Monarch Airlines chief executive Peter Brown is to step down with immediate effect after eight years in the role.
Monarch chairman Iain Rawlinson will take on senior executive responsibility for the group on a temporary basis while the group seeks a replacement.
He will be supported by the management committee which includes Monarch Airlines managing director Tim Jeans, Cosmos mainstream products managing director Stuart Jackson and Cosmos Tourama managing director Alan MacLean.
Rawlinson said: “Peter has been instrumental in guiding the group through a formative period in its long history. Monarch today has balanced exposure to both chartered and scheduled airline operations, a strong travel brand and a supportive family shareholder base.
“The group is emerging from the very challenging recent period with a sound business model which offers scope for growth in the years ahead.
“We would like to thank Peter for his contribution to both Monarch, and to the airline industry. We wish him the best for the future.”
Brown said he was looking forward to a “new challenge”.