1. Introduction

1.1. Purpose

This outline Lighting and Marking Plan (LMP) has been prepared by RPS and Ossian Offshore Wind Farm Limited (Ossian OWFL), a joint venture partnership between SSE Renewables (SSER) Limited, Copenhagen Infrastructure Partners (CIP), and Marubeni Corporation (hereafter referred to as ‘the Applicant’), to support the Array Environmental Impact Assessment (EIA) Report for the Ossian Array (hereafter referred to as ‘the Array’).
The lighting and marking of wind turbines and Offshore Substation Platforms (OSPs) will be finalised in consultation with the Northern Lighthouse Board (NLB), Maritime and Coastguard Agency (MCA), Civil Aviation Authority (CAA) and the Ministry of Defence (MOD). An LMP is likely to be required through the Section 36 Consent and Marine Licence as consent conditions and therefore this LMP will be updated and submitted to Marine Directorate - Licensing and Operations Team (MD-LOT) for approval post consent.
This outline LMP aims to set out the aviation and navigational lighting and marking requirements for the Array.

2. Project Background and Consent Conditions

2.1. Project Background

The Array is located off the east coast of Scotland, approximately 80 km south-east of Aberdeen from the nearest point (see Figure 2.1 Open ▸ ).
The Array covers an area of approximately 859 km2. It comprises up to 265 floating wind turbines and up to 15 OSPs. Subsea inter-array cables will connect the wind turbines to each other and to the OSPs, while interconnector cables will connect the OSPs to each other.
All structures shall be lit once installed and shall use temporary lighting until the permanent lighting is in place. This includes the lighting of structures during towing from the integration port to the Array.

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Figure 2.1: Location of the Array

2.2. Consent Conditions

Table 2.1 Open ▸ lists the conditions of the Array consents relevant to lighting and marking. This LMP has been produced for the purposes of satisfying these conditions and has been prepared in accordance with relevant legislation, guidance and good practice.

Table 2.1: Consent Conditions Relevant to Lighting and Marking

This LMP is a live document and will be further developed in accordance with the requirements of the relevant consent conditions and in consultation with relevant stakeholders, post-consent.

3. Summary of Designed in Measures, Mitigation and Monitoring Included in the Array EIA Report

This section describes the designed in measures, mitigation and monitoring commitments adopted as part of the Array EIA Report in relation to lighting and marking. These are included by receptor and Array EIA Report chapter below.

3.1. Shipping and Navigation

Volume 2, chapter 13 of the Array EIA Report has identified all potential impacts and designed in measures relevant to lighting and marking. These are listed in Table 3.1 Open ▸ .

Table 3.1: Designed in Measures Relevant to Shipping and Navigation

Designed in Measures	Justification
Deployment of a buoyed construction area in agreement with the Northern Lighthouse Board (NLB).	Protects third-party vessels from project vessels involved in construction activities which may be RAM, and partially completed structures.
Development of, and adherence to an LMP.	The LMP will confirm compliance with legal requirements including IALA G1162 (IALA, 2021b), with regards to shipping, navigation and aviation marking and lighting to increases awareness of the Array in both day and night conditions for vessel and aviation operators including in restricted visibility and assists with SAR operations. Consideration of UK Marine Guidance Note (MGN) 654 with respect to wind turbine design and construction, so that recognised safe standards are met with regards to navigational safety and emergency response (search and rescue, salvage and towing, counter pollution).

Designed in Measures

Justification

Deployment of a buoyed construction area in agreement with the Northern Lighthouse Board (NLB).

Protects third-party vessels from project vessels involved in construction activities which may be RAM, and partially completed structures.

Development of, and adherence to an LMP.

The LMP will confirm compliance with legal requirements including IALA G1162 (IALA, 2021b), with regards to shipping, navigation and aviation marking and lighting to increases awareness of the Array in both day and night conditions for vessel and aviation operators including in restricted visibility and assists with SAR operations.

Consideration of UK Marine Guidance Note (MGN) 654 with respect to wind turbine design and construction, so that recognised safe standards are met with regards to navigational safety and emergency response (search and rescue, salvage and towing, counter pollution).

3.2. Aviation, Military and Communications

Volume 2, chapter 14 identified wind turbines causing interference on aviation radar systems as a likely significant effect (LSE1) and creation of physical obstacles affecting air traffic as a minor adverse significant effect. A designed in measure identified within this chapter is the preparation and implementation of an LMP which should set out specific lighting requirements in relation to aviation - to be installed on the wind turbines. Volume 2, chapter 14 of the Array EIA Report has identified all potential impacts and designed in measures relevant to lighting and marking. These are listed in Table 3.2 Open ▸ .

