Aer Lingus chief executive Stephen Kavanagh will step down from the role at the end of the year and be replaced by British Airways executive Sean Doyle.
Kavanagh, who will remain on Aer Lingus's board as a non-executive director, has led the Irish carrier since February 2015. He has overseen its continued growth since its acquisition by BA parent IAG that same year.
"After a 30-year career in Aer Lingus, with the last four years as chief executive, I've taken the decision to step down to pursue other interests," states Kavanagh.
"By any objective measure Aer Lingus has been successful in recent years and continues to have significant opportunity to build upon the strong fundamentals of our value model."
Aer Lingus posted an operating profit of $306 million in 2017, a fifth consecutive year of improved profits.
Doyle, who is originally from Cork in Ireland, is currently BA's director of network, fleet and alliances. He will take up his new role in January.
IAG chief executive Willie Walsh notes that Doyle has "successfully held a variety of roles within British Airways, acquiring significant expertise and experience, which makes him ideally suited to lead Aer Lingus".
Walsh adds: "I am pleased that Aer Lingus chief operating officer Mike Rutter has extended his contract and will work with Sean to ensure that the airline continues to deliver its strong performance."