The European budget airline said it will fly 25 fewer aircraft from November 2017 and 10 fewer from April 2018 in order to eliminate the risk of further flight cancellations. Ryanair says that about 18,000 flights will be canceled, many of which have zero booking.

Affected customers were contacted and offered a refund or flight change, the airline said, but maintains that 99% of its customers will remain unaffected.

Ryanair said it plans to roll out a series of low-cost flights for the winter as they are “confident that there will be no further roster related cancellations.”

The move comes after an ongoing battle between pilots and other cabin staff over working conditions. The budget airline canceled more than 2,000 flights earlier in September.

Ryanair says this will be the last round of cancellations.