This standard specifies test methods for transport packages and unit loads under simulated high-altitude or plateau low-pressure environments. The standard details equipment requirements, procedures, and result evaluation methods, primarily applicable to the performance assessment of packages for air transport (especially for non-pressurized aircraft with flight altitudes not exceeding 3,500 meters). It may also be referenced for packages used in high-altitude ground transportation. The method involves placing the package inside a pressure test chamber, reducing the pressure to a specified value and maintaining it for a predetermined duration to evaluate its resistance to low pressure and its ability to protect the contents. The core instrument for conducting this test is a low-pressure test chamber capable of precisely controlling and maintaining low-pressure conditions, which should simulate the altitude and pressure specified by the standard. Some tests may also require the use of a digital vacuum gauge capable of monitoring pressure.