CS 25.107 Take-off speeds

ED Decision 2016/010/R

(a)     V₁ must be established in relation to V_EF as follows:

(1)     V_EF is the calibrated airspeed at which the critical engine is assumed to fail. V_EF must be selected by the applicant, but may not be less than V_MCG determined under CS 25.149(e).

(2)     V₁, in terms of calibrated airspeed, is selected by the applicant; however, V₁ may not be less than V_EF plus the speed gained with the critical engine inoperative during the time interval between the instant at which the critical engine is failed, and the instant at which the pilot recognises and reacts to the engine failure, as indicated by the pilot’s initiation of the first action (e.g. applying brakes, reducing thrust, deploying speed brakes) to stop the aeroplane during accelerate-stop tests.

(b)     V_2MIN, in terms of calibrated airspeed, may not be less than –

(1)     1·13 V_SR for –

(i)      Two-engined and three-engined turbo-propeller powered aeroplanes; and

(ii)     Turbojet powered aeroplanes without provisions for obtaining a significant reduction in the one-engineinoperative power-on stall speed;

(2)     1·08 V_SR for –

(i)      Turbo-propeller powered aeroplanes with more than three engines; and

(ii)     Turbojet powered aeroplanes with provisions for obtaining a significant reduction in the one-engine-inoperative power-on stall speed: and

(3)     1·10 times V_MC established under CS 25.149.

(c)      V₂, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by CS 25.121(b) but may not be less than –

(1)     V_2MIN;

(2)     V_R plus the speed increment attained (in accordance with CS 25.111(c)(2)) before reaching a height of 11 m (35 ft) above the takeoff surface; and

(3)     A speed that provides the manoeuvring capability specified in CS 25.143(h).

(d)     V_MU is the calibrated airspeed at and above which the aeroplane can safely lift off the ground, and continue the take-off. V_MU speeds must be selected by the applicant throughout the range of thrust-to-weight ratios to be certificated. These speeds may be established from free air data if these data are verified by ground take-off tests. (See AMC 25.107(d).)

(e)     V_R, in terms of calibrated air speed, must be selected in accordance with the conditions of sub-paragraphs (1) to (4) of this paragraph:

(1)     V_R may not be less than –

(i)      V₁;

(ii)     105% of V_MC;

(iii)     The speed (determined in accordance with CS 25.111(c)(2)) that allows reaching V₂ before reaching a height of 11 m (35 ft) above the take-off surface; or

(iv)     A speed that, if the aeroplane is rotated at its maximum practicable rate, will result in a V_LOF of not less than -

(A)     110% of V_MU in the allengines-operating condition, and 105% of V_MU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition; or

(B)     If the V_MU attitude is limited by the geometry of the aeroplane (i.e., tail contact with the runway), 108% of V_MU in the all-engines-operating condition and 104% of V_MU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition. (See AMC 25.107(e)(1)(iv).)

(2)     For any given set of conditions (such as weight, configuration, and temperature), a single value of V_R, obtained in accordance with this paragraph, must be used to show compliance with both the one-engine-inoperative and the all-engines-operating take-off provisions.

(3)     It must be shown that the one-engine-inoperative take-off distance, using a rotation speed of 9.3 km/h (5 knots) less than V_R established in accordance with sub-paragraphs (e)(1) and (2) of this paragraph, does not exceed the corresponding one-engine-inoperative take-off distance using the established V_R. The take-off distances must be determined in accordance with CS 25.113(a)(1). (See AMC 25.107(e)(3).)

(4)     Reasonably expected variations in service from the established take-off procedures for the operation of the aeroplane (such as over-rotation of the aeroplane and out-of-trim conditions) may not result in unsafe flight characteristics or in marked increases in the scheduled take-off distances established in accordance with CS 25.113(a). (See AMC No. 1 to CS 25.107(e)(4) and AMC No. 2 to CS 25.107(e)(4).)

(f)      V_LOF is the calibrated airspeed at which the aeroplane first becomes airborne.

(g)     V_FTO, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by CS 25.121(c), but may not be less than –

(1)     1.18 V_SR; and

(2)     A speed that provides the manoeuvring capability specified in CS 25.143(h).

(h)     In determining the take-off speeds V₁, V_R, and V₂ for flight in icing conditions, the values of V_MCG, V_MC, and V_MU determined for non-icing conditions may be used.

[Amdt 25/3]

[Amdt 25/18]