Image source, Getty Images

Wizz Air has branded air traffic control provider Nats "simply not fit for purpose in its current form" after a technical issue caused hundreds of cancelled flights.

In a statement the airline says it is "extremely disappointed" that "another Nats technical failure" has caused widespread disruption.

"A critical national infrastructure provider should not repeatedly bring the aviation system to a standstill," it says.

It says "urgent reform is needed" and that airlines, passengers and airports "cannot continue to bear the consequences of recurring system failures".

"We sincerely apologise to affected passengers, but today’s disruption originates from the UK air traffic control system and is entirely outside Wizz Air’s control," the statement concludes.

Nats declined to comment on Wizz Air's statement when contacted by the BBC.

Air traffic control provider Nats says recovery from its system issue that has caused widespread disruption is taking "longer than we had hoped".

"Our system issue is now resolved, we are operating normally and working as hard as possible to clear the backlog of flights," it says in a post on X.

"We are truly sorry for the ongoing flight disruption. We know this is hugely frustrating and apologise unreservedly. Passengers should continue to check with their airline."

Image source, Emma Chun

Emma Chun is currently tucking into her British Airways starter on the Heathrow tarmac after her flight was cancelled, but passengers aren’t yet able to get off the plane.

She says the flight was due to take off for New York at 13:20 BST, but all flights were grounded before the plane was given clearance to take off - with passengers since being told the flight had been cancelled.

Emma was still on the plane at 18:30.

"We can’t get off the plane as there’s no steps available so they’ve just served our starters," she says, adding that cabin crew have been able to tell passengers very little.

Emma adds that British Airways have instead booked them on an alternative flight tomorrow, via Copenhagen, arriving in New York on Thursday evening.

"We were due to fly to Buffalo for the day on Thursday to go to Niagra Falls so it means we would also miss that," she says.

Faye Hawker
Live reporter

So far this afternoon, at least 22 flights which were due to land at Heathrow have been diverted to other UK and European airports. They are:

15:10 Finnair 1335 Helsinki to Heathrow diverted to Stansted

15:25 BA268 Los Angeles to Heathrow diverted to Manchester

15:35 BA381 Tirana to Heathrow landed at Gatwick

15:45 BA008 Tokyo to Heathrow diverted to Manchester

15:45 SQ 308 Singapore to Heathrow diverted to Paris

15:45 BA625 Tivat to Heathrow diverted to Gatwick

16:00 AM007 Mexico City to Heathrow diverted to Paris

16:00 TK1931 Istanbul to Heathrow diverted to Birmingham

16:05 BA274 Las Vegas to Heathrow diverted to Gatwick

16:10 EK031 Dubai to Heathrow diverted to Birmingham

16:15 VS301 Delhi to Heathrow diverted to Stansted

16:20 NH211 Tokyo to Heathrow diverted to Stansted

16:30 CI081 Taipei to Heathrow diverted to Frankfurt

16:40 TK1971 Istanbul to Heathrow diverted to Brussels

16:45 BA717 Istanbul to Heathrow diverted to Luton

16:55 BA062 Nairobi to Heathrow diverted to Stansted

17:00 BA 689 Santorini to Heathrow diverted to Stansted

17:35 VS 024 Los Angeles to Heathrow diverted to Manchester

17:40 BA705 Larnaca to Heathrow diverted to Manchester

17:45 6E001 Mumbai to Heathrow diverted to Amsterdam

18:15 BA198 Mumbai diverted to Amsterdam

18:40 BA238 Boston to Heathrow diverted to Glasgow

Katy Austin
Transport correspondent

An airport source says Nats are now releasing small numbers of aircraft as “trials” at various airports, with a view to ramping up to more regular flights.

Charlotte Simpson
Reporting from Gatwick Airport

I'm at Gatwick and was due to be on the 17:15 flight to Bari, Italy, as I'm due to get married In Puglia on Saturday.