Table 3.2: Designed in Measures Relevant to Civil and Military Aviation and Radar

Designed in Measures	Justification
Development of, and adherence to a LMP	The LMP will confirm compliance with legal requirements with regards to shipping, navigation and aviation marking and lighting. Array aviation lighting will conform to the following: Red medium intensity aviation warning lights (of variable brightness between a maximum of 2,000 candela (cd)) to a minimum of 10% of the maximum which would be 200 cd) will be located on either side of the nacelle of significant peripheral wind turbines. These lights will flash simultaneously with a Morse W flash pattern and will also include an infra-red (IR) component. All aviation warning lights will flash synchronously throughout the Array and be able to be switched on and off by means of twilight switches (which activate when ambient light falls below a pre-set level). Aviation warning lights will allow for reduction in lighting intensity at and below the horizon when visibility from every wind turbine is more than 5 km (to a minimum of 10% of the maximum (i.e. 200 cd)). SAR lighting of each of the non-periphery wind turbines will be combi IR/200 cd steady red aviation hazard lights, individually switchable from the control centre at the request of the MCA (i.e. when conducting SAR operations in or around the Array). All wind turbines will be fitted with a low intensity light for the purpose of helicopter winching (green hoist lamp). All wind turbines will also be fitted with suitable illumination (minimum one 5 cd light) for identification signs.
Notification to the Defence Geographic Centre (DGC) and National Air Traffic Surveys (NATS)	Information regarding construction will be passed to the Defence Geographic Centre (DGC) (at dvof@mod.gov.uk) at least 10 weeks in advance of the obstacle type(s) erection detailing position, height (tip of arc) and type of aviation lighting. Once reported, all will be included in the DGC Obstruction database and all that meet aviation chart inclusion criteria will be published for broader awareness. Appropriate information about the site construction and any associated lighting (where applicable), for example the height and temporary location of construction cranes, should be provided to the National Air Traffic Surveys (NATS) Aeronautical Information Service (AIS) (for promulgation in applicable aviation publications including the UK Integrated Aeronautical Information Package (IAIP))
Emergency Response Co-operation Plans (ERCoP)	In line with MGN 654 (MCA, 2021a) Annex 5 SAR requirements.

Designed in Measures

Justification

Development of, and adherence to a LMP

The LMP will confirm compliance with legal requirements with regards to shipping, navigation and aviation marking and lighting. Array aviation lighting will conform to the following:

Red medium intensity aviation warning lights (of variable brightness between a maximum of 2,000 candela (cd)) to a minimum of 10% of the maximum which would be 200 cd) will be located on either side of the nacelle of significant peripheral wind turbines. These lights will flash simultaneously with a Morse W flash pattern and will also include an infra-red (IR) component.
All aviation warning lights will flash synchronously throughout the Array and be able to be switched on and off by means of twilight switches (which activate when ambient light falls below a pre-set level).
Aviation warning lights will allow for reduction in lighting intensity at and below the horizon when visibility from every wind turbine is more than 5 km (to a minimum of 10% of the maximum (i.e. 200 cd)).
SAR lighting of each of the non-periphery wind turbines will be combi IR/200 cd steady red aviation hazard lights, individually switchable from the control centre at the request of the MCA (i.e. when conducting SAR operations in or around the Array).
All wind turbines will be fitted with a low intensity light for the purpose of helicopter winching (green hoist lamp). All wind turbines will also be fitted with suitable illumination (minimum one 5 cd light) for identification signs.

Notification to the Defence Geographic Centre (DGC) and National Air Traffic Surveys (NATS)

Information regarding construction will be passed to the Defence Geographic Centre (DGC) (at dvof@mod.gov.uk) at least 10 weeks in advance of the obstacle type(s) erection detailing position, height (tip of arc) and type of aviation lighting. Once reported, all will be included in the DGC Obstruction database and all that meet aviation chart inclusion criteria will be published for broader awareness.

Appropriate information about the site construction and any associated lighting (where applicable), for example the height and temporary location of construction cranes, should be provided to the National Air Traffic Surveys (NATS) Aeronautical Information Service (AIS) (for promulgation in applicable aviation publications including the UK Integrated Aeronautical Information Package (IAIP))

Emergency Response Co-operation Plans (ERCoP)

In line with MGN 654 (MCA, 2021a) Annex 5 SAR requirements.

4. Guidance

International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) guidance for the marking of man-made offshore structures is contained in document number G1162 (IALA, 2021).
IALA (2021) provides guidance and information to stakeholders such as National Authorities, Lighthouse Authorities, Aviation Authorities and other competent Authorities, Aids to Navigation providers, and the Contractors, Developers and Operators involved with the offshore structures. The marking of offshore structures as defined in IALA (2021) will be considered as a minimum requirement to ensure the safety of navigation in the vicinity of the structures.
The MGN 654 published by the MCA provides recommendations and criteria to be taken into account by Offshore Renewable Energy Installations (OREIs) developers seeking formal consent for marine works regarding navigation safety or emergency response preparedness.
The following sections set out the lighting and marking specifications for the Array during construction, and operation and maintenance phases. The recommendations and proposals made in this LMP will be finalised in consultation with NLB, MCA, CAA and MOD.

