Dozens of flights have been cancelled and many others delayed after a computer failure at the headquarters of air traffic control company Nats.
For a time there were no flights able to take off or land at some UK airports and, although Nats was able to resolve the problem by around 4pm, delays and cancellations were expected to drag on into the evening.
Transport Secretary Patrick McLoughlin said the disruption was unacceptable.
He went on: “Any disruption to our aviation system is a matter of the utmost concern, especially at this time of year in the run up to the holiday season.
“Disruption on this scale is simply unacceptable and I have asked Nats for a full explanation of this evening’s incident. I also want to know what steps will be taken to prevent this happening again.”
Today’s problem at Nats’s state-of-the-art £700 million centre at Swanwick is by no means the first glitch at the Hampshire centre.
Having resolved the problem, which started around mid-afternoon, Nats said: “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.”
Heathrow said 50 flights had to be cancelled at the west London airport and warned that this figure could rise and that delays could persist. A spokesman added that there could be delays lasting into tomorrow.
Later, Nats said: “We are investigating the cause of this fault but can confirm that it was not due to a power outage.”
Airports as far north as Aberdeen and Edinburgh were hit by the computer problem. Other airports that reported delays included Birmingham, Manchester, Luton and Bristol.
There were also hold-ups at Stansted and Gatwick but these two major south east England airports appeared to have escaped more lightly than Heathrow where the rate of 80 to 90 flights handled every hour means even a comparatively short systems failure leads to severe disruption.
Which? executive director Richard Lloyd said: “The Denied Boarding Regulations provide a means for consumers to claim compensation for delays and cancellations. However if an airline is able to demonstrate the cancellation or delay was due to extraordinary circumstances then they don’t have to pay out.
“Passengers may, however, still be entitled to refreshments, free phone calls and overnight accommodation depending on how long the delay is, how far you are flying and whether the flight is to or from an EU or non-EU airport or on an EU or non-EU carrier.”
Press Association sports reporter Simon Peach, who landed at Heathrow this afternoon after visiting Istanbul said all the people on his plane had been told they could not have their hold luggage back yet.
“There are large queues at baggage reclaim, and there was an announcement that everyone on my British Airways flight could not have their luggage now. The airline will be sending it by courier to people’s homes,” he said.
“This is affecting people flying in as well as flying out and will cost the airlines money – it is not a cheap mistake.”
Several flights due to depart from Bristol Airport were running late this evening but no services have yet been cancelled.