This Aerospace Standard establishes essential minimum safe performance standards for pressure actuated Rate of Climb (Vertical Speed) Indicators primarily for use with turbine powered subsonic transport aircraft, the operation of which may subject the instruments to the environmental conditions specified in Section 3.3. This Aerospace Standard covers four basic types of direct reading pressure actuated rate of climb (vertical speed) indicators as follows: TYPE I - Range 0-2000 feet per minute climb and descent, TYPE II - Range 0-3000 feet per minute climb and descent, TYPE III - Range 0-4000 feet per minute climb and descent, TYPE IV - Range 0-6000 feet per minute climb and descent.