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210 

14 CFR Ch. I (1–1–24 Edition) 

§ 25.107 

(ii) The degradation of the gradient 

of climb determined in accordance with 
§ 25.121(b) is greater than one-half of 
the applicable actual-to-net takeoff 
flight path gradient reduction defined 
in § 25.115(b). 

(b) No takeoff made to determine the 

data required by this section may re-
quire exceptional piloting skill or 
alertness. 

(c) The takeoff data must be based 

on— 

(1) In the case of land planes and am-

phibians: 

(i) Smooth, dry and wet, hard-sur-

faced runways; and 

(ii) At the option of the applicant, 

grooved or porous friction course wet, 
hard-surfaced runways. 

(2) Smooth water, in the case of sea-

planes and amphibians; and 

(3) Smooth, dry snow, in the case of 

skiplanes. 

(d) The takeoff data must include, 

within the established operational lim-
its of the airplane, the following oper-
ational correction factors: 

(1) Not more than 50 percent of nomi-

nal wind components along the takeoff 
path opposite to the direction of take-
off, and not less than 150 percent of 
nominal wind components along the 
takeoff path in the direction of takeoff. 

(2) Effective runway gradients. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–92, 63 FR 8318, Feb. 18, 
1998; Amdt. 25–121, 72 FR 44665, Aug. 8, 2007; 
Amdt. 25–140, 79 FR 65525, Nov. 4, 2014] 

§ 25.107

Takeoff speeds. 

(a) V

1

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 appli-

cant, but may not be less than V

MCG

de-

termined under § 25.149(e). 

(2) V

1

, in terms of calibrated air-

speed, is selected by the applicant; 
however, V

1

may not be less than V

EF

 

plus the speed gained with critical en-
gine inoperative during the time inter-
val between the instant at which the 
critical engine is failed, and the in-
stant at which the pilot recognizes and 
reacts to the engine failure, as indi-
cated by the pilot’s initiation of the 
first action (e.g., applying brakes, re-
ducing thrust, deploying speed brakes) 

to stop the airplane during accelerate- 
stop tests. 

(b) 

V

2MIN,

in terms of calibrated air-

speed, may not be less than— 

(1) 1.13 

V

SR

for— 

(i) Two-engine and three-engine tur-

bopropeller and reciprocating engine 
powered airplanes; and 

(ii) Turbojet powered airplanes with-

out provisions for obtaining a signifi-
cant reduction in the one-engine-inop-
erative power-on stall speed; 

(2) 1.08 

V

SR

for— 

(i) Turbopropeller and reciprocating 

engine powered airplanes with more 
than three engines; and 

(ii) Turbojet powered airplanes with 

provisions for obtaining a significant 
reduction in the one-engine-inoper-
ative power-on stall speed; and 

(3) 1.10 times 

V

MC

established under 

§ 25.149. 

(c) 

V

2

, in terms of calibrated air-

speed, must be selected by the appli-
cant to provide at least the gradient of 
climb required by § 25.121(b) but may 
not be less than— 

(1) V

2MIN

(2) 

V

R

plus the speed increment at-

tained (in accordance with § 25.111(c)(2)) 
before reaching a height of 35 feet 
above the takeoff surface; and 

(3) A speed that provides the maneu-

vering capability specified in § 25.143(h). 

(d) V

MU

is the calibrated airspeed at 

and above which the airplane can safe-
ly lift off the ground, and con- tinue 
the takeoff. V

MU

speeds must be se-

lected by the applicant throughout the 
range of thrust-to-weight ratios to be 
certificated. These speeds may be es-
tablished from free air data if these 
data are verified by ground takeoff 
tests. 

(e) 

V

R,

in terms of calibrated air-

speed, must be selected in accordance 
with the conditions of paragraphs (e)(1) 
through (4) of this section: 

(1) 

V

R

may not be less than— 

(i) 

V

1

(ii) 105 percent of 

V

MC

(iii) The speed (determined in accord-

ance with § 25.111(c)(2)) that allows 
reaching 

V

2

before reaching a height of 

35 feet above the takeoff surface; or 

(iv) A speed that, if the airplane is 

rotated at its maximum practicable 
rate, will result in a V

LOF

of not less 

than — 

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211 

Federal Aviation Administration, DOT 

§ 25.109 

(A) 110 percent of V

MU

in the all-en-

gines-operating condition, and 105 per-
cent 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 airplane (

i.e.,  tail 

contact with the runway), 108 percent 
of V

MU

in the all-engines-operating 

condition, and 104 percent of V

MU

deter-

mined at the thrust-to-weight ratio 
corresponding to the one-engine-inop-
erative condition. 

