A Federal Aviation Administration (FAA) system failure resulted in thousands of cancellations of flights within the US after the "Notice to Air Missions" (Notam) system crashed on Wednesday morning.
The system alerts pilots and other flight personnel about hazards or any changes to airport services or procedures. Its loss caused the FAA to impose a “ground stop” on departing flights.
However, in a lunchtime update, the FAA said: “Normal air traffic operations are resuming gradually across the US following an overnight outage to the Notice to Air Missions system that provides safety info to flight crews. The ground stop has been lifted. We continue to look into the cause of the initial problem.”
The FAA told airlines to “ground stop” US departures until 14.30 UK time (09.30 Eastern Time).
A Virgin Atlantic spokesperson said: “Due to FAA restrictions, some US departures may be affected by delays and we apologise in advance to affected customers.”
Virgin said VS26 from New York JFK to Heathrow had been due to depart from the US at 13.15 GMT but would be delayed. However, VS91 had departed from Heathrow to Orlando at 12.10 GMT.
A British Airways spokesperson added: "Our flights to and from the US are continuing to operate as planned.”
In total, 21,464 flights were due to depart US airports on Wednesday, providing nearly three million seats, data firm Cirium said. Flight tracking website FlightAware said there were more than 3,700 flights delayed by 08:30 Eastern Time, with more than 640 cancelled.
The Foreign Office updated its travel advice to reflect the situation on Wednesday afternoon. "On 11 January 2023, the Federal Aviation Administration (FAA) confirmed that all US domestic departures had been grounded due to an issue with US flight control systems," said the FCDO.
"As of 0850 ET (1350 GMT) the FAA have confirmed that normal air traffic operations are resuming gradually, but domestic departures may still be affected. You should check with your airline before travelling and monitor the FAA website for live updates."