This SAE Aerospace Information Report (AIR) provides data and general analysis methods for calculation of internal and external@ pressurized and unpressurized airplane compartment pressures during rapid discharge of cabin pressure. References to the applicable current FAA and EASA rules and advisory material are provided. While rules and interpretations can be expected to evolve@ numerous airplanes have been approved under current and past rules that will have a continuing need for analysis of production and field modifications@ alterations and repairs. The data and basic principles provided by this report are adaptable to any compartment decompression analysis requirement. Purpose The purpose of this report is to provide a method to predict transient differential pressures across internal pressure barriers (such as floor panels and bulkheads)@ within external compartments adjacent to the pressure vessel (such as fairings and tailcone) and the occupied compartment pressure altitudes resulting from cabin decompression events prescribed by FAA and JAA/EASA regulations and Special Conditions. The analysis methods in this report can be used as a design tool to determine the following: The maximum permissible openings in the pressure vessel from loss of antennae@ duct couplings@ seals@ etc.@ that will limit maximum transient cabin pressure altitude to acceptable levels. If the pressure vessel opening can result from a fatigue crack@ the allowable opening size may define the required structural inspection intervals. The minimum permissible vent openings through internal partitions and structure that will limit panel pressure differentials to structurally acceptable levels during decompression events. The minimum permissible vent openings through external fairings and structure that will limit panel pressure differentials to structurally acceptable levels during decompression events. The maximum permissible cockpit door weight and door unlatching pressure to limit cockpit partition loads to acceptable levels during a cockpit structure decompression. The airplane descent rate required to limit maximum transient cabin pressure altitude to acceptable levels during emergency descent@ which may size lift dump and drag devices and their required extension/operating speed capabilities. The analysis methods in this report can also be used as a validation tool for a specified aircraft configuration. Predicted pressure differentials that would result from a decompression event for a specified airplane configuration can be used for structural analysis and substantiation. Analysis to determine cabin pressure altitudes can be used in lieu of flight testing.