What Is an Aircraft Detection Lighting System (ADLS) for Wind Turbines?

In the United Kingdom, CAP 764 is the key guidance document for wind turbines and aviation. The current version is CAP 764 Edition 7 with a version date of 17 December 2025. Edition 7 introduces requirements for aviation detection lighting systems and aligns the guidance with IEC TS 61400-29:2023 on marking and lighting of wind turbines.

The baseline legal framework for obstacle lighting away from licensed aerodromes sits in Article 222 of the Air Navigation Order. CAP 764 explains how that framework applies to wind turbines and how ADLS can be used as an operational route to reduce night-time visual impact while keeping aviation safety and compliance in focus.

CAP 764 also sets a clear boundary. ADLS for wind turbine obstruction lighting is not permitted within the obstacle limitation surfaces of a licensed aerodrome because of late detection risk.

For operators, one point matters in day to day terms. The CAA does not approve or continuously oversee an ADLS system. CAP 764 still requires CAA permission under Article 222 for ADLS operation, and it requires a declaration that minimum requirements are met before the system is used operationally.

CAP 764 treats ADLS as a safety system. It defines fail-safe behaviour and sets minimum performance expectations. The fail-safe philosophy is straightforward. Obstacle lights are on by default and the ADLS switches them off when aircraft are outside the detection volume. If the system fails, the lights remain on.

For active sensor solutions such as radar, CAP 764 gives practical requirements that shape design, commissioning, and ongoing assurance.

• Horizontal surveillance coverage should extend to at least 4 nautical miles from the wind farm perimeter. CAP 764 also recommends a single sensor solution sized around 8 nautical miles, or at least enough to cover 4 nautical miles, whichever is greater.
• Vertical coverage should extend up to at least 600 metres above ground level above the highest part of the turbine or group.
• The system update rate should be once every 2 seconds or higher.
• Radio frequencies used for aircraft detection operation must avoid licence-exempt spectrum and must be individually licensed through Ofcom.
• If aircraft have not triggered the system, a self-test activation is required at least once within a 24 hour interval.
• The system must activate obstacle lighting in time before an aircraft penetrates the defined activation volume, including thresholds described by CAP 764 such as 3 nautical miles horizontally from the perimeter and 1000 feet above the tallest point.

CAP 764 recognises two detection approaches. Active sensing detects aircraft as targets. Passive sensing relies on information transmitted by the aircraft. In parts of UK airspace, aircraft may not be required to carry or operate transponders or ADS-B. CAP 764 therefore notes that passive approaches can require additional mitigation. It references Transponder Mandatory Zones as one possible route, subject to the CAA airspace change process.

CAP 764 also puts operational responsibility where it belongs. Wind farm operators are expected to monitor the serviceability of obstacle lighting. When a lighting outage is expected to exceed 12 hours, CAP 764 advises requesting a NOTAM through the UK AIS NOTAM section.

Most ADLS discussions focus on technology. Operators care about what happens after commissioning. Coverage design, spectrum planning, commissioning evidence, logging, and stable behaviour through maintenance windows and outages. That is where proven experience reduces risk.

Light:Guard comes from Germany, a market where demand-controlled night marking has moved from option to standard practice. Light:Guard positions its ADLS as type-tested and aligned with IEC and ICAO related standards, and it references deployments beyond Germany.

For UK projects under CAP 764 Edition 7, Light:Guard also speaks directly to the UK pathway and the minimum requirements operators need to meet. Light:Guard states that it can offer both radar-based and transponder-based approaches together with its sister company Senture GmbH. That flexibility matters in the UK because the right detection method depends on local aviation context.