The FAA has ended the ground stop that shut down domestic air travel due to a computer system error.
"Normal air traffic operations are resuming gradually across the United States following an overnight outage to the FAA's Notice to Air Missions (Notam) system that provides safety information to flight crews," the agency said at 8:50 a.m, adding that it continues to look into the cause of the overnight outage.
According to FlightAware, airlines had canceled 832 flights within, into and out of the U.S. today as of just past 9:30 a.m. Eastern time. Close to 4,600 flights had been delayed.
Carriers were urging travelers to the check the airline's website or app for their flights status before heading to the airport.
"Customers may continue to see some delays and cancellations as we work to restore our schedule," said United, which has issued a travel waiver for 11 cities due to the FAA outage. Other carrier tweeted that they are working to minimize customer disruptions.
The FAA's Notam system sends out real-time flight hazards and restrictions to commercial airline pilots. They can relate to abnormal conditions both in the air and at airports.
The outage has already begun drawing heated comments from the travel industry.
In a statement, U.S. Travel Association CEO Geoff Freeman said the outage was a clear sign that U.S. transportation network needs significant 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."