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

I  =  3,43  x  106  x  T  x  D2  x  K-D

where: I    is luminous intensity in candelas under service conditions

T    is threshold factor  2 x 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 K shall be 0,8, corresponding to a meterorological visibility of approximately 13 nautical miles.

(b)        A selection of figures derived from the formula is given in the following table: