Airlines resumed flights after a system outage led U.S. authorities to temporarily ground planes nationwide early Wednesday, a dramatic disruption to the air-traffic system expected to cause ongoing delays and cancellations.
The Federal Aviation Administration said normal air traffic operations were “gradually” returning as it lifted the ground stop shortly before 9 a.m. Eastern time. The disruption stemmed from problems with the Notice to Air Missions system, or NOTAM, which conveys advisory information essential for flight operations.
The massive system failure is one of the most significant in recent decades for the FAA and comes after a year of tests of the nation’s air system as the return from COVID-19 stressed airlines and air-traffic operations.
Disruptions are likely to ripple through the aviation system for hours. The FAA imposed multiple airline-specific halts to flights as it works with carriers on restoring their operations. Based on an “airline request,” for example, the FAA stopped some departures for Delta Air Lines Inc. from Boston, the agency said in an advisory just before 9 a.m.
Carriers including United Airlines Holdings Inc. and Southwest Airlines Co. said travelers should expect schedule changes, including delays and cancellations, even as flight operations began resuming. Flight-tracking website FlightAware showed 4,948 delays for US flights at 10:05 a.m.
United offered waivers to affected passengers, letting them rebook travel without having to pay a difference in fares, subject to certain conditions.
The grounding potentially could affect more than 2 million passengers booked on 19,621 domestic flights across various airlines, according to aviation data provider Cirium. That doesn’t include travelers on 1,843 international flights that were set to arrive in the U.S. Wednesday.
The computer system that shares the notices to pilots, airlines and other users began developing problems late Tuesday night and had to be completely taken down in the early hours of Wednesday, said a person familiar with FAA’s actions who asked not to be identified discussing the situation as it develops. FAA technical workers have been troubleshooting the system since then, the person said.
There was no indication that the outage affected the FAA’s ability to track and guide aircraft, or that it caused any safety incidents.
By early Wednesday, passengers due to fly domestically began reporting delays on social media, and United said it would temporarily ground flights.
President Joe Biden was briefed on the situation by Secretary of Transportation Pete Buttigieg, the White House said Wednesday in a tweet. The president ordered a full investigation, but there is “no evidence of a cyberattack at this point.”
“They don’t know what the cause is,” Biden told reporters.
The issues drew the attention of Congress, which is set to update legislation laying out agency policy this year.
“We will be looking into what caused this outage and how redundancy plays a role in preventing future outages,” Sen. Maria Cantwell, a Washington Democrat, said in a statement. Cantwell is chairwoman of the Commerce, Science and Transportation Committee that oversees FAA.
Airline stocks erased their premarket declines with the S&P Supercomposite Airlines Index up 0.9% as of 9:53 a.m. in New York. All 10 U.S. carriers in the index traded higher.
The biggest European airlines said they were largely unaffected by the disruptions, with flights from British Airways, Air France and Deutsche Lufthansa AG operating normally even as domestic U.S. flights were halted, the carriers said.
Given the early hour of the disruption in the U.S., international flights were either still on the ground or nowhere near U.S. air space, giving pilots more turnaround time to react.
The NOTAM system provides airlines with real-time safety information for flight planning. The information conveyed on NOTAM can be as basic as airport weather and active taxiways or as complicated as temporary airspace closures due to a space launch or presidential travel. Pilots at all stages of training and experience are drilled in relying on the data.
The new disruptions follow closely on a December operations meltdown at Southwest that forced it to cancel more than 16,700 flights and drove the airline to a fourth-quarter loss.
And in 2019, entry for people arriving at airports across the U.S. descended into chaos after a Customs and Border Protection IT system failed.