Ryanair has announced that it would cancel 40-50 flights daily for the next six weeks (to the end of October) to improve its system-wide punctuality which has fallen below 80% in the first two weeks of September through a combination of ATC capacity delays and strikes, weather disruptions and the impact of increased holiday allocations to pilots and cabin crew.

Ryanair has operated at record schedule and traffic levels during the peak summer months of July (12.6m guests) and August (12.7m guests) but has a backlog of crew leave which must be allocated before 31 December 2017 in order to switch to a calendar leave year (as required by the IAA) from 2 January 2018 onwards.

"These tighter crewing numbers and the impact of ATC capacity restrictions in the UK, Germany and Spain, as well as French ATC strikes and adverse weather (thunderstorms) have given rise to significant delays in recent weeks," Ryanair said. " Ryanair's on-time performance has declined from 90% to under 80% over the past two weeks, a figure that is unacceptable to Ryanair and its customers."

The airline said that it was unacceptable that punctuality had fallen below 80% in the first half of the month, and said a backlog of staff leave had to clear by the end of year.

The airline said that less than 2% of flights would be cancelled.

Ryanair apologised for the inconvenience caused to customers by these cancellations.  Customers will be contacted directly about this number of cancellations and offered alternative flights or full refunds.