Patent ID: 7797962

Claim:
A method of operating an aircraft system for the purpose of fresh air supply, air-conditioning and pressurization of an aircraft cabin, having a first compressed air source formed by a first compressor charged with ambient air, ram air and/or precompressed air and driven by means of at least one motor and/or of at least one turbine and whose outlet is in direct or indirect communication with the aircraft cabin, said aircraft system having at least one second compressed air source whose outlet can be connected directly or indirectly to the aircraft cabin, comprising: operating in a first operating mode where only the first compressed air source is in communication with the aircraft cabin, and operating in a second operating mode where both the first and the second compressed air sources are in communication with the aircraft cabin, wherein a selection of an operating mode depends on a pressure of the ambient air such that the first operating mode is selected at a high pressure of the ambient air and the second operating mode is selected at a pressure of the ambient air lower in comparison.