easyJet has cancelled 1,700 flights in July, August and September at London, Gatwick which affects 180,000 flights.
The budget airline said that 95% of passengers affected have been rebooked on other easyJet flight, but 9,000 are still facing travel disruption as they have not been given a replacement.
easyJet are claiming that there is “unprecedented” air traffic control delays and the airlines planes are all fully crewed.
However, under European air rules, passengers who have had their flights cancelled are allowed to fly on any other airline, if they have seats available on the day their flights were booked and easyJet would have to pay the bill.
If passengers have been left with less than two weeks notice then they are entitled to £220 in compensation and if they are flying more than 1,500km then it is £350, unless the airline they are travelling with can rebook them on another flight which has to be close to the original time of departure.
Julia Lo Bue-Said, chief executive, Advantage Travel Partnership, told The Independent: “This is really going to be devastating for many families and people who are looking forward to their plans and ready to depart.
“Trying to source new flights at the last minute won’t be helpful for anybody.”
A spokesperson for easyJet told The Independent: “We are currently operating up to around 1,800 flights and carrying around 250,000 customers per day and like all airlines, we review our flights on an ongoing basis.
“As Eurocontrol has stated, the whole industry is seeing challenging conditions this summer with more constrained air space due to the war in Ukraine resulting in unprecedented ATC [air-traffic control] delays, as well as further potential ATC strike action.
“We have therefore made some pre-emptive adjustments to our programme consolidating a small number of flights at Gatwick, where we have multiple daily frequencies, in order to help mitigate these external challenges on the day of travel for our customers.
“Customers whose flights are affected are being informed, with 95 per cent of customers being rebooked onto an alternative flight and all customers provided with the option to rebook or receive a refund.
“We are sorry for any inconvenience that this may have caused.”
The aviation veteran Paul Charles, chief executive of the travel consultancy The PC Agency, said: “I’ve been warning for some time that our UK airport infrastructure, along with continuing people shortages at airlines and ground handlers, cannot cope with the massive summer demand.
“Just when you thought you had secured a flight to your summer holiday paradise, it gets changed and causes more inconvenience and stress.
“Airlines have to get better at planning and delivering, not letting down customers at short notice. EasyJet aren’t the first and won’t be the last to take such action this summer.”