Aer Lingus says the threat of a work stoppage next Friday has forced it to change some of its flights.
SIPTU staff at the airline are planning to walk off the job for four hours in a long-running row over pensions.
It is hoped the action will be called off, but Aer Lingus says it has hired more aircraft, rescheduled flights, and re-booked customers on other carriers just in case.
Customers booked to travel during these times are advised to check the status of their flight on www.aerlingus.com