383
Federal Aviation Administration, DOT
§ 25.125
(ii) In icing conditions with the ap-
proach ice accretion defined in appen-
dix C. The climb speed selected for non-
icing conditions may be used if the
climb speed for icing conditions, com-
puted in accordance with paragraph
(d)(1)(iii) of this section, does not ex-
ceed that for non-icing conditions by
more than the greater of 3 knots CAS
or 3 percent.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–84, 60 FR 30749, June 9,
1995; Amdt. 25–108, 67 FR 70826, Nov. 26, 2002;
Amdt. 25–121, 72 FR 44666; Aug. 8, 2007]
§ 25.123
En route flight paths.
(a) For the en route configuration,
the flight paths prescribed in para-
graph (b) and (c) of this section must
be determined at each weight, altitude,
and ambient temperature, within the
operating limits established for the
airplane. The variation of weight along
the flight path, accounting for the pro-
gressive consumption of fuel and oil by
the operating engines, may be included
in the computation. The flight paths
must be determined at a speed not less
than V
FTO
, with—
(1) The most unfavorable center of
gravity;
(2) The critical engines inoperative;
(3) The remaining engines at the
available maximum continuous power
or thrust; and
(4) The means for controlling the en-
gine-cooling air supply in the position
that provides adequate cooling in the
hot-day condition.
(b) The one-engine-inoperative net
flight path data must represent the ac-
tual climb performance diminished by
a gradient of climb of 1.1 percent for
two-engine airplanes, 1.4 percent for
three-engine airplanes, and 1.6 percent
for four-engine airplanes—
(1) In non-icing conditions; and
(2) In icing conditions with the en
route ice accretion defined in appendix
C, if:
(i) A speed of 1.18 ‘‘V
SR0
with the en
route ice accretion exceeds the en
route speed selected for non-icing con-
ditions by more than the greater of 3
knots CAS or 3 percent of V
SR
; or
(ii) The degradation of the gradient
of climb is greater than one-half of the
applicable actual-to-net flight path re-
duction defined in paragraph (b) of this
section.
(c) For three- or four-engine air-
planes, the two-engine-inoperative net
flight path data must represent the ac-
tual climb performance diminished by
a gradient of climb of 0.3 percent for
three-engine airplanes and 0.5 percent
for four-engine airplanes.
[Docket No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–121, 72 FR 44666; Aug. 8,
2007]
§ 25.125
Landing.
(a) The horizontal distance necessary
to land and to come to a complete stop
(or to a speed of approximately 3 knots
for water landings) from a point 50 feet
above the landing surface must be de-
termined (for standard temperatures,
at each weight, altitude, and wind
within the operational limits estab-
lished by the applicant for the air-
plane):
(1) In non-icing conditions; and
(2) In icing conditions with the land-
ing ice accretion defined in appendix C
if V
REF
for icing conditions exceeds V
REF
for non-icing conditions by more than 5
knots CAS at the maximum landing
weight.
(b) In determining the distance in
paragraph (a) of this section:
(1) The airplane must be in the land-
ing configuration.
(2) A stabilized approach, with a cali-
brated airspeed of not less than V
REF
,
must be maintained down to the 50-foot
height.
(i) In non-icing conditions, V
REF
may
not be less than:
(A) 1.23 V
SR
0;
(B) V
MCL
established under § 25.149(f);
and
(C) A speed that provides the maneu-
vering capability specified in § 25.143(h).
(ii) In icing conditions, V
REF
may not
be less than:
(A) The speed determined in para-
graph (b)(2)(i) of this section;
(B) 1.23 V
SR0
with the landing ice ac-
cretion defined in appendix C if that
speed exceeds V
REF
for non-icing condi-
tions by more than 5 knots CAS; and
(C) A speed that provides the maneu-
vering capability specified in § 25.143(h)
with the landing ice accretion defined
in appendix C.
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