It’s unclear what happened to the system or when it will be restored.
WASHINGTON — A critical system used by U.S. airlines appears to have gone offline Tuesday night, stopping all flights from taking off and leading to nationwide delays.
The Federal Aviation Administration, which is responsible for air travel regulations, confirmed through an advisory that its “NOTAM” system went offline shortly after 11 p.m. Eastern.
The NOTAM system is designed to provide pilots and air traffic controllers with critical information as it develops, including changes in weather or conditions at a certain airport.
The information in NOTAM advisories can be hundreds of pages for some flights, containing details about runway closures, bird hazards or low-altitude obstacles in a flight path.
It’s unclear what happened to the system or when it will be restored.
“Technicians are currently working to restore the system and there is no estimate for restoration of service at this time,” an advisory from the FAA to pilots said.
The FAA said in a statement that it was working to restore the system, and that operations across the National Airspace System were affected.
United Airlines said it was temporarily delaying all domestic flights because of the outage.
“The FAA system that sends out important real-time flight hazards & restrictions to all commercial airline pilots – Notice to Air Missions (NOTAM) – is currently suffering a nationwide outage,” the airline said in a statement. “United has temporarily delayed all domestic flights and will issue an update when we learn more from the FAA.”
On the FAA’s website for the NOTAM system, a message warns users that recent entries may not appear.
“Due to system processing delays, recently entered NOTAMs may not be displayed,” the message reads.
NOTAM messages issued before the outage were still visible Wednesday morning.
More than 760 flights were delayed within, into or out of the U.S. Wednesday morning, according to flight tracking website FlightAware. The website did not cite the NOTAM outage as a factor in the unusually high number of delays.
The industry-wide problem comes less than a month after thousands of flights were canceled or delayed after Christmas, when Southwest Airlines faced major delays due to logistical and tech issues during a winter freeze.