What is NOTAM, the FAA computer system that grounded all US flights? | CNN Business

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A critical Federal Aviation Administration computer system that suffered an outage on Wednesday and briefly halted all U.S. flights is providing airlines with a digital bulletin board of crucial security updates.

The system is known as Notice to Air Missions or NOTAM. Send 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 a safe distance from each other, but it’s another critical tool for aviation safety.

NOTAM messages may include information about lights out on a particular runway, or a tower near an airport that does not have the necessary safety lights in operation, or an air show taking place in nearby airspace.

“It’s like telling a truck driver that a road is closed in front of him. It’s critical information,” said Mike Boyd, an aviation consultant with Boyd Group International.

Although many flights are flown without the need to see any of these warnings, it is important that NOTAM messages reach pilots, who are trained to check them.

The FAA also operates the nation’s air traffic control system, with air traffic controllers using radar to track all aircraft in its airspace and radio communications with their cabins to guide them safely. The computer systems that are the backbone of the ATC system are also known to have gone down. But when that happens, it usually only affects one region of the country, not the entire nation’s airspace.

NOTAM is a national system, so its failure on Wednesday meant that flights across the country were ordered to not take off for a couple of hours before being allowed to fly again shortly before 9am E.T.

If no new problems arise, flights should return to normal soon, although it may take some time to get all the delayed flights on the air. As of 9:30 a.m., the FlightAware tracking service shows 4,600 delayed flights to, from and within the United States, with 827 flights canceled in total. Aviation analytics firm Circium said there had been 23,000 domestic and international flights to or from the United States scheduled for Wednesday.

“By 6 o’clock tonight we won’t even know it happened, I think,” Boyd said.

But if the problem drags on too long, then flight crews who are on standby for delayed flights will run out of time during their duty day. In this case, a delayed flight could become a canceled one if no new crew can be found.

NOTAMS have been around for decades. But until December 2021, it was known as “Notice to Airmen”, although the acronym was the same as it is today.

It was changed to remove the gender term and so that the notices were also sent to drone operators and not just pilots on board airplanes.