§3.757 Air-speed indicator.

(a) True indicated air speed shall be used: (1) The never-exceed speed, Vne—a radial red line (see § 3.739). red line in (1) above to the upper limit of the (2) The caution range—a yellow arc extending from the red line in (1) above to the upper limit of the green arc specified in (3) below. (3) The normal operating range—a green arc with the lower limit at Vs1, as determined in § 3.82 with maximum weight, landing gear and wing flaps retracted, and the upper limit at the maximum structural cruising speed established in § 3.740. (4) The flap operating range—a white arc with the lower limit at Vso as determined in § 3.82 at the maximum weight, and the upper limit at the flaps-extended speed in § 3.742. (b) When the never-exceed and maximum structural cruising speeds vary with altitude, means shall be provided which will indicate the appropriate limitations to the pilot throughout the operating altitude range.