Aircraft Detection Lighting System (ADLS) for new wind turbines

ADLS: an end to pointless flashing

Aircraft Detection Lighting Systems ensure that the lights of wind turbines only flash when an aircraft is actually in the vicinity. The systems detect the position and route of aircraft. While earlier ADL systems were based on radar technology, transponder-based detection has now become established. In this case, aircraft emit signals that are detected by the turbines.

There are two types of transponder-based ADLS:

Multilateration: several receivers determine the position of an aircraft based on the time differences in receiving the signal. This method is particularly precise but requires a complex infrastructure.

Single receiver approach: a single receiver estimates the position based on the signal strength and direction. This variant is simpler and cheaper but less accurate.

Modern ADL systems such as the light:guard system can use both approaches, depending on the location. In densely populated areas, multilateration ensures more precise detection and longer phases without blinking. In isolated locations, a single receiver is often sufficient.

History of ADLS in Germany

The legal requirement for ADLS equipment was already established in the Renewable Energy Sources Act (EEG) in 2019. It was originally supposed to apply from mid-2020, but was postponed several times – most recently to January 1, 2025. The reasons for this were technical challenges, certification problems and pandemic-related bottlenecks. However, providers and operators are now well positioned, and many wind farms have already been able to activate their ADLS.

ADLS for new wind turbines

Some new wind turbines and farms also already have an active or at least installed ADLS. This must also be the case from the new year at the latest. New plants must be equipped with active ADLS from the moment they are put into operation, without exception. If this requirement is not met, there is a risk of severe penalties: 10 euros per kilowatt of installed capacity per month will be incurred – for a 3.5-megawatt plant, this adds up to 35,000 euros. Operators and project planners must therefore plan for ADLS at an early stage.

Thanks to optimized processes, ADLS systems can now be installed more efficiently. Providers such as Light:Guard already cover large parts of Germany, so the systems are often ready for use within a few weeks.

Outlook

It is still unclear whether ADLS can be considered a success, as it is too early to assess its acceptance by the population. However, initial data show promising results: in areas with little air traffic, the wind turbines remain almost completely dark. 

The technology is also attracting interest internationally. In Austria, ADLS is being used voluntarily, while in the Netherlands it is already established. In the coming years, on-demand nighttime aircraft marking is likely to become widespread worldwide – a win for residents and the night sky.