Air France-KLM regional carrier CityJet's long-term chief executive, Geoffrey O'Byrne White, has resigned from his post and will leave the company this month.
O'Byrne White, who has led the airline for a decade, has not given a reason for his decision.
During his tenure, he oversaw the acquisition of Belgian operator VLM which was subsequently integrated with CityJet's operations.
Chairman Pat Byrne is to take on the chief executive's role temporarily. Chief financial officer Michael Collins will assume the post of deputy chief.
Irish-based CityJet has a fleet of some 40 aircraft comprising BAE Systems Avro RJs and Fokker 50 turboprops.