CS 25.207 Stall warning

• ED Decision 2016/010/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

CS 25.207 Stall warning ED Decision 2016/010/R (a) Stall warning with sufficient margin to prevent inadvertent stalling with the flaps and landing gear in any normal position must be clear and distinctive to the pilot in straight and turning flight. (b) The warning must be furnished either through the inherent aerodynamic qualities of the aeroplane or by a device that will give clearly distinguishable indications under expected conditions of flight. However, a visual stall warning device that requires the attention of the crew within the cockpit is not acceptable by itself. If a warning device is used, it must provide a warning in each of the aeroplane configurations prescribed in sub-paragraph (a) of this paragraph at the speed prescribed in sub-paragraphs (c) and (d) of this paragraph. Except for the stall warning prescribed in subparagraph (h)(3)(ii) of this paragraph, the stall warning for flight in icing conditions must be provided by the same means as the stall warning for flight in non-icing conditions. (See [AMC 25.207(b)](#_DxCrossRefBm1709820875).) (c) When the speed is reduced at rates not exceeding 0.5 m/s2 (one knot per second), stall warning must begin, in each normal configuration, at a speed, VSW, exceeding the speed at which the stall is identified in accordance with [CS 25.201(d)](#_DxCrossRefBm1709820668) by not less than 9.3 km/h (five knots) or five percent CAS, whichever is greater. Once initiated, stall warning must continue until the angle of attack is reduced to approximately that at which stall warning began. (See [AMC 25.207(c) and (d)](#_DxCrossRefBm1709820874)). (d) In addition to the requirement of subparagraph(c) of this paragraph, when the speed is reduced at rates not exceeding 0.5 m/s2 (one knot per second), in straight flight with engines idling and at the centre-of-gravity position specified in [CS 25.103(b)(5)](#_DxCrossRefBm1709820692), VSW, in each normal configuration, must exceed VSR by not less than 5.6 km/h (three knots) or three percent CAS, whichever is greater. (See [AMC 25.207(c) and (d)](#_DxCrossRefBm1709820874)). (e) In icing conditions, the stall warning margin in straight and turning flight must be sufficient to allow the pilot to prevent stalling (as defined in [CS 25.201(d)](#_DxCrossRefBm1709820668)) when the pilot starts a recovery manoeuvre not less than three seconds after the onset of stall warning. When demonstrating compliance with this paragraph, the pilot must perform the recovery manoeuvre in the same way as for the airplane in non-icing conditions. Compliance with this requirement must be demonstrated in flight with the speed reduced at rates not exceeding 0.5 m/sec2 (one knot per second), with – (1) The most critical of the take-off ice and final take-off ice accretions defined in Appendices C and O, as applicable, in accordance with [CS 25.21(g)](#_DxCrossRefBm1709820660), for each configuration used in the take-off phase of flight; (2) The most critical of the en route ice accretion(s) defined in Appendices C and O, as applicable, in accordance with [CS 25.21(g)](#_DxCrossRefBm1709820660), for the en route configuration; (3) The most critical of the holding ice accretion(s) defined in Appendices C and O, as applicable, in accordance with [CS 25.21(g)](#_DxCrossRefBm1709820660), for the holding configuration(s); (4) The most critical of the approach ice accretion(s) defined in Appendices C and O, as applicable, in accordance with [CS 25.21(g)](#_DxCrossRefBm1709820660), for the approach configuration(s); and (5) The most critical of the landing ice accretion(s) defined in Appendices C and O, as applicable, in accordance with [CS 25.21(g)](#_DxCrossRefBm1709820660), for the landing and go-around configuration(s). (f) The stall warning margin must be sufficient in both non-icing and icing conditions to allow the pilot to prevent stalling when the pilot starts a recovery manoeuvre not less than one second after the onset of stall warning in slowdown turns with at least 1.5g load factor normal to the flight path and airspeed deceleration rates of at least 1 m/sec2 (2 knots per second), When demonstrating compliance with this paragraph for icing conditions, the pilot must perform the recovery manoeuvre in the same way as for the airplane in non-icing conditions. Compliance with this requirement must be demonstrated in flight with – (1) The flaps and landing gear in any normal position; (2) The aeroplane trimmed for straight flight at a speed of 1.3 VSR; and (3) The power or thrust necessary to maintain level flight at 1.3 VSR. (g) Stall warning must also be provided in each abnormal configuration of the high lift devices that is likely to be used in flight following system failures (including all configurations covered by Aeroplane Flight Manual procedures). (h) The following stall warning margin is required for flight in icing conditions before the ice protection system has been activated and is performing its intended function. Compliance must be shown using the most critical of the ice accretion(s) defined in [Appendix C, part II(e)](#_DxCrossRefBm1709820680), and [Appendix O, part II(d)](#_DxCrossRefBm1709820664), as applicable, in accordance with CS 25.21(g). The stall warning margin in straight and turning flight must be sufficient to allow the pilot to prevent stalling without encountering any adverse flight characteristics when: (1) The speed is reduced at rates not exceeding 0.5 m/sec² (one knot per second); (2) The pilot performs the recovery manoeuvre in the same way as for flight in non-icing conditions; and (3) The recovery manoeuvre is started no earlier than: (i) One second after the onset of stall warning if stall warning is provided by the same means as for flight in non-icing conditions; or (ii) Three seconds after the onset of stall warning if stall warning is provided by a different means than for flight in non-icing conditions. (i) In showing compliance with subparagraph (h) of this paragraph, if stall warning is provided by a different means in icing conditions than for non-icing conditions, compliance with [CS 25.203](#_DxCrossRefBm1709820862) must be shown using the accretion defined in appendix C, [part II(e)](#_DxCrossRefBm1709820664). Compliance with this requirement must be shown using the demonstration prescribed by [CS 25.201](#_DxCrossRefBm1709820668), except that the deceleration rates of CS 25.201(c)(2) need not be demonstrated. [Amdt 25/3] [Amdt 25/7] [Amdt 25/16] [Amdt 25/18]