The U.S. awoke Wednesday morning to a massive and as-yet-unexplained disruption in the national air-travel system triggered by the failure of an obscure but crucial FAA service called Notice to Air Missions, or NOTAMs. The shutdown began at 3:30 a.m. and by 7 a.m. had resulted in the delay of over a thousand flights as the FAA halted the departure of all domestic flights. Planes already in the air were allowed to fly as planned. By 9 a.m., the FAA had managed to restore the system and reported that normal air operations were “resuming gradually across the U.S.,” but significant delays remained widespread.
The disruption came on the heels of a big holiday meltdown that caused Southwest Airlines to cancel more than 15,000 flights amid bad weather and a failure of its scheduling system, and it will no doubt put further heat on Transportation Secretary Pete Buttigieg, who critics say has failed to use his regulatory powers to protect the integrity of the nation’s air-travel system.
NOTAMs, originally called “notice to airmen” and still referred to as such in international aviation, is a system by which pilots are alerted to potential hazards or obstructions they might encounter en route such as runway changes at the destination airport, problems with navigational beacons, or the closure of airspace surrounding a sports game or presidential visit. Pilots receive NOTAMs as part of their standard preflight preparations along with weather and other information that might affect the flight. They can also receive them en route from air-traffic controllers or via automated weather-information broadcasts. NOTAMs rarely concern matters of urgent safety, and it’s entirely possible domestic air-travel could operate safely without it for a day or two, but as a legal matter pilots cannot fly without them.
At 7 a.m., the FAA tweeted that it was working to reboot the system and that “some functions are beginning to come online.” An hour later, it reported that departures had resumed at Newark and Atlanta airports and that departures would begin again elsewhere at 9 a.m. The resumption of NOTAM service did not mean an immediate return to normal flight operations, however, as dispatchers and air-traffic controllers were left to untangle the backlog that had developed over the preceding hours. At 9:30 a.m., FlightAware listed 4,592 flights delayed within, into, or out of the United States and 825 flights canceled, though it was impossible to say how many were directly due to the NOTAM system failure.
It’s still unclear what might have caused the shutdown. At fault could be an inadequately maintained computer system of the kind that contributed to last month’s Southwest debacle or some kind of malicious attack. On Wednesday morning, President Biden told reporters, “I just spoke with Buttigieg … They don’t know what the cause is.” White House press secretary Karine Jean-Pierre tweeted, “There is no evidence of a cyberattack at this point, but the President directed DOT to conduct a full investigation into the causes.”