§ 25.1517 Rough air speed, VRA.
- (a) A rough air speed, VRA, for use as the recommended turbulence penetration airspeed, and a rough air Mach number, MRA, for use as the recommended turbulence penetration Mach number, must be established. VRA/MRA must be sufficiently less than VMO/MMO to ensure that likely speed variation during rough air encounters will not cause the overspeed warning to operate too frequently.
- (b) At altitudes where VMO is not limited by Mach number, in the absence of a rational investigation substantiating the use of other values, VRA must be less than VMO minus 35 KTAS.
- (c) At altitudes where VMO is limited by Mach number, MRA 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. 25-148, 87 FR 75710, Dec. 9, 2022; 88 FR 2813, Jan. 18, 2023]