FAA Federal Aviation Regulations (FARS, 14 CFR)

A rough air speed, VRA, for use as the recommended turbulence penetration airspeed in §25.1585(a)(8), must be established, which --

(1) Is not greater than the design airspeed for maximum gust intensity, selected for VB; and

(2) Is not less than the minimum value of VB specified in §25.335(d); and

(3) Is sufficiently less than VMO to ensure that likely speed variation during rough air encounters will not cause the overspeed warning to operate too frequently. In the absence of a rational investigation substantiating the use of other values, VRA must be less than VMO -- 35 knots (TAS).

[Doc. No. 27902, 61 FR 5222, Feb. 9, 1996]