Some planes were seen taking off in Houston on Friday evening after the United States Federal Aviation Administration lifted a rare nationwide ground stop.
The over four-hour stoppage, the longest since the September 2001 terrorist attacks, brought all air travel to a halt across the country and stranded tens of thousands of passengers.
This was the first nationwide ground stop since January 2023 when a key FAA computer system malfunctioned.
It was implemented on Friday afternoon after outdated air traffic communications equipment became overloaded with data and began to fail.
Transportation Secretary Sean Duffy said the issue had affected the regional air traffic control centres that direct planes between airports nationwide.
He said air traffic control systems have not been updated because of a lack of Congressional funding and called for $50 billion in upgrades to the system.
Duffy warned that departures would resume gradually and that with some 10,000 flights cancelled, it could take days for airlines to restore normal operations.
