A technical problem at an air traffic control centre has led to delays and cancellations at major airports, including London’s Heathrow, Gatwick and Stansted.
Thousands of passengers have seen their flights delayed by a “technical problem” at southern England’s main air traffic control centre in Swanwick, Hampshire.
Airports in the south east of England – the world’s busiest airspace – have been hardest hit, with the knock-on impact disrupting flights across the UK and further afield.
Passengers have complained about a lack of information as they spend hours stuck on planes, waiting to find out if their flights will take off.
Eurocontrol, which coordinates air traffic control across Europe, has said the technical problem will not be fixed until after 5pm.
A spokeswoman at Heathrow, where more than 200 flights have been cancelled, said: “Due to a technical issue with air traffic control, flights from many UK airports, including Heathrow, are subject to delay and cancellation.
“If you are flying today you should check the status of your flight with your airline. We are sorry that passengers have experienced disruption to their journeys.”
Gatwick Airport tweeted: “Due to air traffic control systems issues some flights may be delayed. Please check with your airline.”
There are also reports of delays at Stansted, Manchester, Cardiff, Southampton, Luton, London City and flights to the south from Edinburgh and Glasgow.
British Airways said passengers on cancelled flights would be able to claim a full refund or be rebooked on alternative flights.
The airline said in a statement: “Given that Heathrow is the world’s busiest two-runway airport and Gatwick is the world’s busiest single-runway airport, there will be problems for all airlines as a result of the ATC failures.”
The National Air Traffic Control Service (Nats) apologised for the backlog, blaming an internal phone system issue, and said it had handled 20% fewer flights than usual by midday on Saturday.
A spokesperson said: “In the early hours of this morning, a technical problem occurred at our area control centre at Swanwick.”
“The problem is related to the internal telephone system used by our air traffic controllers.”
“At night, when it’s quiet, sectors of airspace are combined. As it gets busier in the daytime the sectors are split out again and additional control positions are opened to meet the traffic demand.”
“Because of the problem with the internal telephone system, it was not possible to open the additional control positions this morning, resulting in a significant reduction in capacity in some areas of UK en-route airspace.”
“Safety has not been compromised at any time.”
The issue has also affected flights UK-bound flights from Ireland and Europe.
Dublin Airport tweeted: “Technical issue with air traffic control in southern England is causing a delay to some flights to England & continental Europe this AM.”
Daisy McAndrew said she had been caught in the “unholy mess” at Gatwick as she tried to fly to Barcelona for work.
She said: “As ever, staff have been fantastic but they know nothing other than the fact it is going to be a very, very long delay – very frustrating.”
“And also, it’s embarrassing, isn’t it? When you look around a lot of people on my plane are not British, they are flying British Airways, they are probably trying to get back to Spain and they will inevitably be thinking this is something that could have possibly been prevented.”
“It doesn’t show our air traffic control system or our travel system in a good light.”
“I have never heard of an example where every single plane is grounded – 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.”
Mrs McAndrew said the pilot on her flight suggested the delays would cause problems at Heathrow for two or three days.
Alwynne Gwilt, stuck at Stansted, said: “We’ve just been stuck on the tarmac since we boarded the plane – at that point I don’t think they realised quite the extent of the issue.”
“Once we were settled in, they told us there might be a delay of two hours and 45 minutes but we’ve had no updates since then.”
“I understand that safety comes first. Unfortunately you want to make the most of it when you go away for a short getaway, but at the moment we’re only seeing the yellow and blue of the Ryanair planes.”
“You have to question why we had to get on the plane if they had known a little bit ahead of time. Now we’re stuck with no tea, coffee, all those things you would be able to get if you were in an airport.”
Singer Howard Donald was also caught up in the chaos. He wrote on Twitter: “Control tower failure at Heathrow as left me stranded for 2-3 hours at dusseldorf. Anyone know any games besides eye spy?”
Radar engineer Dan Holland said the air traffic computer system runs at around 15% capacity during the night when there are fewer flights and then switches to near 100% during the day.
He said: “It seems that when they have made the switch something hasn’t gone right and the data isn’t being optimised enough for the safety of the passengers and the planes in UK airspace.”
Aviation analyst Chris Yates said passengers due to arrive at UK airports from overseas could find themselves diverted elsewhere.
He said: “There are contingency plans in place whenever this happens.”
“Many of the long-haul flights, coming from China, India, the US and so on, passengers sitting on those planes may find themselves diverted to continental airports.”
“But it’s going to be a long wait for them. When the system kicks back in and starts working, there will be a backlog of flights.”
Travel journalist Simon Calder said the technical glitch was a “disaster”.
He said: “The south-east of England is the busiest airspace in the world. London handles far more passengers than anywhere else including Paris, New York, Tokyo and so on.”
He explained that the lack of spare capacity at airports like Heathrow means things get “very messy, very quickly” and airlines are forced to cancel flights to create firebreaks, which allow the system to keep running.