353
Federal Aviation Administration, DOT
§ 25.1397
the minimum intensity prescribed in
§ 25.1391 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 given in § 25.1395, except
that higher intensities in overlaps may
be used with main beam intensities
substantially greater than the minima
specified in §§ 25.1391 and 25.1393 if the
overlap intensities in relation to the
main beam intensities do not adversely
affect signal clarity. When the peak in-
tensity of the forward position lights is
more than 100 candles, the maximum
overlap intensities between them may
exceed the values given in § 25.1395 if
the overlap intensity in Area A is not
more than 10 percent of peak position
light intensity and the overlap inten-
sity in Area B is not greater than 2.5
percent of peak position light inten-
sity.
§ 25.1391
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 longitu-
dinal axis, meas-
ured 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
§ 25.1393
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, l
0
°
.........................................................................
1.00
0
°
to 5
°
................................................................
0.90
5
°
to 10
°
..............................................................
0.80
10
°
to 15
°
............................................................
0.70
15
°
to 20
°
............................................................
0.50
20
°
to 30
°
............................................................
0.30
30
°
to 40
°
............................................................
0.10
40
°
to 90
°
............................................................
0.05
§ 25.1395
Maximum intensities in over-
lapping beams of forward and rear
position lights.
No position light intensity may ex-
ceed the applicable values in the fol-
lowing table, except as provided in
§ 25.1389(b)(3).
Overlaps
Maximum intensity
Area A
(candles)
Area B
(candles)
Green in dihedral angle L .............
10 1
Red in dihedral angle R ................
10 1
Green in dihedral angle A .............
5 1
Red in dihedral angle A ................
5 1
Rear white in dihedral angle L ......
5 1
Rear white in dihedral angle R .....
5 1
Where—
(a) Area A includes all directions in
the adjacent dihedral angle that pass
through the light source and intersect
the common boundary plane at more
than 10 degrees but less than 20 de-
grees; and
(b) Area B includes all directions in
the adjacent dihedral angle that pass
through the light source and intersect
the common boundary plane at more
than 20 degrees.
§ 25.1397
Color specifications.
Each position light color must have
the applicable International Commis-
sion on Illumination chromaticity co-
ordinates as follows:
(a)
Aviation red—
y is not greater than 0.335; and
z is not greater than 0.002.
(b)
Aviation green—
x is not greater than 0.440
¥
0.320
y ;
x is not greater than y
¥
0.170; and
y is not less than 0.390
¥
0.170
x.
(c)
Aviation white—
x is not less than 0.300 and not greater than
0.540;
y is not less than x
¥
0.040; or
y
0
¥
0.010, which-
ever is the smaller; and
y is not greater than x + 0.020 nor
0.636
¥
0.400
x;
Where
y
0
is the
y coordinate of the Planckian
radiator for the value of
x considered.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–27, 36 FR 12972, July 10,
1971]
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