664 

14 CFR Ch. I (1–1–19 Edition) 

§ 29.1389 

(c) Dihedral angle 

R 

(right) is formed 

by two intersecting vertical planes, the 
first parallel to the longitudinal axis of 
the rotorcraft, and the other at 110 de-
grees to the right of the first, as viewed 
when looking forward along the longi-
tudinal axis. 

(d) Dihedral angle 

A 

(aft) is formed 

by two intersecting vertical planes 
making angles of 70 degrees to the 
right and to the left, respectively, to a 
vertical plane passing through the lon-
gitudinal axis, as viewed when looking 
aft along the longitudinal axis. 

(e) If the rear position light, when 

mounted as far aft as practicable in ac-
cordance with § 29.1385(c), cannot show 
unbroken light within dihedral angle A 
(as defined in paragraph (d) of this sec-
tion), a solid angle or angles of ob-
structed visibility totaling not more 
than 0.04 steradians is allowable within 
that dihedral angle, if such solid angle 
is within a cone whose apex is at the 
rear position light and whose elements 
make an angle of 30

° 

with a vertical 

line passing through the rear position 
light. 

(49 U.S.C. 1655(c)) 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 29–9, 36 FR 21279, Nov. 5, 
1971] 

§ 29.1389

Position light distribution 

and intensities. 

(a) 

General. 

The intensities prescribed 

in this section must be provided by new 
equipment with light covers and color 
filters in place. Intensities must be de-
termined with the light source oper-
ating at a steady value equal to the av-
erage luminous output of the source at 
the normal operating voltage of the 
rotorcraft. The light distribution and 
intensity of each position light must 
meet the requirements of paragraph (b) 
of this section. 

(b) 

Forward and rear position lights. 

The light distribution and intensities 
of forward and rear position lights 
must be expressed in terms of min-
imum intensities in the horizontal 
plane, minimum intensities in any 
vertical plane, and maximum inten-
sities in overlapping beams, within di-
hedral angles, 

L, R, 

and 

A, 

and must 

meet the following requirements: 

(1) 

Intensities in the horizontal plane. 

Each intensity in the horizontal plane 

(the plane containing the longitudinal 
axis of the rotorcraft and perpendicular 
to the plane of symmetry of the rotor-
craft), must equal or exceed the values 
in § 29.1391. 

(2) 

Intensities in any vertical plane. 

Each intensity in any vertical plane 
(the plane perpendicular to the hori-
zontal plane) must equal or exceed the 
appropriate value in § 29.1393 where 

I 

is 

the minimum intensity prescribed in 
§ 29.1391 for the corresponding angles in 
the horizontal plane. 

(3) 

Intensities in overlaps between adja-

cent signals. 

No intensity in any over-

lap between adjacent signals may ex-
ceed the values in § 29.1395, except that 
higher intensities in overlaps may be 
used with the use of main beam inten-
sities substantially greater than the 
minima specified in §§ 29.1391 and 
29.1393 if the overlap intensities in rela-
tion to the main beam intensities do 
not adversely affect signal clarity. 

§ 29.1391

Minimum intensities in the 

horizontal plane of forward and 
rear position lights. 

Each position light intensity must 

equal or exceed the applicable values in 
the following table: 

Dihedral angle (light in-

cluded) 

Angle from right or left 

of longitudinal axis, 

measured from dead 

ahead 

Intensity 

(candles) 

L 

and 

R 

(forward red 

and green).

0

° 

to 10

°

.....................

10

° 

to 20

°

...................

20

° 

to 110

°

.................

40 
30 

5 

A 

(rear white) ..............

110

° 

to 180

°

...............

20 

§ 29.1393

Minimum intensities in any 

vertical plane of forward and rear 
position lights. 

Each position light intensity must 

equal or exceed the applicable values in 
the following table: 

Angle above or below the horizontal plane 

Intensity, 

I 

0

°

.........................................................................

1.00 

0

° 

to 5

°

................................................................

.90 

5

° 

to 10

°

..............................................................

.80 

10

° 

to 15

°

............................................................

.70 

15

° 

to 20

°

............................................................

.50 

20

° 

to 30

°

............................................................

.30 

30

° 

to 40

°

............................................................

.10 

40

° 

to 90

°

............................................................

.05 

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