A critical aspect of operating an airline is to continuously maintain adequate staffing levels of qualified crewmembers. The airline must be able to plan several years in advance, taking into account factors such as forecasted flight volume, fleet growth or downsizing, and training and annual leaves of crewmembers. This short paper describes the architecture and the functionality of the Altitude Manpower Planning system developed by AD OPT Technologies in collaboration with researchers at the GERAD Operations Research Centre. It has been prepared for publication in OR/MS Today.