The ICAO regulation Annex 14, Appendix 6-1 prescribes the use of flashing white medium-intensity Aircraft Warning Lights (MIOL-A) both in day mode (20,000cd) and in night mode (2.000cd).
Depending on the height of the structure, the standard requests the use of one or more levels, which are intended to give an exact definition of the object and its size: for structures with a height of up to 45 meters, only one level of Aircraft Warning Lights have to be installed at the top of the structure, while for structures with a height of up to 150 meters two levels of lights are required: one at the top and one at half height of the structure.
If the structure exceeds 150 meters in height, it is possible to continue to use medium intensity Type A beacons placed at regular intervals (as indicated in the table), but the structure must also be marked (painted with white / red horizontal stripes). As alternative, and to avoid the marking of the structure, ICAO rule allows to use only Aircraft Warning Lights; in this case -as indicated in Appendix 6-6; 6-7; 6-8- high intensity beacons (200.000cd in day mode) must be used.
Finally, if an aeronautical study or the civil aviation body under which the control of the structure in question falls, decide the use of other lights or other configurations, the prescriptions must be respected by way of derogation from the ICAO standard Annex 14.