It has furnished a list of affected flights up until Wednesday, but so far Shannon flights aren't affected.
"We will not pay for flights on other airlines, no. We have only taken this decision to cancel this small proportion of our 2,500 daily flights so that we can provide extra standby cover and protect the punctuality of the 98% of flights that will be unaffected by these cancellations", he added.
If not, they would be moved to flights the day before or the day after and the airline would meet its obligations over compensation. If you have a trip coming up, and booked your flights with the budget airline, then that's unlikely to be the sort of pre-holiday news you need.
Carole Schofield tweeted: "How the hell do you know if you can get back". Ryanair said that it will release a full list of canceled flights (through the end of October) by Tuesday. Will my flight on Thursday be cancelled or not?
"Yes it was short notice and unexpected but we were doing our best at short notice to contact passengers who were affected".
But he says they have only been given details of the cancellations up to Wednesday of this week so are "in the dark" after that.
The cancellations, which begin immediately, are designed "to improve its system-wide punctuality which has fallen below 80 percent in the first two weeks of September", Ryanair said in a statement, describing the number of delayed flights as "unacceptable" to customers.
The holiday issue arose from a change from holiday allowance in the company running for a fiscal year to a calendar year. Compensation is also only payable if the cancellation is the airline's fault.
How much you get depends on when you were told about the cancellation, the distance of your flight, and the delay to your journey based on the arrival time of the rescheduled flight you're offered. Keep receipts of everything you spend.
Move quickly and try to reschedule your flight as soon as you find out yours is cancelled.
He explained": "We have an unusual situation with Ryanair, moving from a 12-month leave from April to March called the fiscal year.
You can also potentially claim on your travel insurance for lost holiday bookings or extra expenses if your flights are cancelled by Ryanair.
The low-priced carrier said it "messed up" staff holiday applications, meaning it would be forced to cancel two per cent of its flights each day in order to give pilots and other employees sufficient time off in the coming weeks.