A Federal Aviation Administration warning system outage could lead to “residual delays” on Sunday morning, Secretary of Transportation Sean Duffy wrote on X.

The FAA is working to restore the system. In the meantime, the agency has activated contingency systems to allow flight operations to continue.

“The primary NOTAM system is experiencing a temporary outage, but there is currently no impact to the National Airspace System because a backup system is in place,” he wrote on X, 

“The (FAA) is working to fully restore the system, and there may be some residual delays tomorrow morning,” he also wrote. “We are investigating the root cause and we will provide updates.”