A novel displacement ventilation system, relying on air supply through the ceiling, has been developed, installed and investigated in the Do 728 test bed of the German Aerospace Center. The system uses a new ceiling air outlet concept, which allows for simultaneous supply of air and further functions like e.g. lighting or acoustic damping in future applications. Six different ventilation scenarios, among them mixing ventilation, cabin displacement ventilation, ceiling based displacement as well as combined ceiling and floor based dis-placement ventilation were studied and compared. Passenger thermal dummies were used to simulate ex-perimentally the impact of the passengers under real conditions. Flow velocities, fluid temperatures and sur-face temperatures were measured in the cabin, including the vicinity of the passenger dummies. This data was used to determine integral quantities like the temperature difference between cabin air and incoming air, the heat removal efficiency, the mean temperature stratification and the mean velocity levels in order to analyze and score the ventilation scenarios. A combined operation of the floor and ceiling based displacement ventilation system can ensure at once high heat removal efficiencies as well as predictably comfortable flow conditions.