SAE AS392C : 2008

This Aeronautical Standard covers two (2) basic types of instruments as follows: TYPE I - Range 35,000 feet. Barometric Pressure. Scale range at least 28.1 - 30.99 inches of mercury (946-1049 millibars). May include markers working in conjunction with the Barometric Pressure Scale to indicate pressure altitude. TYPE II- Range 50,000 feet. Barometric Pressure. Scale range at least 28.1 - 30.99 inches of mercury (946-1049 millibars). May include markers working in conjunction with the Barometric Pressure Scale to indicate pressure altitude.

Cross Reference: NACA1235