This specification covers the types of oxygen masks considered satisfactory for use in commercial transport aircraft at altitudes up to 25@000 ft. The types of masks covered are: Continuous Flow (a) Nasal (b ) Oro-nasal (c) Full-face Demand Flow (a) Nasal (b) Oro-nasal (c) Full-face PURPOSE: To specify minimum requirements for the design@ construction and performance of oxygen masks to be used in commercial transport aircraft.