Acritical outage of a computer system that relays important, time-sensitive information to pilots and airports temporarily grounded flights across North America late on Tuesday night and into the early hours of Wednesday morning.

The Federal Aviation Administration (FAA) said its ‘Notices to Air Missions’ system “failed” on Tuesday night and, as a result, no new NOTAM messages or amendments could be processed.

The short notice continued: “Technicians are currently working to restore the system, and there is no estimate for restoration of service at this time.”

As described by the FAA, the Notice to Air Mission system relays information that is “essential to personnel concerned with flight operations”. NOTAMs are used to convey time-sensitive information quickly, and pilots and airports rely on this system when making route plans.

NOTAMs were previously called Notices to Air Men, but the FAA adopted gender-neutral terminology in 2021.

Some travelers took to Twitter to describe their experiences as flights were grounded in response to the outage. Joshua Caleb Smith said he was “stuck” in Honolulu Airport after a ground stop prevented flights from departing.

One of many flights that were delayed as a result of the outage was United Airlines flight UA505 from San Francisco to Houston, which was originally meant to depart at 11:55 pm on Tuesday but kept on getting delayed until it was eventually canceled.

United Airlines said the flight had to be scrapped because “of airport conditions” that prevented the departure.

The FAA did not immediately comment publicly on the problems affecting the NOTAM system, but a workaround appears to have got flights back in the air – albeit with some delays.