The company anxious millions of customers by announcing on Friday that it expects to cancel 40 to 50 flights a day for the coming six weeks.
Michael O'Leary has confirmed all customers affected by the flight cancellations up until the end of October will receive an email by this evening and the list will also be published on the Ryanair website.
A Longford Westmeath TD says Ryanair shouldn't be selling tickets for flights that could be cancelled.
Ryanair said it would contact customers affected by the cancellations immediately with an offer of alternative flights or full refunds.
The cancellations could affect up to 400,000 passengers amid speculation that pilots are deserting the airline to work elsewhere.
Ryanair said it was not short of pilots after Norwegian Air said it had hired more than 140 of the Irish airline's pilots this year.
Initially, Ryanair was only making available lists of cancelled flights up to this Wednesday, 20 September.
As a result of this change, Ryanair marketing officer Kenny Jacobs says the airline had to allocate a load of annual leave to pilots in September and October.More news: The GOP's Last-Ditch Effort To Repeal ObamaCare Is Surprisingly Good
While the scrapped flights account for only about 2% of normal daily operations, the cause was avoidable and stems from the company's aggressive management style.
If you're now stranded overseas or about to travel, Ryanair should offer you an alternative flight.
"You weren't able to offer me another flight in time for me to get back for work", she wrote.
He was at pains to add that the airline will not contest this compensation, saying: "When we make a mess in Ryanair, we come out with our hands up".
This will inform them what flights they can transfer to which will be "hopefully on the same or, at worse, the next day". Ryanair also said air traffic control strikes and weather disruptions were affecting its performance.
The fiasco undermines O'Leary's efforts to improve Ryanair's image and woo more lucrative customers.
The airline said it was cancelling flights at airports where it ran the busiest schedules, so it would be easier to place passengers on alternative flights.
But it now has a backlog of holidays for pilots and crew members which must be taken before the end of the year in order to switch to a calendar leave year - as required by regulators - from January 2018 onwards. Flights are operating as usual for customers who haven't received emails from the carrier.