The airline said it will email customers affected with offers of alternative flights or full refunds, and details of their EU261 compensation entitlement.
It is estimated that around 350,000 passengers could be directly affected by cancellations, though many may not realise flights are cancelled until shortly before their departure date.
The airline has "apologised unreservedly" to affected customers, who will be emailed with offers of alternative routings or refunds, it says.
While the airline says only two per cent of flights will be cancelled, the move has the potential to affect hundreds of thousands of passengers.
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.
"We have messed up in the planning of pilot holidays and we're working hard to fix that".
The Dublin-based carrier is shelving up to 50 flights daily over the next six weeks due to the over-allocation of pilots' holidays during a relatively busy period.
Ryanair's CEO Michael O'Leary has addressed the issues regarding the flight cancellations affecting the airline.
Ryanair Slumps as Scrapped Flights Risk Reviving Bad-Boy Image
Carole Schofield tweeted: "How the hell do you know if you can get back".
"We have to check if all this is respected by Ryanair".
Until this is released, it should let passengers cancel their flights without penalty. And the reason for the cuts may annoy those affected, as the airline has revealed that it is in a bid to improve punctuality of flights, and also clear a backlog of staff leave by the end of the year. "We don't have enough stand-by coverage to cover the inevitable disruptions that happen - air traffic control disruption and weather", he said.
The page will be continually updated throughout the six weeks of mayhem, so it's worth keeping an eye on if you've a later Ryanair flight booked.
Ryanair is mandated by the Irish Aviation Authority to bring staff time-off in line with the calendar year from January 1, requiring it to distribute the backlog before the end of 2017.
If Ryanair has informed you of the cancellation with more than two weeks' notice, you will not be entitled to compensation.
As the requests for information kept coming, the airline later tweeted: "Hi, between today and tomorrow all flights cancellations up and until OCT31 will be communicated".
This web form can also be used to reclaim expenses caused by the cancellation, such as needing to make extra hotel bookings or pay for additional meals.More news: Rob and Blac Chyna Settle Custody Battle
More news: USC tops Texas in 2OT thriller
More news: Citing London terrorist attack, Trump calls for expansion of his travel ban