There was major disruption to air travel this afternoon as airspace above London was closed. A glitch at the state-of-the-art UK air traffic control centre headquarters in Swanwick, Hampshire, caused severe disruption. Some activity has now been resumed bu there continue to be long delays.
For a time no aircraft were unable to take off at some of the UK's major airports. Some flights were allowed to land.
It was claimed that airspace over London had been closed but air traffic control company NATS denied this, saying airspace capacity was "restricted in order to manage the situation".
About an hour after the announcement, NATS said the system had been restored and it was in the process of returning to normal.
NATS said in a statement:
"Following a technical failure at Swanwick, the system has been restored. However, it will take time for operations across the UK to fully recover so passengers should contact their airline for the status of their flight.
"We apologise for any delays and the inconvenience this may have caused.
"Further information will be released as it becomes available."
However, flight delays were expected to drag on into the evening.
Affected airports included Heathrow, Gatwick and London City. Heathrow said at least 50 flights have been cancelled and it expected the number to rise.
It also said the problem was likely to have a knock-on effect for flights on Saturday because aircraft and crew will not in the correct positions.
European air control agency Eurocontrol said there had been a computer failure.
It said: "Engineers are working on the problem and more information will be given when available. Only already airborne traffic will be accepted."
NATS (National Air Traffic Services) confirmed there was a technical problem at Swanwick.
It said: "We apologise for any delays and our incident response team has been mobilised.
"Every possible action is being taken to assist in resolving the situation and to confirm the details.
"Further information will be released as it becomes available."
One passenger caught up in the travel chaos was Matt Warren. He tweeted: "Stuck on the tarmac at Heathrow airport. Air traffic control failures. No flights in or out. "
Pilot Chris McGee said the impact would be huge as the closure would hit all airports in London and across the South.
"Friday is a very, very busy time and we are in the peak time," she said.
Manchester airport said it was unaffected by the airspace closure and was ready to accept diverted flights.
The state-of-the art centre at Swanwick has been subject to a number of computer glitches since NATS moved there from its old headquarters in West Drayton in west London in the early part of the last decade.
One of the worst problems was a year ago - on Saturday December 7 2013 - when thousands of passengers were left stranded when hundreds of flights were grounded following a technical fault at the Hampshire centre.
Some passengers make light of the best of a bad situation while they continue to remain grounded:
Stuck on the runway at Heathrow en route to Berlin... but we have beer! And it's Christmas! @BBCLondonNews #Heathrow pic.twitter.com/cES0EHPuCo
— Phil Damerell (@Phil_Damerell) December 12, 2014
Here's what London airspace looks like on a normal day:
Originally published 15.41
