This International Standard, which is applicable primarily to civil and transport aircraft, specifies the test requirements for aerospace equipment which could be subjected to moisture ingress, frosting and condensation, resulting from the passage through atmospheric conditions of high humidity, in combination with or induced by changing temperature and pressure. It specifies various test procedures which can be invoked when required by an equipment design and requirement specification. This International Standard permits the selection of specific test conditions and methods that define acceptance requirements for aerospace equipment which may be subject to induced condensation and humidity. The conditions are more likely to occur in an unconditioned bay but may also occur in a conditioned bay when the equipment has a short thermal transmission path to an external airframe structure. The incidence of this form of condensation is also influenced by the duty cycle of the equipment and its thermal characteristics. This test is not intended to reveal the defects ensuing from prolonged exposure to high humidity such as may occur on the ground in tropical climates, a suitable test for this environment is given in ISO 7137. Also this test is not intended to simulate the hazards of local ice formation, in which case reference should be made to the icing tests defined in ISO 7137, test procedure 1.4.