Aer Lingus chief executive Christoph Mueller is to leave the company in May of next year.
He has been CEO and an executive director at the company since 2009, and says now is the right time to hand over the reins.
"I have thoroughly enjoyed my five years as chief executive of Aer Lingus since 2009," he said in a statement.
"There have been very significant achievements delivered by the board and management team in that period of time.
"The last five years has involved very hard work for the entire team at Aer Lingus and it is rewarding to see that the company is well positioned both strategically and financially."
The Aer Lingus chairman Colm Barrington has thanked him in a statement this morning, saying the company has become a strong consistently profitable airline under Mr Mueller's leadership.
"Under Christoph’s strategic leadership, Aer Lingus has been transformed into a strong, consistently profitable airline with a clear strategic direction, a resilient business model as a value carrier and an improved cost base," he said.
"Christoph has placed Aer Lingus in a position where we can look to the future with confidence and can continue to develop and grow the airline for the benefit of our customers, our employees and our shareholders.
"I am also particularly grateful to Christoph that in mutually agreeing a departure date that is some time away, in May 2015, Aer Lingus has sufficient time to both conduct a thorough process to select and appoint a new chief executive and to ensure that a comprehensive and seamless transition process is completed."
The airline has been dogged by strike threats relating to a pensions dispute in recent months.