215 

Federal Aviation Administration, DOT 

§ 25.119 

(b) Takeoff distance on a wet runway 

is the greater of— 

(1) The takeoff distance on a dry run-

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

(2) The horizontal distance along the 

takeoff path from the start of the take-
off to the point at which the airplane is 
15 feet above the takeoff surface, 
achieved in a manner consistent with 
the achievement of V

2

before reaching 

35 feet above the takeoff surface, deter-
mined under § 25.111 for a wet runway. 

(c) If the takeoff distance does not in-

clude a clearway, the takeoff run is 
equal to the takeoff distance. If the 
takeoff distance includes a clearway— 

(1) The takeoff run on a dry runway 

is the greater of— 

(i) The horizontal distance along the 

takeoff path from the start of the take-
off to a point equidistant between the 
point at which V

LOF

is reached and the 

point at which the airplane is 35 feet 
above the takeoff surface, as deter-
mined under § 25.111 for a dry runway; 
or 

(ii) 115 percent of the horizontal dis-

tance along the takeoff path, with all 
engines operating, from the start of the 
takeoff to a point equidistant between 
the point at which V

LOF

is reached and 

the point at which the airplane is 35 
feet above the takeoff surface, deter-
mined by a procedure consistent with 
§ 25.111. 

(2) The takeoff run on a wet runway 

is the greater of— 

(i) The horizontal distance along the 

takeoff path from the start of the take-
off to the point at which the airplane is 
15 feet above the takeoff surface, 
achieved in a manner consistent with 
the achievement of V

2

before reaching 

35 feet above the takeoff surface, as de-
termined under § 25.111 for a wet run-
way; or 

(ii) 115 percent of the horizontal dis-

tance along the takeoff path, with all 
engines operating, from the start of the 
takeoff to a point equidistant between 
the point at which V

LOF

is reached and 

the point at which the airplane is 35 
feet above the takeoff surface, deter-
mined by a procedure consistent with 
§ 25.111. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–23, 35 FR 5671, Apr. 8, 
1970; Amdt. 25–92, 63 FR 8320, Feb. 18, 1998] 

§ 25.115

Takeoff flight path. 

(a) The takeoff flight path shall be 

considered to begin 35 feet above the 
takeoff surface at the end of the take-
off distance determined in accordance 
with § 25.113(a) or (b), as appropriate for 
the runway surface condition. 

(b) The net takeoff flight path data 

must be determined so that they rep-
resent the actual takeoff flight paths 
(determined in accordance with § 25.111 
and with paragraph (a) of this section) 
reduced at each point by a gradient of 
climb equal to— 

(1) 0.8 percent for two-engine air-

planes; 

(2) 0.9 percent for three-engine air-

planes; and 

(3) 1.0 percent for four-engine air-

planes. 

(c) The prescribed reduction in climb 

gradient may be applied as an equiva-
lent reduction in acceleration along 
that part of the takeoff flight path at 
which the airplane is accelerated in 
level flight. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–92, 63 FR 8320, Feb. 18, 
1998] 

§ 25.117

Climb: general. 

Compliance with the requirements of 

§§ 25.119 and 25.121 must be shown at 
each weight, altitude, and ambient 
temperature within the operational 
limits established for the airplane and 
with the most unfavorable center of 
gravity for each configuration. 

§ 25.119

Landing climb: All-engines-op-

erating. 

In the landing configuration, the 

steady gradient of climb may not be 
less than 3.2 percent, with the engines 
at the power or thrust that is available 
8 seconds after initiation of movement 
of the power or thrust controls from 
the minimum flight idle to the go- 
around power or thrust setting— 

(a) In non-icing conditions, with a 

climb speed of V

REF

determined in ac-

cordance with § 25.125(b)(2)(i); and 

(b) In icing conditions with the most 

critical of the landing ice accretion(s) 
defined in Appendices C and O of this 
part, as applicable, in accordance with 
§ 25.21(g), and with a climb speed of 

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216 

14 CFR Ch. I (1–1–24 Edition) 

§ 25.121 

V

REF

determined in accordance with 

§ 25.125(b)(2)(ii). 

[Amdt. 25–121, 72 FR 44666; Aug. 8, 2007, as 
amended by Amdt. 25–,140, 79 FR 65525, Nov. 
4, 2014] 

§ 25.121

Climb: One-engine-inoper-

ative. 

(a) 

Takeoff; landing gear extended. In 

the critical takeoff configuration exist-
ing along the flight path (between the 
points at which the airplane reaches 
V

LOF

and at which the landing gear is 

fully retracted) and in the configura-
tion used in § 25.111 but without ground 
effect, the steady gradient of climb 
must be positive for two-engine air-
planes, and not less than 0.3 percent for 
three-engine airplanes or 0.5 percent 
for four-engine airplanes, at 

V

LOF

and 

with— 

(1) The critical engine inoperative 

and the remaining engines at the power 
or thrust available when retraction of 
the landing gear is begun in accordance 
with § 25.111 unless there is a more crit-
ical power operating condition existing 
later along the flight path but before 
the point at which the landing gear is 
fully retracted; and 

(2) The weight equal to the weight 

existing when retraction of the landing 
gear is begun, determined under 
§ 25.111. 

(b) 

Takeoff; landing gear retracted. In 

the takeoff configuration existing at 
the point of the flight path at which 
the landing gear is fully retracted, and 
in the configuration used in § 25.111 but 
without ground effect: 

(1) The steady gradient of climb may 

not be less than 2.4 percent for two-en-
gine airplanes, 2.7 percent for three-en-
gine airplanes, and 3.0 percent for four- 
engine airplanes, at V

2

with: 

(i) The critical engine inoperative, 

the remaining engines at the takeoff 
power or thrust available at the time 
the landing gear is fully retracted, de-
termined under § 25.111, unless there is 
a more critical power operating condi-
tion existing later along the flight path 
but before the point where the airplane 
reaches a height of 400 feet above the 
takeoff surface; and 

(ii) The weight equal to the weight 

existing when the airplane’s landing 
gear is fully retracted, determined 
under § 25.111. 

(2) The requirements of paragraph 

(b)(1) of this section must be met: 

(i) In non-icing conditions; and 
(ii) In icing conditions with the most 

critical of the takeoff ice accretion(s) 
defined in Appendices C and O of this 
part, as applicable, in accordance with 
§ 25.21(g), if in the configuration used to 
show compliance with § 25.121(b) with 
this takeoff ice accretion: 

(A) The stall speed at maximum 

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

SR

; or 

(B) 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). 

(c) 

Final takeoff. In the en route con-

figuration at the end of the takeoff 
path determined in accordance with 
§ 25.111: 

(1) The steady gradient of climb may 

not be less than 1.2 percent for two-en-
gine airplanes, 1.5 percent for three-en-
gine airplanes, and 1.7 percent for four- 
engine airplanes, at V

FTO

with— 

(i) The critical engine inoperative 

and the remaining engines at the avail-
able maximum continuous power or 
thrust; and 

(ii) The weight equal to the weight 

existing at the end of the takeoff path, 
determined under § 25.111. 

(2) The requirements of paragraph 

(c)(1) of this section must be met: 

(i) In non-icing conditions; and 
(ii) In icing conditions with the most 

critical of the final takeoff ice accre-
tion(s) defined in Appendices C and O of 
this part, as applicable, in accordance 
with § 25.21(g), if in the configuration 
used to show compliance with § 25.121(b) 
with the takeoff ice accretion used to 
show compliance with § 25.111(c)(5)(i): 

(A) The stall speed at maximum 

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

SR

; or 

(B) 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). 

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