455 

Federal Aviation Administration, DOT 

§ 25.812 

each passenger emergency exit mark-
ing sign required by § 25.811(d)(2) must 
have red letters at least 1

1

⁄

2

inches high 

on an illuminated white background, 
and must have an area of at least 21 
square inches excluding the letters. 
The lighted background-to-letter con-
trast must be at least 10:1. The letter 
height to stroke-width ratio may not 
be more than 7:1 nor less than 6:1. 
These signs must be internally elec-
trically illuminated with a background 
brightness of at least 25 foot-lamberts 
and a high-to-low background contrast 
no greater than 3:1. 

(ii) Each passenger emergency exit 

sign required by § 25.811(d)(3) must have 
red letters at least 1

1

⁄

2

inches high on a 

white background having an area of at 
least 21 square inches excluding the 
letters. These signs must be internally 
electrically illuminated or self-illumi-
nated by other than electrical means 
and must have an initial brightness of 
at least 400 microlamberts. The colors 
may be reversed in the case of a sign 
that is self-illuminated by other than 
electrical means. 

(2) For airplanes that have a pas-

senger seating configuration, excluding 
pilot seats, of nine seats or less, that 
are required by § 25.811(d)(1), (2), and (3) 
must have red letters at least 1 inch 
high on a white background at least 2 
inches high. These signs may be inter-
nally electrically illuminated, or self- 
illuminated by other than electrical 
means, with an initial brightness of at 
least 160 microlamberts. The colors 
may be reversed in the case of a sign 
that is self-illuminated by other than 
electrical means. 

(c) General illumination in the pas-

senger cabin must be provided so that 
when measured along the centerline of 
main passenger aisle(s), and cross 
aisle(s) between main aisles, at seat 
arm-rest height and at 40-inch inter-
vals, the average illumination is not 
less than 0.05 foot-candle and the illu-
mination at each 40-inch interval is not 
less than 0.01 foot-candle. A main pas-
senger aisle(s) is considered to extend 
along the fuselage from the most for-
ward passenger emergency exit or 
cabin occupant seat, whichever is far-
ther forward, to the most rearward pas-
senger emergency exit or cabin occu-
pant seat, whichever is farther aft. 

(d) The floor of the passageway lead-

ing to each floor-level passenger emer-
gency exit, between the main aisles 
and the exit openings, must be pro-
vided with illumination that is not less 
than 0.02 foot-candle measured along a 
line that is within 6 inches of and par-
allel to the floor and is centered on the 
passenger evacuation path. 

(e) Floor proximity emergency es-

cape path marking must provide emer-
gency evacuation guidance for pas-
sengers when all sources of illumina-
tion more than 4 feet above the cabin 
aisle floor are totally obscured. In the 
dark of the night, the floor proximity 
emergency escape path marking must 
enable each passenger to— 

(1) After leaving the passenger seat, 

visually identify the emergency escape 
path along the cabin aisle floor to the 
first exits or pair of exits forward and 
aft of the seat; and 

(2) Readily identify each exit from 

the emergency escape path by ref-
erence only to markings and visual fea-
tures not more than 4 feet above the 
cabin floor. 

(f) Except for subsystems provided in 

accordance with paragraph (h) of this 
section that serve no more than one as-
sist means, are independent of the air-
plane’s main emergency lighting sys-
tem, and are automatically activated 
when the assist means is erected, the 
emergency lighting system must be de-
signed as follows. 

(1) The lights must be operable 

manually from the flight crew station 
and from a point in the passenger com-
partment that is readily accessible to a 
normal flight attendant seat. 

(2) There must be a flight crew warn-

ing light which illuminates when power 
is on in the airplane and the emergency 
lighting control device is not armed. 

(3) The cockpit control device must 

have an ‘‘on,’’ ‘‘off,’’ and ‘‘armed’’ posi-
tion so that when armed in the cockpit 
or turned on at either the cockpit or 
flight attendant station the lights will 
either light or remain lighted upon 
interruption (except an interruption 
caused by a transverse vertical separa-
tion of the fuselage during crash land-
ing) of the airplane’s normal electric 
power. There must be a means to safe-
guard against inadvertent operation of 

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