An aircraft air conditioning system comprising an air conditioning unit adapted and configured to be supplied with compressed process air and to generate cold fresh air, a mixer adapted and configured to mix the cold fresh air from the air conditioning unit with recirculation air recirculated from an aircraft region to be air conditioned, an air outlet adapted and configured to direct mixed air from the mixer into the aircraft region, a first sensor adapted and configured to detect an actual temperature in the aircraft region, a second sensor adapted and configured to detect a temperature of the mixed air directed into the aircraft region, and a control unit adapted and configured to control an operation of the air conditioning unit in dependence on a difference between the temperature of the mixed air directed into the aircraft region and the actual temperature in the aircraft region.