A technical problem in Britain's air traffic control systems has caused widespread flight delays and cancellations across the country's airspace.
London's Heathrow airport cancelled 60 morning flights, 20 per cent of flights were delayed at Gatwick, while airports from Dublin to Glasgow also reported problems on Saturday.
"Engineers are working to rectify the problem as soon as possible. But this is resulting in some delays," said the National Air Traffic Service (NATS), which is part owned between the government and a group of airlines.
In a statement, NATS said it was "experiencing some difficulty switching from night time to daytime operation" at its control centre in southern England.
Safety was not compromised by the glitch at Swanwick in Hampshire, it insisted.
"At night, when it's quiet, we can combine sectors of airspace. When it gets busy in the daytime we split the sectors out again. The voice communications system is configured to enable this to happen," the statement said.
"We experienced a technical problem in the early hours of this morning, which means that it hasn't been possible to reconfigure the voice communications system to split out the sectors for the busier daytime traffic in some areas of the UK en route airspace."
NATS added: "Safety has not been compromised at any time, and we sincerely apologise for any inconvenience being caused to passengers."
Daisy McAndrew, a passenger trying to fly from Gatwick to Barcelona for work, told Sky News she had been told it was going to be a "very, very long delay".
"It's quite eerie when I look out of the window to see the tarmac in Gatwick, normally so busy and also the sky above Gatwick which is normally busy - completely static, there's nothing moving," she said.
