Flights at most US airports were held at the gate for over an hour after a computer outage at the Federal Aviation Administration.
Around 7 a.m. ET, the FAA said that flights throughout the U.S. would be grounded until 9 a.m ET. The agency said at 8:15 a.m. ET some flights out of Newark, New Jersey, and Atlanta could resume.
Shortly before 9 a.m. ET, the FAA said flights were starting to resume elsewhere.
"Normal air traffic operations are resuming gradually across the U.S. following an overnight outage to the Notice to Air Missions system that provides safety info to flight crews. The ground stop has been lifted," the FAA said.
President Joe Biden responded to the incident early Wednesday morning.
"I just spoke with (Transportation Secretary Pete) Buttigieg. They don't know what the cause is. But I was on the phone with him" Biden said. "I told them to report directly to me when they find out. Aircraft can still land safely, just not take off right now. They don't know what the cause of it is; they expect in a couple of hours, they'll have a good sense of what caused it and will respond at that time."
The White House said it has "no evidence" of this being caused by a cyberattack "at this point."
As of 10:20 a.m., FlightAware reported 956 cancelations within the U.S.
The FAA said in a tweet that it was working on restoring its Notice to Air Missions System.
“We are performing final validation checks and reloading the system now,” the FAA said. “Operations across the National Airspace System are affected.”
The FAA was working to restore what is known as the Notice to Air Missions System.
NOTAMs used to be available through a hotline but that was phased out with the internet. The alerts span from mundane information about construction at airports to urgent flight restrictions or broken equipment.
All aircraft must route through the system, including commercial and military flights.