Thousands of flights were canceled or delayed in the United States Wednesday following an hours-long nationwide grounding of departures due to an outage of a key computer system used by pilots.
The Federal Aviation Administration said normal operations were being restored, but the early morning halt created knock on effects that were expected to snarl travel throughout the day.
"Normal air traffic operations are resuming gradually across the US," the Federal Aviation Administration said on Twitter. "The ground stop has been lifted. We continue to look into the cause of the initial problem."
The agency had identified an issue with the Notice to Air Missions system (NOTAM), which provides information to flight crews about hazards, changes to airport facilities and information that can affect flights.
But the outage was creating yet another hellish day for US travelers less than a month after a bad winter storm roiled the system.
"I just learned that my flight was delayed again," Vince Hamilton said at Reagan National Airport near Washington of a planned trip to Chicago. "Then I go to St. Louis, and I have to catch a bus that I'm probably going to miss."
Near 1900 GMT, some 1,200 flights in and out of the United States had been canceled, with more than 7,900 suffering delays, according to flight tracking website Flight Aware, which does not publish data on domestic flights alone.
The difficulties sparked fresh criticism on Capitol Hill and throughout Washington of the FAA, which has had no confirmed administrator since March.
- Cause unknown -
The FAA announced the problem on Twitter at 6:29 am eastern time (1129 GMT), saying it was working to restore the NOTAM system, announcing 50 minutes later that it ordered a pause on all domestic departures until 9:00 am.
Flying experts say the system contains a range of highly relevant details, such as a closed runway to less significant matters, like the presence of a crane somewhere in or near the airport.
About 30 minutes after the FAA lifted the stop order, a screen at Reagan National Airport was overwhelmingly red with flight delays and just a handful of departures.
"Customers may continue to see some delays and cancellations as we work to restore our schedule," United Airlines said shortly after the FAA stop order was lifted, adding it would refund customers who no longer wished to travel.
White House Press Secretary Karine Jean-Pierre tweeted that "there is no evidence of a cyberattack at this point."
"The President directed DOT to conduct a full investigation into the causes. The FAA will provide regular updates," she said, referring to the Department of Transportation.
Transportation Secretary Pete Buttigieg said the probe would uncover "root causes" and point towards "next steps."
Senator Maria Cantwell, the Democratic Chair of the Senate Commerce Committee, also plans follow up.
"We will be looking into what caused this outage and how redundancy plays a role in preventing future outages. The public needs a resilient air transportation system," Cantwell said.
Republican Senator Ted Cruz of Texas called the outage "completely unacceptable," adding that "this incident also highlights why the public needs a competent, proven leader with substantive aviation experience leading the FAA."
The White House last week renominated Phillip Washington as chief of the aviation safety regulator, replacing former head Stephen Dickson, who left office on March 31.
Washington was originally nominated in July, but the Senate did not schedule a confirmation hearing on Washington, with some lawmakers questioning his lack of background in aviation.
Washington served as head of Denver International Airport in 2021 after a long career in the US Army that was followed by other non-aviation transportation posts.
Travel industry officials said Wednesday's crisis points to key vulnerabilities in US infrastructure.
"Today's FAA catastrophic system failure is a clear sign that America's transportation network desperately needs significant upgrades," said US Travel Association President Geoff Freeman.
The halt comes in the wake of a large-scale aviation meltdown in the United States over the Christmas holiday, as a storm brought unseasonably cold temperatures to the majority of the country and caused chaos, with thousands of flights delayed or canceled.
Hard-hit Southwest Airlines canceled more than 15,000 flights over eight days after what it said was a breakdown in its scheduling systems. That mishap is also expected to be spotlighted in congressional hearings.