(2) For any given set of conditions 

(such as weight, configuration, and 
temperature), a single value of 

V

R,

ob-

tained in accordance with this para-
graph, must be used to show compli-
ance with both the one-engine-inoper-
ative and the all-engines-operating 
takeoff provisions. 

(3) It must be shown that the one-en-

gine-inoperative takeoff distance, 
using a rotation speed of 5 knots less 
than 

V

R

established in accordance with 

paragraphs (e)(1) and (2) of this section, 
does not exceed the corresponding one- 
engine-inoperative takeoff distance 
using the established 

V

R

. The takeoff 

distances must be determined in ac-
cordance with § 25.113(a)(1). 

(4) Reasonably expected variations in 

service from the established takeoff 
procedures for the operation of the air-
plane (such as over-rotation of the air-
plane and out-of-trim conditions) may 
not result in unsafe flight characteris-
tics or in marked increases in the 
scheduled takeoff distances established 
in accordance with § 25.113(a). 

(f) 

V

LOF

is the calibrated airspeed at 

which the airplane first becomes air-
borne. 

(g) 

V

FTO

, in terms of calibrated air-

speed, must be selected by the appli-
cant to provide at least the gradient of 
climb required by § 25.121(c), but may 
not be less than— 

(1) 1.18 

V

SR

; and 

(2) A speed that provides the maneu-

vering capability specified in § 25.143(h). 

(h) In determining the takeoff speeds 

V

1

, V

R

, and V

2

for flight in icing condi-

tions, the values of V

MCG

, V

MC

, and V

MU

 

determined for non-icing conditions 
may be used. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–38, 41 FR 55466, Dec. 20, 
1976; Amdt. 25–42, 43 FR 2320, Jan. 16, 1978; 
Amdt. 25–92, 63 FR 8318, Feb. 18, 1998; Amdt. 
25–94, 63 FR 8848, Feb. 23, 1998; Amdt. 25–108, 
67 FR 70826, Nov. 26, 2002; Amdt. 25–121, 72 FR 
44665, Aug. 8, 2007; Amdt. 25–135, 76 FR 74654, 
Dec. 1, 2011] 

§ 25.109

Accelerate-stop distance. 

(a) The accelerate-stop distance on a 

dry runway is the greater of the fol-
lowing distances: 

(1) The sum of the distances nec-

essary to— 

(i) Accelerate the airplane from a 

standing start with all engines oper-
ating to V

EF

for takeoff from a dry run-

way; 

(ii) Allow the airplane to accelerate 

from V

EF

to the highest speed reached 

during the rejected takeoff, assuming 
the critical engine fails at V

EF

and the 

pilot takes the first action to reject 
the takeoff at the V

1

for takeoff from a 

dry runway; and 

(iii) Come to a full stop on a dry run-

way from the speed reached as pre-
scribed in paragraph (a)(1)(ii) of this 
section; plus 

(iv) A distance equivalent to 2 sec-

onds at the V

1

for takeoff from a dry 

runway. 

(2) The sum of the distances nec-

essary to— 

(i) Accelerate the airplane from a 

standing start with all engines oper-
ating to the highest speed reached dur-
ing the rejected takeoff, assuming the 
pilot takes the first action to reject 
the takeoff at the V

1

for takeoff from a 

dry runway; and 

(ii) With all engines still operating, 

come to a full stop on dry runway from 
the speed reached as prescribed in para-
graph (a)(2)(i) of this section; plus 

(iii) A distance equivalent to 2 sec-

onds at the V

1

for takeoff from a dry 

runway. 

(b) The accelerate-stop distance on a 

wet runway is the greater of the fol-
lowing distances: 

(1) The accelerate-stop distance on a 

dry runway determined in accordance 
with paragraph (a) of this section; or 

(2) The accelerate-stop distance de-

termined in accordance with paragraph 

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