Ryanair have announced a decision to cancel up to 50 flights a day over the course of six weeks to catch up with staff holiday entitlement.
Due to an overworked workforce across the peak summer period, the airline have built up an excess of holiday debt with pilots and cabin crew.
Many passengers have spoken out about the decision, calling the cancellations as an "absolute disgrace" and "shocking".
The airline's head of communications, Robin Kiely, said: "We apologise sincerely to the small number of customers affected by these cancellations, and will be doing our utmost to arrange alternative flights and/or full refunds for them."
Ryanair have cancelled nearly two percent of their scheduled flights due to the error in holiday management.
Kiely added: "We have operated a record schedule and traffic numbers during the peak summer months of July and August but must now allocate annual leave to pilots and cabin crew in September and October while still running the bulk of our summer schedule."