The Federal Aviation Administration (FAA) lifted a nationwide ground stop on Friday after an hours-long telecommunications and radar outage disrupted air travel across the United States. While departures have resumed, officials warned that lingering delays and cancellations will continue to affect passengers.

The disruption began after federal officials issued a ground stop due to safety concerns stemming from data inconsistencies in radars and communication centers. Transportation Secretary Sean Duffy blamed the incident on outdated, analog air traffic control technology and overloaded routers, while Homeland Security Secretary Markwayne Mullin stated there was zero evidence of a cyberattack or any threat to the US.

Data firm Cirium estimated that roughly 1.5 million people were stranded by the cancellations, which also prompted international disruptions, including temporary suspensions of US-bound flights across Europe and Asia. Officials noted that returning the aviation network to normal operations will take time, and urged Congress to fund system upgrades to prevent future incidents.