However, at the moment, the list of cancelled flights only goes up to September 20. "We have messed up in the planning of pilot holidays and we're working hard to fix that", marketing officer Kenny Jacobs was quoted as saying by BBC.
The mishap was caused by Ryanair changing its annual calendar.
But what are your rights if your flight is cancelled and you've been left out-of-pocket?
Under EU rules, if your flight departed from an EU airport or is an EU airline landing at an EU airport, and your flight was cancelled within 14 days of departure, you may also be eligible to claim additional compensation of between 125 and 600 euros.
Hannah Maundrell, editor in chief of price comparison site Money.co.uk, says: "It's so disappointing for Ryanair passengers whose flights have been cancelled especially at such late notice".
At the conference, O'Leary said it had taken time to release the full list of cancelled services as it had given priority to communicating with passengers due to travel in the short term.
BUDGET airline Ryanair is struggling to control a wave of anger from an increasing number of furious customers who are unsure if their flights will be cancelled over the next six-weeks.
If you are affected you should have received an email, otherwise your flight should remain unchanged.
Ryanair has the form on its website you need to fill-in.
If I can't get to my destination until later, what about the other things I've booked?
Many customers are furious that the cancellations will also affect existing paid hotel and accommodation bookings.
If Ryanair has informed you of the cancellation with more than two weeks' notice, you will not be entitled to compensation.
Ryanair will offer refunds or alternative flights to customers affected by the cancellations. Be sure to document what you spend, though and keep receipts.
The airline has outlined the affected flights, but only up until this Wednesday.
He told the Times: 'We expect all airlines to fulfil their obligations to their customers and do everything possible to notify them well in advance of any disruption to their journey.
He explained": "We have an unusual situation with Ryanair, moving from a 12-month leave from April to March called the fiscal year.