84.15—Intensity of lights.

(a) The minimum luminous intensity of lights shall be calculated by using the formula:

Code of Federal Regulations

I=3.43×106×T×D2×K−D

where I is luminous intensity in candelas under service conditions,

T is threshold factor 2×10−7 lux,

D is range of visibility (luminous range) of the light in nautical miles,

K is atmospheric transmissivity. For prescribed lights the value of K shall be 0.8, corresponding to a meteorological visibility of approximately 13 nautical miles.

(b) A selection of figures derived from the formula is given in Table 84.15(b):

Table 84.15(b)

Range of visibility (luminous range) of light in nautical miles D	Minimum luminous intensity of light in candelas for K=0.8 I
1	0.9
2	4.3
3	12
4	27
5	52
6	94

CFR

84.15—Intensity of lights.

Code of Federal Regulations