The CEO of Malaysia Airlines is taking over Ryanair's flight operations.
Peter Bellew is joining Michael O'Leary's team as Chief Operations Officer.
He previously worked with the airline.
Malaysia Airlines has suffered a number of serious incidents in recent years, most notably the disappearance of MH370 and its passengers.
Michael O’Leary said: "Having worked previously in a senior role in our operations team, Peter has an unrivalled knowledge of our business model and how we maintain controlled growth, with industry leading punctuality, for the benefit of our customers and our people.
"Peter will lead a significant transformation in the way we reward and interact with our pilots, improve their working environment and career development over the coming years as we grow the fleet to some 600 aircraft and expand our traffic."
Mr Bellew said: "I am excited to return home to Ryanair and take up the challenge to grow the operation sustainably.
"I look forward to working with all the team and all the crews I know so well to further develop our growth to 600 aircraft over the next six years."