In the year to March 2019 Ryanair has revealed it will carry 4 million fewer customers than planned, with the number falling from 142 million to 138 million.
The cost of free ticket vouchers issued to passengers affected in the new round of cancellations will be about 25 million euros ($29 million), bringing the tally since the start of the crisis to nearly 50 million euros.
Ryanair is facing "enforcement action" for failing to give customers accurate information about their rights following hundreds of flight cancellations.
It made the announcement while confirming plans to suspend 34 of its routes over the November-March winter season to prevent any further mass cancellations.
The airline's already axed more than 2,000 flights over six weeks after miscalculating crew leave.
Ryanair said by reducing its flying schedule in this manner it would cut the risk of further flight cancellations, with spare capacity created across its 86 bases this winter.
It said that affected customers have received an email today giving them between five weeks to five months notice of these schedule changes, offering them alternative flights or full refunds of their airfare.
"We have less than 400,000 customers booked on these flights, (which affects less than 1 flight per day across our 200 airports over the 5 month winter period), and many of these flights have zero bookings at this time".
According to Ryanair, fewer than 100 of over 2,000 captains left Ryanair this year, with fewer than 160 co-pilots leaving, many due to retirement or for longer-haul routes. Our full year traffic of 131 million will now moderate to 129 million, which is 7.5% up on last year.
To help allow it to "eliminate all management distractions" the airline has also ended its interest in purchasing Italy's Alitalia.
The letter concludes: "Rest assured there will be no repeat of last week's roster related flight cancellations".
Ryanair customers can find out which flights are affected and about compensation or re-scheduling arrangements on the company's website.
The airline's shareholders have reportedly been warned to expect "lower yields" as a result of "slower growth" over the next two months.
Analysts welcomed Ryanair's decision not to pursue its interest in Alitalia.