The invention relates to a device and a method for distributing air in a cargo aircraft. The cargo aircraft has an air 
distribution system (10) which is connected to at least one cargo 
deck. The air 
distribution system comprises a source (12, 14, 16, 18) for 
bleed air, at least one so-called 
air conditioning unit (28, 38) for treating the 
bleed air, a mixing unit (32) which receives treated 
bleed air from the 
air conditioning unit (28, 38) and delivers it to the at least one cargo 
deck, and at least one shut-off valve (58, 60, 62, 64) between the mixing unit (32) and the cargo 
deck in order to interrupt or completely release the air supply to the cargo deck. In order to reduce the bleed air requirement, a 
cockpit switch (82, 84, 86, 88) co-operating with the shutoff valve is provided, the operation of which switch causes the at least one shutoff valve (58, 60, 62, 64) to take up an intermediate position. For this purpose the shutoff valve (58, 60, 62, 64) is formed as a motor-operated control valve which can take up any desired intermediate position between its completely open and completely closed position. A 
control unit (92) establishes for each possible operating state of the air 
distribution system a desired 
air volume balance and adjusts the flow volume through the at least one 
air conditioning unit (28, 38) in accordance with the desired 
air volume balance established for the respective operating state such that the pressure in the mixing unit (32) is at a constant, predetermined value.