Hundreds of thousands of travellers have been left stranded after a major outage hit Britain’s air traffic control system, forcing the cancellation of more than 1,200 flights at the end of the bank holiday weekend.

A “network-wide” failure left controllers having to enter flight details manually, leading to colossal delays and many passengers being stuck on grounded planes for hours on end.

Air traffic service Nats said it had “identified and remedied” the fault. But holidaymakers – many of whom were returning from holidays and due to return to work on Tuesday – were braced for the chaos to continue as airlines struggle to clear the backlog.

In the worst single day’s disruption to UK flying since the Icelandic volcano in 2010, an estimated 200,000 passengers were expected to wake up up on Tuesday morning where they did not intend to be.

And while affected passengers may be able to claim for hotel or meal expenses from their airline, they will not be entitled to statutory compensation as the situation is described as an “extraordinary circumstance”.

British Airways said it had to make “significant changes to its schedule” and warned passengers not to travel to airports without first confirming that their flight was going ahead.

A spokesman for Heathrow, Britain’s biggest airport, also said flights would remain “significantly disrupted”.

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On one of the busiest days of the year for travellers, the UK air-traffic control system failed for several hours, grounding more than 1,200 flights, and delaying thousands more.

The Independent has calculated the figures using information from the aviation data service Flightradar24.

Worst hit was London Heathrow, with 312 arrivals and departures, just ahead of London Gatwick on 300.

The Heathrow figure includes a number of long-haul flights, including transatlantic departures to Chicago, Philadelphia and Toronto.

Further flight cancellations have been made at Heathrow on Tuesday, due to the number of planes and crew out of position.

Manchester had 162 flights cancelled. Its sister airport, London Stansted, saw 104 grounded. Both Edinburgh and Luton airports had 102 cancellations. Belfast International, Bristol and Birmingham airports all had more than 50 cancelled flights.

The aviation industry was already working at full stretch, with very little slack in the system particularly at Heathrow and Gatwick – respectively the busiest two-runway airport in the world and busiest single-runway airport.

Have you been affected by flight delays? Email andy.gregory@independent.co.uk

In a statement, Nats apologised for the disruption. It said: “We have identified and remedied the technical issue affecting our flight planning system this morning.

“Our engineers will be carefully monitoring the system’s performance as we return to normal operations.

“The flight planning issue affected the system’s ability to automatically process flight plans, meaning that flight plans had to be processed manually which cannot be done at the same volume, hence the requirement for traffic flow restrictions.”

Nats later updated its statement to say: “It will take some time for flights to return to normal and we will continue to work with the airports and airlines to recover the situation.”

Gemma Saleh, 43, who teaches part-time at law school and lives in Newcastle, boarded an easyJet flight with her family at 11.30am in Sardinia bound for Gatwick but ended up stuck on the plane for close to two hours.

“We were told as we started to taxi there was an issue with the air traffic computer but [the pilot] didn’t know more and we’d wait on the tarmac till we got a slot,” she said.

Londoner Julian Eccles lost half of his four-day trip to central Italy and Lake Garda. His easyJet flight from Gatwick to Ancona was cancelled and he had to book with TUI to Verona on Wednesday morning instead.

Maisie Traynor said she and her friends had been stuck on the tarmac in Glasgow for six hours with no food or drink, with little information given to them by TUI.

David Miller, a 47-year-old, had been especially keen to get home to Chester having been mugged on holiday in Barcelona – only to find himself facing 12-hour delays upon arriving at the airport.

While the captain of his British Airways flight ordered passengers to embark anyway in the hope of securing an earlier departure slot, he had warned those on board to brace for a delay of at least four hours. He praised the pilot for keeping passengers well updated, and joked: “Everyone’s jovial, the air con’s on.”

Joanne Colley said her group was stranded in Turkey, with no alternative BA flights scheduled back for the rest of the week. She said she was now looking at indirect flights, or possibly “even driving home”.

Ashleigh Blaney, a 34-year-old finance assistant from Glasgow, had been in Amsterdam watching the Dutch Grand Prix with her brother, both of whom found themselves stranded in Schiphol airport.

Ms Blaney told The Independent that they had been queueing for over an hour in border control in an attempt to exit the airport, and that no one could tell them where they could pick up their checked-in luggage, describing the situation as an “absolute nightmare”.

While they had managed to rebook their flight tomorrow, it was arriving in Edinburgh instead – and there were no hotels available on the easyJet app, Ms Blaney said. Her brother, who had been due to fly to Gran Canaria at 6am tomorrow, will no longer be able to make his trip.

Erica Francker said that she and a group of students were stuck in Marseille with a delay of several hours. “We’ll get vouchers, which are £3 to £4.50 for easyJet, for food after three hours delay, but we’re also told to not leave the gate for too long,” she said.

Irene Franklin, 60, had her Delta flight from Heathrow to Austin, Texas – along with her daughter, son-in-law and two friends – cancelled at the last minute. She said: “It was [saying delayed by] two hours, now it’s cancelled. It’s now not until tomorrow morning at 10. It’s frustrating but what are you going to do?”

Gordon Wheeler said his daughter, her partner and two young children were stuck in Alicante, having already had their original easyJet flight cancelled last Thursday. They had to pay for emergency accommodation and food for four days, and are now facing further delays.

Broadcaster Gabby Logan was among those stuck on a flight after being informed that UK airspace “is shut”. But she later said the flight was taking off.

Home secretary Suella Braverman sympathised with anyone affected.

She told broadcasters: “I am very cognisant that this will disrupt people’s travel plans – those who are waiting to arrive in the UK, those waiting to depart, and I do sympathise with any disruption they may be experiencing.”

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