A system (10) for cooling a thermally loaded device on board an aircraft comprises a distribution line (12) which is in communication with an installation space (14) of the thermally loaded device, a coolant supply line (20) which is in communication with a coolant source, and a heat removal line (28) which is in communication with a source of pressure below atmospheric pressure. A shut-off control device (34) is adapted so as, in a first position, to separate the distribution line (12) from the coolant supply line (20) and connect the distribution line (12) to the heat removal line (28) and, in a second position, to connect the distribution line (12) to the coolant supply line (20) and separate the distribution line (12) from the heat removal line (28).