A walkout is scheduled from 30 October to 2 November, affecting services to New York, Orlando and Barbados.
The dispute means that instead of flying direct with UK-based crew, passengers will fly from Manchester to Dublin and transfer to long-haul services there.
The strike follows a vote by 130 members of Manchester cabin crew, who are represented by the Unite union and who are employed on a different contract to their Dublin-based colleagues.
They have rejected a package offering a 9% pay rise this year and 3% next year, voting 90% in favour of action.
