Reliable cooling system for operation with a two-phase refrigerant

A cooling system (10), in particular for use on board an aircraft, comprises a first cooling circuit (12a) allowing circulation of a two-phase refrigerant therethrough, a first evaporator (14a) disposed in the first cooling circuit (12a), a first condenser (22a) disposed in the first cooling circuit (12a), and a first heat sink (29a) adapted to provide cooling energy to the first condenser (22a). The cooling system (10) further comprises a second cooling circuit (12b) allowing circulation of a two-phase refrigerant therethrough, a second evaporator (14b) disposed in the second cooling circuit (12b), a second condenser (22b) disposed in the second cooling circuit (12b), a second heat sink (29b) adapted to provide cooling energy to the second condenser (22b), and a cooling energy transfer arrangement (42) which is adapted to transfer cooling energy provided by the first heat sink (29a) and/or the first condenser (22a) to the second cooling circuit (12b) or to transfer cooling energy provided by the second heat sink (29b) and/or the second condenser (22b) to the first cooling circuit (12a).