A critical Federal Aviation Administration computer system that went down Wednesday, briefly halting all U.S. flights, is providing airlines with a digital bulletin board of important safety updates.
The system is known as Notice to Air Missions or NOTAM. It sends alerts to pilots to inform them of conditions that could affect the safety of their flights. It’s separate from the air traffic control system that keeps planes at a safe distance from each other, but it’s another important tool for flight safety.
NOTAM messages may contain information about a lights failure on a particular runway or tower near an airport where required safety lights are not working, or an air show taking place in nearby airspace.
“It’s like telling a trucker that a road ahead is closed. It’s important information,” said Mike Boyd, aviation consultant at Boyd Group International.
Although many flights take place without the need to display any of these notices, it is important that NOTAM messages reach the pilots who are trained to look for them.
The FAA also operates the country’s air traffic control system, with air traffic controllers using radar to track all aircraft in their airspace and radio communications with their cockpits to guide them safely. The computer systems that form the backbone of the ATC system have also been known to fail. But when that happens, it usually only affects a region of the country, not the nation’s entire airspace.
NOTAM is a national system, so its failure on Wednesday meant flights across the country were ordered not to take off for a few hours before being cleared to fly again just before 9 a.m. ET.
Barring any new issues, flights should return to normal soon, although it may take some time for all delayed flights to be airborne. As of 9:30 a.m., FlightAware location service shows 4,600 delayed flights to, from and within the United States, with 827 flights canceled altogether. Aeronautics analysis firm Circium said 23,000 domestic and international flights to or from the United States were scheduled for Wednesday.
“Until 6pm tonight we won’t even know it happened I think,” Boyd said.
However, if the problem drags on too long, flight crews standing by to fly delayed flights will run out of time on their duty day. In this case, a delayed flight could become a canceled one if no other fresh crew can be found.
NOTAMS have been around for decades. But until December 2021 it was known by the name “Notice to Airmen”, although the acronym was the same as it is today.
It was changed to remove the gender term and because the communications were then also sent to drone operators and not just to pilots on board planes.