Obstacle lighting in Germany – comprehensive guide

What is obstacle lighting?

Lighting refers to largely stationary light or radio signals used for navigation in aviation. There are different terms such as runway lighting, approach lighting, obstacle lighting, rotating lights and code lights. Obstacle lighting is a system of light signals that serves to make aviation obstacles visible to pilots and thus prevent collisions.

It consists of one or more light sources mounted at regular intervals on the obstacle and emitting a bright, flashing light. The lights are usually of a specific colour, such as red or white, and must comply with certain standards and regulations.

What is an obstacle light?

Obstacle lights and obstacle lights (ES) are permanently red omnidirectional or partial lights in accordance with Annex 1 of the AVV. In this AVV, obstacle lights and obstacle lights (ES) are treated as equivalent and are referred to as obstacle lights in the following.

Technical specifications:

Obstruction lights and obstacle lights (ES) are red omnidirectional fixed lights or partial lights with a light intensity of at least 10 cd in the vertical beam range from -2° to + 10°.
Low Intensity Obstacle Light, Type A (10 cd red, permanently lit) as night lighting.

What is a danger light?

Danger lights are red flashing omnidirectional lights and differ fundamentally from obstacle lights:

The danger light is a red flashing omnidirectional light with a luminous intensity of 2,000 cd (medium-intensity light type B according to ICAO Annex 14)
Obstacles that could pose a particular hazard to aviation safety due to their location or extent must be equipped with hazard lights (red flashing light, 20 to 60 times per minute with a luminous intensity of at least 2000 cd) instead of or in addition to obstacle lights.

What is an example of an obstacle?

An aviation obstacle is an object that, due to its height, constitutes an obstacle to air traffic. In addition to structures, obstacles can also be vehicles, people, natural vegetation such as trees, etc., or even aircraft, provided they are located at the aerodrome itself or in the immediate vicinity of the aerodrome. Examples include overhead power lines and high-rise buildings, especially near airfields, as well as telecommunications towers, tall chimneys, cranes and wind turbines.

Further specific examples:

Wind turbines: Wind turbines are generally treated in Germany in accordance with the guidelines for general aviation obstacles and must therefore be marked if they exceed a total height of 100 m.
Television towers: To ensure flight safety in various weather conditions, the television tower has several lighting systems. Obstacle lights are installed along the shaft at 91, 136 and 181 metres, and on the antenna mast at 267, 303 and 329 metres. These lights are permanently red.

When do buildings have red flashing lights and when do they have permanently lit lights?

The decision between flashing and permanently lit lights depends on the type and height of the obstacle:

Permanently lit red lights (obstacle lights):

Obstacle lights and obstacle lights (ES) are permanently red omnidirectional or partial lights
Used on most standard aviation obstacles

Red flashing lights (danger lights):

Hazard lights must only be installed if obstacle clearance is particularly impaired, but must always be installed on structures over 100 metres above ground or water if the highest point cannot be lit for technical reasons and the unlit part exceeds the hazard light by more than 15 metres.

Combination of both systems:

Above the tower ball at 230 metres and at the top of the antenna mast, there are additional flashing danger lights with a three-second cycle. The flashing lights automatically switch to white during daylight and red during darkness.

What light colours are used for obstacle lighting?

The light colour for obstacle lights, obstacle lights ES and hazard lights is red in accordance with ICAO Annex 14 Volume 1 Appendix 1 Figure 1.1 Colours for aeronautical ground lights.

Red light:

Standard for night-time identification
The colour red is chosen because of its high visibility in poor lighting conditions.

White light:

In some cases, a combination of different types of obstacle lighting is used to ensure optimum visibility. For example, a structure may be equipped with a high-intensity white light for visibility during the day and a medium-intensity red light for visibility at night.

Infrared:

Infrared lights in accordance with section 3.6 may be required by the competent national aviation authority in addition to night-time marking, depending on the obstacle situation.
For reasons of reliability, LED light sources are used almost exclusively, but these are often not detected by night vision devices due to their lack of infrared components. Some countries require the use of additional infrared lighting.

Why do lights flash on tall buildings?

The flashing lights serve several important purposes:

Attention: Flashing lights are more noticeable than steady lights and attract the attention of pilots more effectively.
Distinction: Hazard lights are red flashing omnidirectional lights – they signal a particular hazard.
International standards: According to the International Civil Aviation Organisation (ICAO) obstacle light requirements, all structures exceeding 45 metres above ground level (AGL) must be appropriately marked with aviation warning lights

Why is there a red light on the tower?

