Twelve flights into and out of Dublin are among the 57 cancelled by Ryanair across Europe today.
The airline announced on Friday that it was cancelling dozens of flights per day over the next six weeks amid a "backlog of crew leave".
Tens of thousands of passengers are expected to be directly affected.
Passengers are being offered a refund or seats on a later flight.
Ryanair has published lists of flights cancelled until Wednesday, but there are calls for the company to reveal details of all flights due to be impacted.
Services between Dublin and Brussels, Amsterdam, Manchester, London Gatwick, Bristol & Barcelona are among those affected today.
Paul Bolger from consumer Website myrefund.ie has this advice for passengers: