6.1.1. Helihoist Lighting Guidance
- The UK requirements as described in CAA (2021a) and listed below will be adopted for the Array, should heli-hoisting be undertaken as part of normal operations:
- low intensity green lights to be fitted to the wind turbine nacelle to indicate the status of the wind turbine for hoisting operations to helicopter pilots. The status shall be indicated as follows:
– steady green light indicates that the wind turbine blades and nacelle are secure and it is safe to operate;
– flashing green signal indicates that the wind turbine is in a state of preparation to accept hoist operations, or if displayed during hoist operations, that parameters are moving out of limits; and.
– extinguished light indicates that it is not safe to conduct helicopter hoist operations.
6.1.2. Aviation Warning Lights
- In the UK, the International Civil Aviation Organization (ICAO) requirements for lighting wind turbines are implemented through:
- Air Navigation Order 2016;
- CAP 393: Regulations made under powers in the Civil Aviation Act 1982 and the Air Navigation Order 2016 (CAA, 2021b); and
- CAP 764: Policy and Guidelines on Wind Turbines (CAA, 2016.
- Red, medium intensity aviation warning lights (2,000 candela (cd)), with the 2,000 cd light conforming to ICAO specification will be fitted. Aviation lighting will be subject to reduction in lighting intensity, to a minimum of 200 cd, when the visibility in all directions from every wind turbine is more than 5 km, as identified by visibility meters on selected periphery wind turbines.
- Aviation lighting to be located on top (or as close as possible) of the nacelle for 360 degree visibility and on all peripheral wind turbines. Aviation warning lights would flash simultaneously synchronised Morse ‘W’ and be able to be switched on and off by means of twilight switches.
- Article 223 of Air Navigation Order 2016 also requires that “the angle of the plane of the beam of peak intensity emitted by the light must be elevated to between 3-4° degrees above the horizontal plane”, but that 20-45% of the peak intensity is to be visible at the horizontal plane and not more than 10% of the peak intensity is visible at 1.5 degrees or more below the horizontal plane. This focusses the 2,000cd lighting in the horizontal plane between 3-4° degrees above horizontal and allows for a reduced intensity of the light at and below the horizontal plane.
- Aviation lighting will be remotely controlled by the SCADA system and will be visible at night and turned off during the day.
- SAR lighting of wind turbines and OSPs will be 200 cd steady red aviation hazard lights, individually switchable. These low intensity lights will be turned off by default, during day and night. The SAR lights will be turned on only if required for SAR operations or at the MCA’s request.
6.2.1. Blade Hover Reference Marking
- Wind turbine blades need to be marked to provide a SAR pilot with a hover reference point when hovering over a nacelle. There is a requirement for three markings on the blade, on both faces of the blade at 10 m, 20 m and 30 m internal (starting from the hub end of the blade and placed near the trailing edge of the blades).
- These marks (preferably dots) should be painted in a contrasting shade to the blades overall colour, red (RA 3020) being considered the most suitable option. The diameter of these marks should be at least 600 mm (MCA, 2024).
6.2.2. Blade Tips
- Wind turbine blade tips should also be marked in a contrasting shade to the wind turbines overall colour, red (RAL 3020) being considered the most suitable option. Approximately 2% of the blade length should be coloured (MCA, 2024).
- Where blade tips cannot be painted, an alternative solution will be discussed with the MCA and approval by the MCA sought after before placing them on the blades. Furthermore, all markings must be maintained in operational condition throughout the life of the wind farm (MCA, 2024).
6.2.3. Nacelle and OSP Topside Roof
- Wind turbine identification numbers should also be placed on the nacelle and OSP topside roofs. These identification numbers should be as large as possible but not less than 1.5 m in height and proportionate width. They should also be recognisable from an aircraft flying 500 ft (152 m) above the highest part of the structure (MCA, 2021b).
6.2.4. Helihoist Deck
- The colour of the helideck should be dark green for the safety zone and a contrasting dark grey for the associated access route. The perimeter of the safety zone should be clearly marked with a white painted line 0.3 m wide. The surface of the winching area (a minimum 4 m2 'clear area') should be painted yellow. The railings around the entire winching area, including the helihoist deck, safety zone and associated access route, should be painted in a conspicuous colour, preferably red (CAA, 2021).