Widespread disruption hit the capital's airports, as well as other hubs across the UK, following a technical failure at the NATS control centre in Swanwick yesterday, although the "system has been restored".
A statement from flight safety body Eurocontrol said: "There has been a failure of the flight data computer server at London ACC [area control centre]. Engineers are working on the problem and more information will be given when available."
A Twitter update from from London Heathrow Airport this morning (13 December) read:
Heathrow had warned travellers yesterday: "The earlier problem will cause delays and cancellations to flights for the rest of the day and is likely to have a knock-on effect on some services tomorrow because aircraft and crew will now be out of position.
"Passengers due to depart today and tomorrow should check the status of their flight with their airline before travelling to Heathrow. We are very sorry for the disruption to passengers’ journeys. We have extra staff on duty to help passengers."
London Gatwick Airport confirmed via Twitter that flights were now departing, but subject to delays:
London Stansted airport tweeted that its flights were suspended, as did London City Airport:
The latest update from NATS, the UK-based global air traffic management company, said: "Following a technical fault with the flight data system used by air traffic controllers at Swanwick, NATS can confirm that the system has been restored to full operational capability and a thorough investigation is continuing, to identify the root cause.
Although operational restrictions applied during the failure have been lifted, it will take time for flight operations across the UK to fully recover so passengers should contact their airline for the status of their flight.
"We apologise for the impact that this issue has had, and the delays and inconvenience caused."
If any of your events have been affected by the disruption, tweet @CITmagazine or email firstname.lastname@example.org