I’ve got my wedding dress with me, I’ve got my fiance with me, but sadly we are not going to be going anywhere tonight.

Our flight is among those that have been cancelled this afternoon because of this disruption with air traffic control.

It's pretty chaotic at the moment, people have just been wondering around looking for help - but from what we've seen they've just had to wait around to be told over the public address system - like us - that their flight is cancelled.

Everyone has been rushing on the phone, trying to call various airlines to try and get re-booked.

Luckily our wedding isn't until Saturday, so we do have a bit of time.

But it isn't the tranquil start to our wedding celebrations that we had imagined unfortunately.

Manish Pandey
Reporting from Malta International Airport

I’m at Malta International Airport, where my flight home to London Gatwick has been cancelled.

The departures board initially showed “delayed” to all UK-bound flights when we arrived, before changing the 21:30 BA flight to cancelled.

The official at the British Airways counter has told us all flights to the UK have been cancelled because of the air traffic issues.

There are a significant number of travellers heading home to the UK.

We’ve been told that accommodation is being worked on, and we will be told through the BA app what the next steps are.

There is frustration from lots of passengers, and the coffee shop in the airport is filling up quickly with exhausted travellers.

For now, the wait continues.

Image source, PA Media

British Airways says it has been informed by the air traffic controller that the "fault has been resolved" but due to the severity of the issue, there will be a "significant knock-on impact for customers and colleagues".

A spokesperson for the airline says it was forced to cancel or divert more than 100 flights this afternoon, "inconveniencing tens of thousands of customers".

This incident was "entirely out of our control and incredibly frustrating for our customers and colleagues," it says, with aircraft and crews ending up out of place.

"We ask customers whose flights have been cancelled not to travel to the airport and to bear with us if they’re trying to get in touch, as our call centres are incredibly busy at the moment.

"Customers due to travel today or tomorrow are able to make changes to their booking on ba.com," it adds.

Theo Whyte
Reporting from Gatwick Airport

There is a long queue snaking back from the service desk at Gatwick airport.

People are frantically checking departure screens and their phones for updates. Others are calling airlines in an attempt to find alternate arrangements.

At the airline check-in desks, passengers are queuing up in front of empty Iberia desks, hoping someone will appear and give them some information.

Shadow transport minister has criticised the government and Nats for allowing another air traffic control incident after a major outage brought UK airports to a standstill last year.

“Yet again passengers are stuck on the tarmac wondering why Britain cannot keep its own skies open," Greg Smith says.

He adds that Transport Secretary Heidi Alexander "promised after last year’s Swanwick fault that she would work with Nats to prevent this happening again. It has happened again.

“The Government and Nats must explain what has happened and how they will make sure resilience is improved.”

Earlier, Alexander said she was "aware" of the technical issue and apologised for the frustration.

Katy Austin
Transport correspondent

What’s really noticeable here at Heathrow Airport is that the skies have fallen quiet.

My understanding is Heathrow reached the point this afternoon where it couldn’t take in any more arriving flights because things hadn’t been departing - and basically the airport ran out of space.

Alfie Tobutt
BBC Your Voice

The queue for Ryanair’s ticket desk here at Dublin Airport stretches almost the entire length of the Terminal 1 departures hall.

There are so many frustrated passengers in the queue that they are blocking the doors at the entrance to the terminal.

While the air traffic control group Nats says it has implemented a fix and systems are “starting to recover”, it will be a while before the situation returns to normal.

Katy Scott
BBC Scotland news

Flights at Scottish airports have also been disrupted by the technical issue at Nats air traffic control.

Glasgow and Aberdeen say some services may experience delays and it is advising passengers to check with their airlines before travelling.

Edinburgh says Nats has implemented a fix, but knock-on disruption is likely throughout the day as operations recover.

Airports in Inverness and the Highlands and Islands say London flights are experiencing “significant delays”, but passengers should check-in at their normal time and check for updates.

Glasgow International Airport has seen 18 flights cancelled today, while 29 have been cancelled at Edinburgh Airport.

