Tall structures and buildings either temporary or permanent, which have the potential to endanger aviation in navigable airspace or has the potential to interfere with the operation of navigation, should be lighted.
- The number of light levels recommended depends on the height of the structure;
- The number and arrangement of light units at each level should be placed so the lighting is visible from every angle in azimuth;
- Lights are applied to display the general definition of an object or a group of buildings;
- Width and length of buildings determine the number of lights installed at the top and at each light level.
Low intensity lights should be used for structure with H ≤ 45 m during night time, if those are considered inadequate, than medium - high intensity lights should be used.
Medium intensity lights type A,B or C should be used to lit extensive object (group of buildings or tree) or structure with 45 m < H ≤ 150 m.
Note: Medium intensity lights, type A and C should be used alone, whereas medium intensity lights, Type B should be used either alone or in combination with LIOL-B.
High intensity type A, should be used to indicate the presence of an object if its H > 150 m and an aeronautical study indicates such lights to be essential for the recognition of the object by day.
Possible configurations according to ICAO ANNEX 14, 7th edition 2016 vol1, appendix 6 – location of lights on obstacles.