The Supersonic Transport represents a quantum step in civil aeronautics. It will cruise at altitudes having low ambient gaseous pressures far exceeding human capacities for compensatory respiration. In consideration of this evolutionary step, tentative airworthiness standards with respect to SST pressurization capabilities in the event of depressurization emergencies are discussed and a series of evolved SST cabin altitude-time profiles, together with the basis of their development, are then presented.