Ryanair is offering pilots bonuses of up to €12,000, if they agree to give up their annual leave entitlements.
It's seen as an attempt to plug gaps in its flight schedule, which will see up to 50 flights cancelled every day day for several weeks.
Ryanair has published the full list of flight cancellations for the next five weeks.
The carrier says these cancellations have been allocated to its bigger base airports, and routes with multiple daily frequencies.
Six Ryanair flights in and out of Dublin are among the 55 affected today.
The airline says the cancellations are due to a backlog in its annual leave for staff.
The company is moving its holiday year from the current system of April to March to a calendar year of January to December from January 2018.
It says the backlog must be cleared before December 31st this year.
Affected customers will be contacted directly and offered alternative flights or full refunds.
