More than 4,500 domestic flights were grounded on Wednesday due to an outage of the Federal Aviation Administration’s technology used to send safety updates to pilots, writes The New York Times. The technology, called the Notice to Air Missions system, is instrumental in sharing information in the air and planning flights. 

While the flights are up and running again, the cause of the outage is still unknown. There seems to be “no evidence of a cyberattack at this point,” per White House Press Secretary Karine Jean-Pierre, however, President Biden has called for an investigation by the Department of Transportation.

Rep. Rick Larsen (D-Wash.), top Democrat on the House Transportation and Infrastructure Committee, said the outage “begs the question about the current state of the technology infrastructure at the FAA.” At the same time, the FAA has not had a proper leader since March because Biden’s nomination was not confirmed by the Senate in 2022. 

The FAA failure has caused mass disruptions, sparking frustration. “This is unheard of,” remarked Michael McCormick, a former FAA official. “The action that the FAA had to take in grounding all the flights makes it even more significant.” He added that this scale of grounding hasn’t happened since the attacks on Sept. 11, 2001, writes The Washington Post. 

Secretary of Transportation Pete Buttigieg has announced that the DOT will look for the root causes of the failure.