212 

14 CFR Ch. I (1–1–19 Edition) 

§ 25.109 

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 
(a) of this section, except that the run-
way is wet and the corresponding wet 
runway values of V

EF

and V

1

are used. 

In determining the wet runway accel-
erate-stop distance, the stopping force 
from the wheel brakes may never ex-
ceed: 

(i) The wheel brakes stopping force 

determined in meeting the require-
ments of § 25.101(i) and paragraph (a) of 
this section; and 

(ii) The force resulting from the wet 

runway braking coefficient of friction 
determined in accordance with para-
graphs (c) or (d) of this section, as ap-
plicable, taking into account the dis-
tribution of the normal load between 
braked and unbraked wheels at the 
most adverse center-of-gravity position 
approved for takeoff. 

(c) The wet runway braking coeffi-

cient of friction for a smooth wet run-
way is defined as a curve of friction co-
efficient versus ground speed and must 
be computed as follows: 

(1) The maximum tire-to-ground wet 

runway braking coefficient of friction 
is defined as: 

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