The walkout is due to begin at midnight on Thursday until the end of Friday, with another two days of action planned from 2-4 September.
The British Airline Pilots Association (BALPA), which represents the striking pilots, said on Monday that the Irish budget carrier had lost the chance to resolve its dispute with the pilots by wasting time on “unnecessary court action”.
Brian Strutton, BALPA’s general secretary, accused the airline of “bullying tactics” its attempt to legally block the strike while also criticising the firm for continuing to sell tickets for flights due to take place during the walkout.
Another 48-hour strike by 180 of the company's pilots was blocked by the High Court in Dublin on Wednesday.
The airline isn’t the only carrier facing disruption over the busy summer period, with British Airways, owned by International Consolidated Airlines Group (LON:IAG), also facing the possibility of pilot strikes after an attempt to block the industrial action was thrown out by the UK High Court.
--Updates with Irish strike ruling---