F.A.A.’s Main Warning System for Pilots Is Restored After Outage

The Federal Aviation Administration said on Sunday morning that its primary system for sending real-time safety alerts to pilots was operational again after being down for several hours.

“The NOTAM system is online and operational,” the F.A.A. said in a statement, referring to the notification system. “There were no operational impacts in the National Airspace System.”

According to the F.A.A., the system was back online by 11 a.m. Eastern time on Sunday. Despite warnings that the outage could lead to flight delays, there did not appear to be any major disruptions to U.S. air travel.

NOTAM, shorthand for “Notice to Air Missions,” refers to the alert system that the F.A.A. uses to share information about hazards in the air or on the ground with airlines, such as closed runways, airspace restrictions and navigational signal disruptions.

The F.A.A. and Transportation Secretary Sean Duffy said late on Saturday that the alert system was experiencing a “temporary outage.” At the time, the agency said it was using a contingency program to send safety alerts.

The agency said it was investigating the cause of the outage.

The F.A.A. has been in the process of modernizing the NOTAM system, which has gone down before.

In January 2023, a similar failure led to thousands of flight delays, stymying travel across American airspace. The outage would later be traced to human error, after thousands of files were mistakenly deleted from the system by contractors.

The national airspace system of the United States covers an area of more than 29 million square miles, and the F.A.A. provides air traffic service to more than 45,000 flights a day across that area, according to the agency.

Ali Watkins contributed reporting.