This Aeronautical Standard establishes the essential minimum safe requirements for pitot-static type of Maximum Allowable Airspeed Instruments primarily for use in reciprocating engine powered civil transport aircraft, the operation of which may subject the instruments to the instruments to the environmental conditions specified in paragraph 3.3. This Aeronautical Standard covers the basic types of maximum allowable airspeed instruments which give a continuous indication of both indicated air speed and maximum allowable airspeed not exceeding 650 knots.