The Federal Aviation Administration (FAA) has lifted a pause on all domestic flight departures early Wednesday after a computer system outage sparked widespread delays.
The FAA issued an advisory just after 4 a.m. ET saying that technicians were working to address the problem. United Airlines tweeted that the issue was with the FAA’s Notice to Air Missions (NOTAM) system, which sends out real-time flight hazards and restrictions to all commercial pilots, and that it was temporarily delaying all domestic flights.
The FAA said at 6:30 a.m. that it was performing its final validation checks and reloading the system.
The agency then said at 7:19 a.m. that it was still working to fully restore the system and ordered airlines to pause all domestic departures until 9 a.m. “to allow the agency to validate the integrity of flight and safety information.”
The FAA also tweeted at 8:15 a.m. that it was making progress in restoring the system. It said departures at Newark Liberty International Airport and Hartsfield-Jackson Atlanta International Airport were resuming as a result of air traffic congestion and reiterated that departures at other airports should resume at 9 a.m.
The agency said at 8:50 a.m. that the ground stop was lifted and normal air traffic operations were gradually resuming across the country. It said it will continue to look into the cause of the issue.
All commercial and military flights are required to use the system.
The agency said operations across the National Airspace System were impacted.
Information from NOTAM can be as long as 200 pages and mention runway closures, bird hazards and construction obstacles, according to Reuters.
The flight-tracking website FlightAware reported that more than 5,000 flights within, into or out of the United States were delayed as of just before 10 a.m. Almost 900 flights had been canceled.
More than 21,000 flights were booked to depart airports in the U.S. on Wednesday, Reuters reported.
Transportation Secretary Pete Buttigieg tweeted that he had been in touch with the FAA regarding the glitch. He later said that the NOTAM system had been fully restored.
President Biden said he had spoken to Buttigieg about the situation with the FAA but that the cause of the issue was unknown. He said flights could still land safely but not take off while the system was dealing with the issue.
He also said he told Buttigieg to report directly to him when the cause of the outage was discovered. He said the FAA would have a “good sense” of the cause in a couple hours.
White House press secretary Karine Jean-Pierre tweeted that there was no evidence of a cyberattack being responsible for the technical issue at that point, but Biden has directed the Transportation Department to conduct an investigation into the cause.
Most of the delays on Wednesday have been for flights on the East Coast.
CNN noted that some airlines might be able to operate without information from NOTAM.
Geoff Freeman, the president and CEO of the U.S. Travel Association, which advocates for the various components of the travel industry, said in a statement that the FAA’s “catastrophic” system failure is a “clear sign” that the country’s transportation network needs major upgrades.
“Americans deserve an end-to-end travel experience that is seamless and secure,” he said. “And our nation’s economy depends on a best-in-class air travel system. We call on federal policymakers to modernize our vital air travel infrastructure to ensure our systems are able to meet demand safely and efficiently.”
NBC reported that several airports outside the United States, including Gatwick Airport in London and Frankfurt Airport in Germany, were able to continue their operations without interruption.
Stock prices for U.S. airlines also fell Wednesday during premarket trading, according to Reuters. Southwest Airlines fell 2.4 percent, while Delta, United and American dropped about 1 percent.
The stock prices for several of these airlines rose upon the start of trading.
The FAA computer outage comes a couple weeks after issues with Southwest’s scheduling system forced the airline to cancel thousands of flights ahead of New Year’s weekend, one of the busiest travel weekends of the year.
The cancellations led to federal scrutiny, with the Transportation Department pledging to look into the situation and calling the rate of cancellations “unacceptable.”
The Associated Press contributed to this developing report.