EasyJet says it will cancel more than 200 flights over the next 10 days, putting half-term breaks at risk for thousands of travellers.
The airline said about 24 flights from Gatwick would be affected each day between now and 6 June.
A spokeswoman for the company said: “We are very sorry for the late notice of some of these cancellations and inconvenience caused for customers booked on these flights, however we believe this is necessary to provide reliable services over this busy period.
“Customers are being informed from today (Friday) and provided with the option to rebook their flight or receive a refund and can apply for compensation in line with regulations.
“Over the next week we will be operating around 1,700 flights per day, with around a quarter of these operating to and from Gatwick.”
Meanwhile, passengers are facing lengthy queues at airports including Gatwick, Manchester, Stansted and Bristol.
Also, holiday firm TUI says some of its flights have been cancelled or delayed.
A spokesperson said: “The half-term holidays are always an incredibly busy period with many customers looking to get away. Unfortunately, due to various operational and supply chain issues a small number of flights have been delayed or cancelled.
“We’d like to reassure customers that we are doing everything we can to minimise delays and will be in direct communication should their holiday be impacted. We’d like to thank customers for their patience and understanding during this time.”
British Airways has said it is set to operate its schedule as planned and is not experiencing any significant issues.
In other travel disruption, Liverpool FC supporters faced long delays at the Port of Dover on Friday as they waited to cross the Channel to Paris for Saturday’s Champions League final against Real Madrid.
There is also high demand for sailings from families embarking on trips to the continent for half-term.
The port said passengers should pack adequate supplies as it is expecting “a very busy week ahead”.