Sources familiar with the matter say the U.S. Federal Aviation Administration has lifted its nationwide ground stop.
The order had halted all departures across the country after a communications failure, and airlines were allowed to resume operations after the grounding lasted more than four hours.
The communications failure affected multiple air traffic control centers nationwide, and the ground stop was subsequently lifted.
Airlines must now rebuild their schedules, and in the wake of the capacity freeze, delays and cancellations could persist for hours, requiring carriers to reposition aircraft and flight crews.
This marks the third nationwide ground stop in U.S. history.
The FAA has long been plagued by aging air traffic control facilities, and pressure to modernize its systems continues to mount.
The agency initially ordered all departing flights to hold in place under special circumstances and for safety reasons, pending further notice.
Transportation Secretary Sean Duffy said earlier on Friday that the communications failure affected every high-altitude air route traffic control center.
The FAA described the cause as a temporary communications disruption, but the exact reason remains under investigation.
Sources say the FBI has concluded the failure was not caused by a cyberattack or criminal activity.
Investigators are examining whether a software update triggered the outage.
This shutdown is the third nationwide ground stop in U.S. history, following the 2023 failure of the FAA's safety notice system for pilots and dispatchers and the September 11, 2001, terrorist attacks.
The failure comes as the FAA carries out a large-scale modernization of its aging air traffic control infrastructure, for which Congress has allocated $12.5 billion.
Duffy has also requested an additional $3 billion for the project, and the Transportation Department renewed that funding request this week.
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