An aircraft is provided. The aircraft includes a pressurized volume and an air conditioning system. The air conditioning system operates in a first mode when the aircraft is performing high altitude operations and a second mode when the aircraft is performing low altitude operations. The first mode includes when a first medium, a second medium, and a third medium are mixed by the air conditioning system to produce a chamber ready medium. The second mode comprises when only the first medium and the second medium are mixed by the air conditioning system to produce the chamber ready medium. The air conditioning system provides the chamber ready medium to the pressurized volume.