After a temporary ban on all US domestic flights, the first planes are taking off again at the airports in Atlanta and Newark in the greater New York area.
This was announced by the US Federal Aviation Administration (FAA) via the short message service Twitter.
The FAA is making progress in fixing a computer glitch that caused chaos in US air travel on Wednesday morning.
The disruption caused a system failure that provides pilots and ground staff with important safety information and notifications of disruptions to flight operations.
As a result, the FAA temporarily suspended all US domestic flights.
Landings are not affected.
The reason for the failure is not yet clear, the White House said.
According to reports from the television channel CNN, the White House has not yet assumed a cyber attack.
US President Joe Biden is in contact with Secretary of Transportation Pete Buttigieg.
The FAA announced early Wednesday morning that there had been a major disruption to the "Notice-to-Air Missions" information system.
Technicians are working to fix the problem and the system will be restarted, the FAA said in a first message via the short message service Twitter.
In a further message in the early afternoon, German time, the air traffic control had asked the airlines to suspend all flights within the USA.
The stop should last until at least 9 a.m. (EST) to allow the agency to check the failed information system.
Instructions and information about temporary or permanent changes to the Aeronautical Information Publication, which are important for orderly, safe and smooth air traffic, are transmitted to pilots via the “Notice-to-Air-Missions” system (NOTAM).