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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§ 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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