The FAA announced shortly before 9 am ET that it would allow normal air traffic operations to resume, following an outage of its Notice to Air Missions System, which sends notifications to pilots about flight restrictions, hazards and broken equipment.

The latest: Transportation Secretary Pete Buttigieg confirmed on Twitter that the "safety system affected by the overnight outage is fully restored" and that efforts were underway to determine what caused the outage.

The FAA said it would allow flight departures to resume from Hartsfield–Jackson Atlanta International Airport and Newark Liberty International Airport at 8:15 am ET "due to air traffic congestion in those areas," but noted that they "expected" all other departures would resume at 9 am.

President Biden told reporters on Wednesday morning that he had spoken with Buttigieg about the outage and asked that he "report directly to me when they find out" the cause.

"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," Biden said.