The US Federal Aviation Administration has issued a national ground stop “due to extraordinary circumstance and reasons for safety” after the agency earlier reported serious air traffic control communications issues.
Shortly before the announcement, the FAA halted traffic in Chicago due to air traffic control issues.
The agency said: “All departing traffic should remain ground stopped until further notice.”
The FAA said international flights will be managed on a case-by-case basis.
The announcement means flights already in the air may land but flights on the ground cannot take off.
This is only the second nationwide ground stop in the United States since the September 11 terror attacks.
The last one was in January 2023, when domestic departures were paused for less than two hours.
The US Transportation Secretary Sean Duffy confirmed it was due to a communication issue affecting all air route traffic control centres.
Mr Duffy said FAA technicians were investigating the issue.
