European Aviation Safety Agency

BOOK 1
CS-25
of 11 m (35 ft) above the take-off surface;
or
(iv) A speed that, if the aeroplane is
rotated at its maximum practicable rate, will
result in a V LOF of not less than-
(A) 110% of V MU in the allengines-operating
condition,
and 105% of V MU determined
at the thrust-to-weight ratio
corresponding to the oneengine-inoperative
condition;
or
(B) If the V MU attitude is limited
by the geometry of the
aeroplane (i.e., tail contact
with the runway), 108% of
V MU in the all-enginesoperating
condition and 104%
of V MU determined at the
thrust-to-weight ratio
corresponding to the oneengine-inoperative
condition.
(See AMC 25.107(e)(1)(iv).)
(2) For any given set of conditions (such
as weight, configuration, and temperature), a
single value of V R , obtained in accordance with
this paragraph, must be used to show compliance
with both the one-engine-inoperative and the allengines-operating
take-off provisions.
(3) It must be shown that the one-engineinoperative
take-off distance, using a rotation
speed of 9.3 km/h (5 knots) less than V R
established in accordance with sub-paragraphs
(e)(1) and (2) of this paragraph, does not exceed
the corresponding one-engine-inoperative take-off
distance using the established V R . The take-off
distances must be determined in accordance with
CS 25.113(a)(1). (See AMC 25.107(e)(3).)
(4) Reasonably expected variations in
service from the established take-off procedures
for the operation of the aeroplane (such as overrotation
of the aeroplane and out-of-trim
conditions) may not result in unsafe flight
characteristics or in marked increases in the
scheduled take-off distances established in
accordance with CS 25.113(a). (See AMC No. 1
to CS25.107 (e) (4) and AMC No. 2 to CS25.107
(e) (4).)
(f) V LOF is the calibrated airspeed at which the
aeroplane first becomes airborne.
(g) V FTO , in terms of calibrated airspeed, must
be selected by the applicant to provide at least the
gradient of climb required by CS 25.121(c), but may
not less less than –
(1) 1.18 V SR ; and
(2) A speed that provides the
manoeuvring capability specified in CS25.143(g).
CS 25.109
Accelerate-stop distance
(a) (See AMC 25.109(a) and (b).) The
accelerate-stop distance on a dry runway is the
greater of the following distances:
–
–
(1) The sum of the distances necessary to
(i) Accelerate the aeroplane from a
standing start with all engines operating to
V EF for take-off from a dry runway;
(ii) Allow the aeroplane to
accelerate from V EF to the highest speed
reached during the rejected take-off,
assuming the critical engine fails at V EF and
the pilot takes the first action to reject the
take-off at the V 1 for take-off from a dry
runway; and
(iii) Come to a full stop on a dry
runway from the speed reached as
prescribed in sub-paragraph (a)(1)(ii) of this
paragraph; plus
(iv) A distance equivalent to
2 seconds at the V 1 for take-off from a dry
runway.
(2) The sum of the distances necessary to
(i) Accelerate the aeroplane from a
standing start with all engines operating to
the highest speed reached during the
rejected take-off, assuming the pilot takes
the first action to reject the take-off at the
V 1 for take-off from a dry runway; and
(ii) With all engines still operating,
come to a full stop on a dry runway from
the speed reached as prescribed in subparagraph
(a)(2)(i) of this paragraph; plus
(iii) A distance equivalent to
2 seconds at the V 1 for take-off from a dry
runway.
(b) (See AMC 25.109(a) and (b).) The
accelerate-stop distance on a wet runway is the
greater of the following distances:
(1) The accelerate-stop distance on a dry
runway determined in accordance with subparagraph
(a) of this paragraph; or
(2) The accelerate-stop distance
determined in accordance with sub-paragraph (a)
of this paragraph, except that the runway is wet
1-B-5