Thousands of airline passengers have been impacted by cancelled, delayed or diverted flights due to a lack of air traffic control staff (ATC) at Gatwick airport.

The airport confirmed a short notice staff absence in its ATC tower, managed by National Air Traffic Services (Nats), which meant 42 flights were cancelled or diverted while dozens more were heavily delayed on Thursday.

More than 6,000 passengers are likely to have been affected by cancellations.

It comes just over two weeks after a Nats technical glitch caused widespread disruption at airports across the UK, leaving thousands of holidaymakers stranded overseas for several days.

Ryanair boss Michael O’Leary has called on Nats chief executive to resign, while easyJet said it is “very disappointed” its customers have been affected again.

Mr O’Leary said: “It is unacceptable that more flights and hundreds of passengers are suffering delays to/from Gatwick Airport due to Nats CEO Martin Rolfe’s blatant failure to adequately staff UK ATC.

“Airlines are paying millions of pounds to Nats each and every year and should not have to see their passengers suffer avoidable delays due to UK ATC staff shortages.”

An easyJet spokesperson said: “We are very disappointed that customers are once again impacted by this and while this is outside of our control, we are sorry for the inconvenience caused to our customers.

“We are doing all possible to minimise the impact of the disruption, notifying those on cancelled flights of options to rebook or receive a refund and provided hotel accommodation and meals where required.”

Julia Lo Bue-Said, chief executive of Advantage Travel Partnership – a network of independent travel agents, said: “The situation at Gatwick is unacceptable. This kind of disruption causes havoc for travellers and has huge financial implications for airlines, travel agents and the entire ecosystem.

“There needs to be an urgent inquiry into why there appears to be staff shortages in this crucial area, and measures implemented to stop these incidents occurring again.”

PA news agency analysis of flight tracking data shows that first departure cancelled due to air traffic control restrictions was an easyJet flight to Berlin, due to take off at 5pm.

Fourteen departures and 12 arrivals were cancelled at Gatwick on Thursday from that time.

The first diverted arrival was a British Airways flight from Faro, Portugal.

It was due to touch down at 3.35pm, but landed at Cardiff Airport instead.

A total of 16 arrivals were diverted to a range of airports: including Bournemouth, Cardiff, Heathrow, Luton and Stansted.

Gatwick airport later said an additional air traffic controller was put in place and restrictions were reducing, allowing more aircraft to arrive and depart.

Laura Neary, 29, was due to catch a Ryanair flight to Dublin at 5:30pm, but it diverted to London Stansted, which she had to travel to by coach.

Ms Neary, who was travelling on her own, said some of the passengers received text messages saying they would need to take a coach to reach Stansted, in Essex, while others were told they could still board the flight from Gatwick.

The sales worker, who is from the Irish capital, told the PA news agency: “I don’t even know if I can get back to Dublin tonight.”

It is the third time in just over a fortnight that flights to and from the Sussex airport have been disrupted as a result of problems at Nats.

On August 28, Bank Holiday Monday, the Nats control system for the entire UK was hit by a technical glitch, causing widespread disruption.

More than a quarter of flights to and from UK airports were cancelled that day, affecting around 250,000 people.

Cancellations continued for two more days as planes and crews were out of position.

A week later, the airport was subjected to a restriction in the number of planes that could take off and land because of “short notice sickness”.

Nats said it is “working in line” with a staffing plan agreed with Gatwick bosses when it took over the provision of ATC services at the airport in October 2022, which includes training further controllers.

It said it can take up to a year for qualified controllers to complete the “specific training” required to work at an airport control tower.

Nats said: “Air traffic control restrictions have been put in place this afternoon due to a short notice staff absence affecting our air traffic control team at Gatwick Airport.

“We are working closely with the airport to ensure we can handle flights with as little disruption as possible and we apologise very sincerely to people who have been inconvenienced [as a result of unavoidable diversions].

“We are working closely with Gatwick Airport Ltd to build resilience in the airport’s control tower to ensure disruption is kept to a minimum.

“New air traffic controllers have been recruited since last summer, increasing our presence by 17%, and others are due to start after completing their training, in line with the agreed plan when Nats took over the contract last October.

“London Gatwick’s senior management understands that we are working hard to keep the operation moving. Airlines operating at London Gatwick were aware of the situation when Nats was appointed but that does not dilute the apology we offer sincerely to them and their passengers who have been inconvenienced by recent disruption.”

Gatwick airport apologised to affected passengers, urging them to contact their airlines for information.

The spokesperson added: “Nats are a world-class provider of air traffic services and London Gatwick’s senior management recognises how hard the airport’s air traffic controllers are working to keep the operation moving.

“We are working closely with Nats to build resilience in the airport’s control tower to ensure disruption is kept to a minimum.”