---
title: "CS 25.1517 Rough air speed, VRA — CS-25 · Avioverse"
description: "A rough air speed, VRA for use as the recommended turbulence penetration air speed, and a rough air Mach number MRA, for use as the recommended…"
url: "https://avioverse.aero/regulations/easa/cs-25/subpart-g/cs-25-1517"
---

# CS 25.1517 Rough air speed, VRA

Large Aeroplanes (CS-25) · CS-25 · EAR revision 26 Jan 2023

IR Implementing rule

## CS 25.1517 Rough air speed, VRA

(a) A rough air speed, VRA for use as the recommended turbulence penetration air speed, and a rough air Mach number MRA, for use as the recommended turbulence penetration Mach number, must be established 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 - 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 25/1]

IR · CS 25.1517 — CS-25 · ED Decision 2005/006/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

[All rules in SUBPART G – OPERATING LIMITATIONS AND INFORMATION](https://avioverse.aero/regulations/easa/cs-25/subpart-g)

Consolidated from the EASA Easy Access Rules (revision 26 Jan 2023, extracted 13 Oct 2026) for convenience. Not the official publication — verify against the Official Journal of the European Union and the EASA publications before operational use.