A first distinction made in regulations is related to lamp types. According to ICAO, standard light units are distinguished by a set of parameters: light intensity, beam pattern, light color, flash rates.
ICAO divides aviation obstruction lamps into three main groups:
Low intensity obstruction lights: these lights should be used where the object height above the surrounding ground is lower than 45 m.
Medium intensity obstruction lights: should be used where the object height above the level of the surrounding ground is higher than 45 m.
High intensity obstruction lights: these lights should be used to indicate the presence of an object if its height above the level of the surrounding ground exceeds 150 m.
In detail, the regulation describes different lamp types within the above three groups.
Low intensity obstacle lights, on fixed objects, are fixed-red lights divided in two types:
Type A: With minimum intensity of 10 candelas.
Type B: With minimum intensity of 32 candelas.
There are two other types of low intensity obstacle lights, Type C and D used on security vehicles and other vehicles.
Medium intensity obstacle lights are divided into three types:
Type A: White color flashing lights with intensity of 20.000 candelas during daytime, 2.000 during nighttime
Type B: Red color flashing lights with minimum intensity of 2.000 candelas.
Type C: Red color fixed lights with intensity of 2.000 candelas.
High intensity lights are divide in two types:
Type A: White color flashing lights, with minimum intensity of 200.000 candelas during daytime, 20.000 candelas during twilight and 2.000 candelas during nighttime.
Type B: White color flashing lights, with minimum intensity of 100.000 candelas during daytime, 20.000 candelas during twilight and 2.000 candelas during nighttime.
Moreover, regulations provide details for every characteristic of each type of obstacle lights, defining vertical beam spread, intensity at given elevation angles, flashing intervals and flashing duty cycles.