Rough air speed, VRA.

§ 25.1517 Rough air speed, V RA. (a) A rough air speed, V RA, for use as the recommended turbulence penetration airspeed, and a rough air Mach number, M RA , for use as the recommended turbulence penetration Mach number, must be established. V RA /M RA must be sufficiently less than V MO /M MO to ensure that likely speed variation during rough air encounters will not cause the overspeed warning to operate too frequently. (b) At altitudes where V MO is not limited by Mach number, in the absence of a rational investigation substantiating the use of other values, V RA must be less than V MO minus 35 KTAS. (c) At altitudes where V MO is limited by Mach number, M RA may be chosen to provide an optimum margin between low and high speed buffet boundaries. [Amdt. 25-141, 79 FR 73469, Dec. 11, 2014, as amended by FAA-2022-1355; Amdt. No. 25-146, 87 FR 75710, Dec. 9, 2022]