Frederic Gagey would remain as head of Air France, the source said.

Sixty-three year old Janaillac, CEO of multi-modal transport company Transdev since 2012, first occupied a senior position in the airline industry when he was associate director general at now defunct airline AOM in the late 1990s. He is a graduate of France's elite administration school ENA and the HEC business school.

Air France-KLM declined to comment. Transdev was not immediately available for comment.

De Juniac announced his surprise departure to lead the International Air Transport Association (IATA) earlier this month, saying he had achieved his goals of ending losses and reducing debt, despite having three years left of his mandate.

People close to him said de Juniac had been worn down by conflict with the company's powerful unions. Others have said de Juniac, who served at the treasury under former conservative President Nicolas Sarkozy, enjoyed only lukewarm support from the Socialist government over job cuts, an issue that could become a headache for his successor.

Air France-KLM's nomination committee on Friday decided to back Janaillac, the source said, paving the way for his nomination by the board on Tuesday.

(Reporting by Cyril Altmeyer; Writing by Ingrid Melander; Editing by Richard Balmforth)