Federal Aviation Administration, DOT

Section 25.777

(3) The vision system must provide a
means to allow the pilot using the display to immediately deactivate and reactivate 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 specified in paragraph (a)(1) of this section
or the pilot compartment from meeting the provisions of paragraph (a)(2) of
this section.

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[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]

Section 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 structures 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 VC, at sea level, selected
under Section 25.335(a).
(c) Unless it can be shown by analysis
or tests that the probability of occurrence of a critical windshield fragmentation 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 altitude operation, including the effects
of continuous and cyclic pressurization
loadings, the inherent characteristics

of the material used, and the effects of
temperatures and temperature differentials. The windshield and window
panels must be capable of withstanding
the maximum cabin pressure differential loads combined with critical aerodynamic pressure and temperature effects after any single failure in the installation or associated systems. It
may be assumed that, after a single
failure that is obvious to the flight
crew (established under Section 25.1523), the
cabin pressure differential is reduced
from the maximum, in accordance with
appropriate operating limitations, to
allow continued safe flight of the airplane 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, assuming 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]

Section 25.777 Cockpit controls.
(a) Each cockpit control must be located to provide convenient operation
and to prevent confusion and inadvertent operation.
(b) The direction of movement of
cockpit controls must meet the requirements of Section 25.779. Wherever practicable, 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 position, 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 unrestricted movement of each control
without interference from the cockpit
structure or the clothing of the minimum flight crew (established under
Section 25.1523) when any member of this
flight crew, from 5-2- to 6-3- in height,
is seated with the seat belt and shoulder harness (if provided) fastened.
(d) Identical powerplant controls for
each engine must be located to prevent

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