279 

Federal Aviation Administration, DOT 

§ 25.777 

(3) The vision system must provide a 

means to allow the pilot using the dis-
play to immediately deactivate and re-
activate the vision system imagery, on 
demand, without removing the pilot’s 
hands from the primary flight controls 
or thrust controls. 

(4) When the vision system is not in 

operation it may not restrict the pilot 
from performing the maneuvers speci-
fied in paragraph (a)(1) of this section 
or the pilot compartment from meet-
ing the provisions of paragraph (a)(2) of 
this section. 

[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; Amdt. 25–140, 79 FR 
65525, Nov. 4, 2014; Docket FAA–2013–0485, 
Amdt. 25–144, 81 FR 90169, Dec. 13, 2016] 

§ 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. 

(b) The direction of movement of 

cockpit controls must meet the re-
quirements of § 25.779. Wherever prac-
ticable, the sense of motion involved in 
the operation of other controls must 
correspond to the sense of the effect of 
the operation upon the airplane or 
upon the part operated. Controls of a 
variable nature using a rotary motion 
must move clockwise from the off posi-
tion, through an increasing range, to 
the full on position. 

(c) The controls must be located and 

arranged, with respect to the pilots’ 
seats, so that there is full and unre-
stricted movement of each control 
without interference from the cockpit 
structure or the clothing of the min-
imum flight crew (established under 
§ 25.1523) when any member of this 
flight crew, from 5

′

2

″ 

to 6

′

3

″ 

in height, 

is seated with the seat belt and shoul-
der harness (if provided) fastened. 

(d) Identical powerplant controls for 

each engine must be located to prevent 

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