdated technology that air traffic controllers rely on since Congress approved $12.5 billion for the project last year. Miles of old copper wires have been replaced with fiber optic lines, and old radio systems are gradually being replaced at airports across the country.
The stop was the first nationwide grounding since January 2023, when a key FAA computer system malfunctioned, and the second since the aftermath of the Sept. 11 attacks.
The FAA had grounded all flights nationwide Friday afternoon, sending hundreds of aircraft off their planned paths and leaving airlines to rebuild schedules from scattered aircraft and crews.
Even with the order lifted, airlines will not be able to return to normal operations immediately because so many of their planes and crews are out of position.
As of 7:05 p.m. EST, 670 flights had been sent back to the airports where they originally took off, while 157 were redirected to a different airport, according to Cirium, an aviation analytics company.
At least 827 flights were diverted as a result. Effects continued after 4 p.m. EST, raising the likelihood of more cancellations and diversions.
The consequences were profound, disrupting potentially thousands of planned flights through at least late Friday night and upending travel plans for passengers.
International flights were being handled on a case-by-case basis, according to Mullin, with some seen taking off Friday evening.
Friday's ground stop was different from the one after Sept. 11 because planes were not being told to land immediately and pilots likely were able to communicate with ground controllers at airports, Arroyo said.
Arroyo said the priority was clear:"And not put them in the air where you're going to risk not being able to communicate with them.".
"We did see them taking luggage off our plane and others, so we're assuming it's going to be a pretty substantial delay,"Curtis said.
NBA, NHL and college teams were left stranded as they tried to reach their destinations. Cargo flights were also delayed by the ground stop.
FedEx, the world's largest cargo airline, said it is prepared to activate contingency plans to keep any possible disruptions at a minimum. U.S. airlines move about 61,000 tons of goods, from letters to packages, to and from more than 220 countries daily, according to the industry trade group Airlines for America.
Mullin had said investigators will look at whether there is any link to the FAA's nationwide rollout of a new artificial intelligence system to help identify problems and reroute planes.