210 

14 CFR Ch. I (1–1–19 Edition) 

§ 25.105 

(3) The airplane in other respects 

(such as flaps, landing gear, and ice ac-
cretions) in the condition existing in 
the test or performance standard in 
which V

SR

is being used; 

(4) The weight used when V

SR

is being 

used as a factor to determine compli-
ance with a required performance 
standard; 

(5) The center of gravity position 

that results in the highest value of ref-
erence stall speed; and 

(6) The airplane trimmed for straight 

flight at a speed selected by the appli-
cant, but not less than 1.13V

SR

and not 

greater than 1.3V

SR

. 

(c) Starting from the stabilized trim 

condition, apply the longitudinal con-
trol to decelerate the airplane so that 
the speed reduction does not exceed 
one knot per second. 

(d) In addition to the requirements of 

paragraph (a) of this section, when a 
device that abruptly pushes the nose 
down at a selected angle of attack (e.g., 
a stick pusher) is installed, the ref-
erence stall speed, V

SR

, may not be less 

than 2 knots or 2 percent, whichever is 
greater, above the speed at which the 
device operates. 

[Doc. No. 28404, 67 FR 70825, Nov. 26, 2002, as 
amended by Amdt. 25–121, 72 FR 44665, Aug. 8, 
2007] 

§ 25.105

Takeoff. 

(a) The takeoff speeds prescribed by 

§ 25.107, the accelerate-stop distance 
prescribed by § 25.109, the takeoff path 
prescribed by § 25.111, the takeoff dis-
tance and takeoff run prescribed by 
§ 25.113, and the net takeoff flight path 
prescribed by § 25.115, must be deter-
mined in the selected configuration for 
takeoff at each weight, altitude, and 
ambient temperature within the oper-
ational limits selected by the appli-
cant— 

(1) In non-icing conditions; and 
(2) In icing conditions, if in the con-

figuration used to show compliance 
with § 25.121(b), and with the most crit-
ical of the takeoff ice accretion(s) de-
fined in appendices C and O of this 
part, as applicable, in accordance with 
§ 25.21(g): 

(i) The stall speed at maximum take-

off weight exceeds that in non-icing 
conditions by more than the greater of 
3 knots CAS or 3 percent of V

SR

; or 

(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) 

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