Irish Aviation Authority (IAA) executive Diarmuid Ó Conghaile will resign from the role at the end of October in a surprise move.
He was chief executive designate of what will be a reconstituted IAA, once new legislation is passed.
Mr Ó Conghaile was general manager of strategy, planning and economic regulation at the DAA, which operates Dublin and Cork airports, before leaving to join Ryanair in 2016. At Ryanair, he was initially director of public affairs and went on to head its Malta Air subsidiary.
He was appointed chief executive designate of the IAA in early 2021.
New legislation will see the Commission for Aviation Regulation disbanded and it separates the commercial and regulatory functions of the Irish Aviation Authority.
Under the planned new legislation, air navigation operations, including air traffic control, will become a standalone entity called AirNav Ireland.
The IAA’s current chief executive is Peter Kearney. He will be chief executive of AirNav when it is formally established.
A reconstituted IAA will be the overall sectoral regulator with responsibility for safety and security, as well as regulating passenger charges at Dublin Airport, consumer protection and licensing and supervision of the travel trade.
However, implementation of the legislation has been delayed for more than a year.
Last month, the leader of the Seanad, Regina Doherty, told the Irish Independent that the house was being asked to pass crucial legislation designed to implement the structural change without reassurances regarding significant concerns senators have about the proposed laws.
Ms Doherty claimed that the IAA “has resisted” taking on additional responsibility. She and other senators have also expressed concerns that the Department of Transport availed of advice from the IAA in drafting elements of the new legislation, rather than relying on external advice.
The Irish Airline Pilots’ Association has called for a number of amendments to be made to the legislation, including mandatory peer support programmes at air operators that would have to be reviewed at least once every three years.
IAA chairman Rose Hynes thanked Mr Ó Conghaile for his contribution to the implementation of the separation policy. The IAA board will start a process to find a successor to Mr Ó Conghaile as soon as possible.
The aviation authority recently formally opened its new 87-metre-high control tower at Dublin Airport, which was built at a cost of €50m.