NATS, Britain's national air traffic body, says the computer problem that touched off troubles in the system has been fixed and it is in the process of returning to normal operations.
The agency says "we apologize for any delays and the inconvenience this may have caused."
London's airspace was closed Friday afternoon due to what authorities said was a computer failure at one of Britain's two air traffic control centers.
Officials at London Heathrow Airport said there was a power outage at the NATS control center in Swanwick, England. NATS controls all of British airspace from two centers, one in Swanwick and another in Scotland.