217 

Federal Aviation Administration, DOT 

§ 25.121 

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). 

(d) 

Approach. 

In a configuration cor-

responding to the normal all-engines- 
operating procedure in which V

SR

for 

this configuration does not exceed 110 
percent of the V

SR

for the related all- 

engines-operating landing configura-
tion: 

(1) The steady gradient of climb may 

not be less than 2.1 percent for two-en-
gine airplanes, 2.4 percent for three-en-
gine airplanes, and 2.7 percent for four- 
engine airplanes, with— 

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