The present invention relates to an air-conditioning system, in particular for the air conditioning of an airplane cabin, comprising at least two air-conditioning plants which are in communication in each case on the inlet side with a supply line and on the outlet side with a cabin to be air conditioned or with a mixing chamber, with the supply line on the inlet side having at least one flow regulating valve in each case for the purpose of regulating the flow. A high redundancy with low losses in performance and with optimum costs and weight is achieved in that downstream of the flow regulating valves at least one connection line is provided which connects the supply lines on the inlet side or the air-conditioning plants on the pressurized air side to one another and which is provided with a valve, by means of which the connection line can be opened or closed in dependence on the valve position.