Note for Installers: The required type of obstruction light is often already specified in the bid or contract documents.

• The height of the structure to be illuminated and the operating hours (day/night/twilight) are decisive factors in selecting the correct type of obstruction light.

• Other factors include the location, environmental conditions, existing air traffic, and other light sources installed in the vicinity.

• Depending on the operating hours, the installation of an automatic brightness control system may be necessary.

• Depending on the application, a dual obstruction light may be required if increased reliability is needed.

• Hazard lights must be installed only when obstacle clearance is particularly compromised; however, for structures over 100 m in height above ground or water, they must always be installed if, for technical reasons, the highest point cannot be illuminated and the unlit portion exceeds the hazard light by more than 15 m.

• Daytime lights can be used for daytime identification instead of colored markings. This usually significantly reduces installation and maintenance costs, allowing a daytime beacon system to be operated cost-effectively.

• For installations that are difficult to access for maintenance purposes, it may be advisable to choose a dual-obstacle beacon with automatic switching. The use of a controlled and monitored system is advisable to receive feedback on the operational status.

• For lights with a long lamp life (e.g., LEDs), a spare lamp is not required if the operating time is recorded and the lamp is replaced once the point at which the probability of failure reaches 5% is reached.

  High-intensity obstruction beacons should be continuously monitored by an automatic control system or visually inspected once every 24 hours.

Obstruction lighting must be clearly visible from all directions to ensure aviation safety at all times. Obstruction lights should be installed as close as possible to the highest point of a structure so that the obstacle can be identified clearly and at an early stage from the air.

For large objects or groups of closely spaced objects, obstruction lights should be positioned in such a way that the contours of the object are clearly recognizable. Highlighting straight lines and corners can help ensure clear identification. Synchronization of flashing obstruction lights, for example via GPS modules, can provide additional support.

The height of an object determines the number of required obstruction lighting levels. The distance between two levels must not exceed 45 m (N = object height / maximum level spacing). If, for technical reasons, the obstruction light cannot be installed at the highest point, the unlit section may extend no more than 15 m above the light. On chimneys, the uppermost obstruction lights should be installed 1.5 to 3 m below the top to prevent interference from smoke – while ensuring that the obstruction lighting remains visible from all directions.

For a group of buildings or trees, medium-intensity obstruction lights should be used.

The number of high-intensity obstruction lights per lighting level depends on the diameter of the object to be marked. The aim is to ensure unobstructed visibility of the obstruction lighting from all directions. The following table provides guidelines for the number of obstruction lights required per level.