As well as air traffic control strikes and weather disruption, the airline said the decision was taken to meet a requirement for holiday time for its crews following the introduction of a new roster structure as required by regulators.
A Ryanair spokesperson said, "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)".
Some claimed they were left "stranded" as the replacement flights they were offered were for several days later.
The Commission for Aviation Regulation has released a statement containing advice for people who have been affected by the cancellations.
"Then, when attempting to obtain a refund using the "change flight/refund" tabs, the initial page says flight is indeed cancelled but further into the refund process the system says it can not process a refund as the flight is not cancelled", she told the Independent.
Ryanair's Kenny Jacobs said: 'We will cancel 40 to 50 flights daily for the next six weeks, (less than 2% of our schedule) with a slightly higher number this weekend as we begin to implement these cancellations.
Mr Currie said it would have cost him and his grandmother nearly €1,000 in total to book alternative flights with another airline and so they managed to negotiate a deal with their hotel to remain for the weekend.More news: Trump takes advantage of the London attack to promote his travel ban
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Ryanair is cancelling flights to meet punctuality targets.
Ryanair, an airline popular for its affordable flights, carried more than 100 million passengers past year.
Travel agents are demanding the low-fares carrier publish a full list, but Michael O'Leary's behemoth is instead content to email passengers with a few days' notice.
Flights will be operating as scheduled unless passengers have received a cancellation email.
And if you're one of the ones who's affected, the reason behind all the cancellations will probably piss you off even more: it's to clear a backlog of staff leave, and to regulate punctuality of the airline's flights.
For today, Saturday, flights between Dublin and London, Paris, Barcelona, Edinburgh, Madrid and Amsterdam are among the large number cancelled across Europe.
"Alternatively you must be offered a full refund".