The Federal Aviation Administration issued a nationwide ground stop on Friday afternoon after reporting communication problems affecting "multiple" air traffic control centers.
A ground stop halts flights at their departure point.
"The FAA issued a nationwide ground stop for all U.S. airports following communication issues impacting multiple Air Route Traffic Control Centers," the FAA said.
The agency said in a statement that "FAA technicians are investigating the issue."
Inbound international flights will be managed on a case by case basis, the FAA said.
Nationwide ground stops are extremely rare. In January 2023, the FAA halted flights because of issues with a pilot alert system. Before that, traffic was halted nationwide after the Sept. 11, 2001, terror attacks.
This is breaking news. Please refresh for updates.