Red lights on towers have several important functions:

Safety standard: Aviation obstacles near airfields have been marked with warning paint and red lights as obstacle lights (OBSL = Obstruction Lights).
Optimal visibility: Red FAA obstruction lights are a type of aviation obstruction light that emits a steady or flashing red light in accordance with Federal Aviation Administration (FAA) standards. They are primarily used to mark tall structures to warn pilots of potential hazards. The red colour is chosen for its high visibility in poor lighting conditions.

What distance must aircraft maintain from aviation obstacles?

The distances between aircraft are clearly regulated, but specific distances from obstacles are determined by various factors:

Minimum flight altitude above obstacles:

Over populated areas and gatherings of people, a flight altitude of 1,000 ft above the highest obstacle with a horizontal distance of 2,000 ft
Over other areas, a flight altitude of 500 ft above ground level. Over water and sparsely populated areas, even lower, but no approach to people, vehicles or structures below 500 ft.

Aircraft-to-aircraft distances:

According to BDL specifications, the minimum distance near airports is 3 nautical miles (NM), which is 5.56 kilometres (km). During landing approach, this may be reduced to 2.5 NM (4.63 kilometres). And in the air, it is 5 NM (9.26 kilometres).
The vertical separation from another aircraft must be 1000 feet, i.e. at least 304.8 metres.

What are the three types of obstacles?

According to German administrative regulations and ICAO standards, obstacles can be divided into different categories:

1. According to the intensity of the lighting:

Type A High Intensity Flashing White + Type B Medium Intensity Flashing Red
Low Intensity Obstacle Light, Type A (10 cd red, permanently lit) as night lighting

2. By design/function:

Fixed obstacles: Examples include overhead power lines and high-rise buildings, especially near airports, as well as telecommunications towers, tall chimneys, cranes and wind turbines.
Temporary obstacles: Temporary obstacles must be marked in solid white, yellow, red or orange, or alternating red and white or orange and white, with a bandwidth of not less than one metre.
Cable-shaped obstacles: Obstacle lights for marking cable-shaped obstacles are not technically specified, but may be used.

3. By height (German regulations):

Outside the building protection areas (§ 12 and § 17 LuftVG), structures with a height of more than 100 m above ground level, or more than 150 m in densely populated areas and cities, must be marked in Germany.

What happens if an obstacle light fails?

The failure of an obstacle lighting system triggers a regulated reporting process:

Immediate measures:

If the light fails, the operator must be notified immediately. Malfunctions of the lights that cannot be rectified immediately must be reported to the responsible NOTAM centre without delay.

Rectification deadlines:

The failure of the marking must be rectified as quickly as possible. Once the fault has been rectified, the NOTAM centre must be notified immediately. If rectification is not possible within two weeks, the NOTAM centre and the responsible state aviation authority must be informed again.

Safety systems:

In the event of a radar system failure, the night-time lighting shall be switched back to continuous operation.
A backup power supply plan must be submitted to ensure a supply duration of at least 16 hours in the event of a failure of the primary electrical power supply.

How can I see which obstacle lights are out?

There are several systems for monitoring and providing information about failed obstacle lights:

Automatic monitoring systems:

Monitoring can also be carried out remotely to quickly detect and rectify any faults or failures.
The trouble-free operation of obstacle lighting systems must be ensured in accordance with the applicable regulations, which is why control and monitoring systems are indispensable.

GSM monitoring:

This cost-effective monitoring solution allows the user to monitor and control the operating status of each light with a GSM module. The system can be configured to send (alarm) SMS messages to predefined mobile phone numbers in the event of certain predefined events.

NOTAM system:

Fire malfunctions that cannot be rectified immediately must be reported to the responsible NOTAM centre without delay. NOTAMs (Notices to Airmen) inform pilots about failed lighting.

Monitoring obligations:

High-performance obstacle lights should be monitored continuously by means of an automatic control system or visually checked once every 24 hours.
All 5-nautical-mile lights in use must be equipped with automatic monitoring to detect failure.

Sources

General Administrative Regulation on the Marking of Obstacles to Air Navigation of 24 April 2020 (BAnz AT 30.04.2020 B4)
ICAO Annex 14 - Aerodromes, Volume I - Aerodrome Design and Operations
Federal Association of the German Aviation Industry (BDL)
Wikipedia article on aviation obstacles and lighting
Manufacturer information from various suppliers of obstacle lighting systems