439 

Federal Aviation Administration, DOT 

§ 25.777 

(iii) Provides sufficient protection 

from the elements against impairment 
of the pilot’s vision. 

(4) The openable window specified in 

paragraph (b)(3) of this section need 
not be provided if it is shown that an 
area of the transparent surface will re-
main clear sufficient for at least one 
pilot to land the airplane safely in the 
event of— 

(i) Any system failure or combina-

tion of failures which is not extremely 
improbable, in accordance with 
§ 25.1309, under the precipitation condi-
tions specified in paragraph (b)(1) of 
this section. 

(ii) An encounter with severe hail, 

birds, or insects. 

(c) 

Internal windshield and window 

fogging.  The airplane must have a 
means to prevent fogging of the inter-
nal portions of the windshield and win-
dow panels over an area which would 
provide the visibility specified in para-
graph (a) of this section under all in-
ternal and external ambient condi-
tions, including precipitation condi-
tions, in which the airplane is intended 
to be operated. 

(d) Fixed markers or other guides 

must be installed at each pilot station 
to enable the pilots to position them-
selves in their seats for an optimum 
combination of outside visibility and 
instrument scan. If lighted markers or 
guides are used they must comply with 
the requirements specified in § 25.1381. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–23, 35 FR 5676, Apr. 8, 
1970; Amdt. 25–46, 43 FR 50595, Oct. 30, 1978; 
Amdt. 25–72, 55 FR 29778, July 20, 1990; Amdt. 
25–108, 67 FR 70827, Nov. 26, 2002; Amdt. 25– 
121, 72 FR 44669, Aug. 8, 2007; Amdt. 25–136, 77 
FR 1618, Jan. 11, 2012] 

§ 25.775

Windshields and windows. 

(a) Internal panes must be made of 

nonsplintering material. 

(b) Windshield panes directly in front 

of the pilots in the normal conduct of 
their duties, and the supporting struc-
tures for these panes, must withstand, 
without penetration, the impact of a 
four-pound bird when the velocity of 
the airplane (relative to the bird along 
the airplane’s flight path) is equal to 
the value of 

V

C,

at sea level, selected 

under § 25.335(a). 

(c) Unless it can be shown by analysis 

or tests that the probability of occur-
rence of a critical windshield frag-
mentation condition is of a low order, 
the airplane must have a means to 
minimize the danger to the pilots from 
flying windshield fragments due to bird 
impact. This must be shown for each 
transparent pane in the cockpit that— 

(1) Appears in the front view of the 

airplane; 

(2) Is inclined 15 degrees or more to 

the longitudinal axis of the airplane; 
and 

(3) Has any part of the pane located 

where its fragmentation will constitute 
a hazard to the pilots. 

(d) The design of windshields and 

windows in pressurized airplanes must 
be based on factors peculiar to high al-
titude operation, including the effects 
of continuous and cyclic pressurization 
loadings, the inherent characteristics 
of the material used, and the effects of 
temperatures and temperature dif-
ferentials. The windshield and window 
panels must be capable of withstanding 
the maximum cabin pressure differen-
tial loads combined with critical aero-
dynamic pressure and temperature ef-
fects after any single failure in the in-
stallation or associated systems. It 
may be assumed that, after a single 
failure that is obvious to the flight 
crew (established under § 25.1523), the 
cabin pressure differential is reduced 
from the maximum, in accordance with 
appropriate operating limitations, to 
allow continued safe flight of the air-
plane with a cabin pressure altitude of 
not more than 15,000 feet. 

(e) The windshield panels in front of 

the pilots must be arranged so that, as-
suming the loss of vision through any 
one panel, one or more panels remain 
available for use by a pilot seated at a 
pilot station to permit continued safe 
flight and landing. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–23, 35 FR 5676, Apr. 8, 
1970; Amdt. 25–38, 41 FR 55466, Dec. 20, 1976] 

§ 25.777

Cockpit controls. 

(a) Each cockpit control must be lo-

cated to provide convenient operation 
and to prevent confusion and inad-
vertent operation. 

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