Flights in southern England have suffered minor delays because of air traffic control computer problems.
Nats, the national air traffic control body, said UK airspace was not shut, nor were all flights in and out of the UK suspended - as one airport had said.
The problem was apparently caused by a "rogue flight plan", resolved by a re-boot of the computer system at Nats' Swanwick, Southampton, control centre.
Operations were returning to normal by lunchtime, Nats said.
Outbound flights were by then being delayed by no more than 20 minutes.
Nats said: "Operations are now returning to normal and we are working with the airports, airlines and Eurocontrol (the European air traffic management body) to clear the backlog of flights to ensure disruption is kept to a minimum.
"We regret any inconvenience this technical problem has caused, however our first priority will always be the safety of the flying public."
Jersey Airport had tweeted just after 10:00 BST on Tuesday that the computer failure at Swanwick had "resulted in the temporary suspension of all flights in and out of UK air space."
In an update 25 minutes later, the airport said there was "once again movement in UK skies. However, some delays may result."
The airport said passengers could check-in as usual.
Flights were also delayed at East Midlands Airport and Southampton Airport.
Southampton Airport suffered delays in the morning, but by 14:00 BST said there were "a few short delays" although passengers could check-in as usual.
A spokeswoman for Gatwick Airport earlier said "there are minor delays particularly with flights to Jersey, where the airspace issue is happening."
She said flights from Europe could be delayed by the restrictions placed around Jersey's airspace.
Low-cost operator Easyjet said there were no delays or flight problems.
Heathrow Airport, the UK's largest hub, had delays of 20-30 minutes at one point. British Airways said all its flights were operating as scheduled.
Nats provides air traffic navigation services to aircraft flying through UK controlled airspace and at several UK and international airports. Its website said it handled 7,086 flights on Monday.