Ryanair has announced that it will cancel 40-50 flights every day for the next six weeks.
The budget airline cancelled 82 flights on Sunday after admitting it had "messed up" the planning of its pilots' holidays.
A page on the Ryanair website details flights cancelled up until 20 September. It says 56 flights are cancelled on Monday, 55 on Tuesday, and 53 on Wednesday. The cancellations could affect up to 285,000 passengers all over Europe, who will be offered alternative flights or refunds.
Most of the cancellations are due to a backlog of staff leave which has seen large numbers of the airline's staff book holidays towards the end of the year.
The airline is changing its holiday year, which currently runs from April to March, to run from January to December instead.
Rynanair said the shift meant it had to allocate annual leave to pilots in September and October.
Marketing officer Kenny Jacobs said affected customers with bookings up to 20 September had been informed.
"We have messed up in the planning of pilot holidays and we're working hard to fix that. We advise customers to check the email address used to make their booking," he added.
Ryanair stated that less than 2 per cent of its flights would be cancelled and the move would help it hit its annual punctuality target of 90 per cent.