Disruption likely to persist for hours to come due to flight backlogpublished at 17:32 BST

17:32 BST

Theo Leggett
International business correspondent

Nats says the problem with its flight processing system - which provides air traffic controllers with essential information about aircraft flying through UK airspace - is being resolved.

But the disruption is likely to persist for hours to come.

Here’s the problem. Hundreds of flights have been cancelled and many more delayed across the country.

Although the technical issue affected departures, arrivals were also hit as space on the ground became increasingly restricted. So planes from overseas airports were held on the tarmac as well.

The result is that now there’s a backlog of flights, and aircraft across Europe are in the wrong place. Sorting all of this out is likely to take time.

Rozina Sini
BBC Your Voice

Image source, Chloe Davis

Chloe Davis, 18, from Cambridgeshire, is sitting on a Virgin Atlantic plane at Heathrow waiting to fly to Orlando.

She is an aspiring pilot and is not overly worried about the delays, but would like to know more about what's going on.

"We are stuck in limbo not being able to know because the pilots don't even know what's going on," she tells me.

"I went into the cockpit to speak to the pilots as I myself am an aspiring pilot," she says, adding that Flightradar is the "quietest I've seen airspace in ages".

"It's out of our control, so why worry is my motto," she adds.

Harry Whitehead
Journalist at BBC Guernsey

Guernsey and Jersey airports are facing significant delays and cancellations due to the technical issues with the UK air traffic control group Nats.

Guernsey Airport says it is working closely with airlines and provisions have been put in place to keep the airport open late "if required".

The disruption has meant that Jersey's national football club Jersey Bulls, has had to postpone its FA Cup replay match against Burgess Hill Town FC.

Image source, Reuters

London Heathrow says the issue is affecting arriving and departing flights across UK airports as it apologised to those who are impacted.

The airport is advising passengers to check with their airline for the latest flight information and only travel to the airport if their flight is confirmed.

London Gatwick has asked passengers to check with airlines for information on their flights adding that the issue is affecting them.

London Stansted has similarly asked passengers to check with their airlines before travelling. It says it will continue to monitor the situation and provide updates as more information becomes available.

London Luton, London Southend airport and London City airport have all posted similar statements.

James Kelly
BBC News

Nisha Lahiri, 46, has been sitting on board BA flight BA119 from Heathrow to Bengaluru, India, which has been stuck on the tarmac for more than two-and-a-half hours.

The flight should have departed at 2pm but has been caught up in the disruption caused by an issue with air traffic control.

"We boarded and have been waiting on the aircraft since then. I’m going for a family wedding in two days," she says.

Nisha says passengers are now being offered food, but there won't be any more until two hours before landing after the 10.5-hour flight.

She says the flight is a "priority to depart apparently," adding: "We just don’t know when as the issue with ATC isn’t resolved yet."

"The cabin crew has been helpful, they’re letting passengers use their phones to contact family if needed. Wi-Fi is also free on board."

Image source, BBC Your Voice

Air traffic control group Nats has issued a new statement saying they have issued a fix - with the flight system "starting to recover".

"We are continuing to work closely with our airline and airport customers on recovery," it adds.

Liverpool John Lennon Airport says it is aware of the technical issue with Nats’ air traffic control service, which may have some impact on departures from Liverpool.

Birmingham Airport says the issue is “impacting a significant number of departing flights across the country”. It has advised passengers to arrive in line with their airline's check-in requirements, and to contact their airline directly for the latest flight information and updates.

Manchester Airport Group says it is aware of the issues and it has advised passengers to check their flight status with their airline.

Bristol Airport says technical issues might impact departing flights, but arriving flights are not currently affected. It has told customers to check with their airline for more information.

East Midlands Airport says flights have been affected by the issue, and it has advised passengers to check with their airline providers.

Southampton Airport, Glasgow Airport and Belfast Airport have also issued similar statements on the disruption.