5. Marine Navigation Safety

This section provides the minimum lighting and marking requirements for marine navigation safety of OREIs as defined in IALA guidance G1162 (IALA, 2021). It also outlines any proposed site-specific enhancers relevant to lighting, marking, sound signal and radar.
Marine aids to navigation will be provided throughout the lifetime of the Array in accordance with the requirements of the NLB.
Figures showing the confirmed marine lighting and marking for the Array will be included in the version of this LMP submitted for approval post-consent.

5.1. Lighting Requirements to Protect Marine Navigation Safety

Lighting requirements are provided in this section, in accordance with IALA (2021). These are summarised in Table 5.1 Open ▸ .
When considering offshore wind farms, IALA (2021) includes the following structures: meteorological mast, wind turbine and offshore transformer/substation.
IALA (2021) classifies offshore wind farm structures as follows:

Significant Peripheral Structure (SPS), which includes the structures on the corners and other structures on the periphery of the wind farm as decided by the competent authority, normally not exceeding a 3 nm distance;
Intermediate Peripheral Structure (IPS), which includes selected locations on the periphery of the wind farm, normally not exceeding 2 nm separation; and
All other wind turbines not classified as either SPS or IPS.

Table 5.1 Open ▸ provides the requirements for the lighting of offshore structures for marine navigation in accordance with IALA (2021).

Table 5.1: IALA Requirements for Marine Navigation

Offshore Structures	Colour Lighting	Minimum Height (m)	Maximum Height (m)	Visibility Range (nm)	Availability
SPS	Flashing yellow, synchronized	6 m above Highest Astronomical Tide (HAT)	30 m above HAT (and below lowest blade tip height)	5	99%
IPS	Flashing yellow, synchronized	6 m above HAT	30 m above HAT (and below lowest blade tip height)	2	99%
All other wind turbines	None	None	None	None	None
Meteorological Masts and Other Individual Structures	Flashing white	6 m above HAT	30 m above HAT (and below lowest blade tip height)	10	99%

5.1.1. Proposed Measures

The proposed lighting requirements ( Table 5.1 Open ▸ ) have been defined during IALA (2021) and are subject to agreement with the NLB and the MCA.
MCA (2022) states that “SPS will be marked with lights visible from all directions in the horizontal plane. These lights should be synchronized to display simultaneously an IALA “special mark” characteristic, flashing yellow, with a range of not less than five (5) nautical miles. Aids to navigation on individual structures are placed below the arc of the rotor blades, typically at the top of the yellow section”. Also that “(IPS) on the boundary of a wind farm between SPSs will be marked with flashing yellow lights (typically yellow with a 0.5s flash every 2.5s) which are visible from all directions horizontally. The characteristics of these lights areas differ from those displayed on the SPSs, and have a range of not less than two (2) nautical miles. The distance between such IPS or the nearest SPS should not exceed two (2) nautical miles”.
The use of working lights, such as down lighting on ladders and access platforms, must not reduce the visibility of marking lights. Furthermore, it is recommended they are switched off when personnel are not working on, or at, the structure (IALA, 2021).
Marine navigation lighting will be remotely controlled by the Supervisory Control and Data Acquisition (SCADA) system and will be visible at night and turned off during the day.

5.2. Marking Requirements to Protect Marine Navigation Safety

IALA (2021) recommends that wind turbines, meteorological masts and offshore transformer/substation are painted yellow from the level of HAT up to at least 15 m.
MCA (2024) requires that each of said structures display identification panels with black letters or numbers. ID numbers must be clearly readable by an observer stationed three metres above sea level at a distance of at least 150 metres from the turbine. Each ID number plate shall be illuminated by a low intensity light visible from a vessel thus enabling the structure to be detected at a suitable distance to avoid a collision. Lighting for this purpose must be hooded or baffled so as to avoid unnecessary light pollution or confusion with navigation marks.

5.2.1. Recommendation

All wind turbines foundations to be painted yellow (RAL 1023 or similar) up to the interface level between the foundation and tower.
All OSP foundations to be painted yellow (RAL 1023 or similar) from the level of HAT up to at least 15 m above HAT.
All wind turbines and OSPs shall have identification plates consisting of a unique alphanumeric identifier of black letters and numbers. Characters shall be at least 1 m in height such that they are clearly readable by an observer stationed three metres above sea level at a distance of at least 150 metres from the turbine Three identification plates shall be positioned around the working platform so that at least one identification plate is visible from every direction. Each identification plate will be illuminated by a low-intensity light, so it is clearly readable at night. Lighting will be hooded or baffled so as to avoid unnecessary light pollution or confusion with navigation marks.
Any specific requirements in relation to floating structures will be addressed post-consent and included in the final version of this LMP submitted for approval.

5.3. Cumulative Lighting and Marking

Details/information regarding cumulative lighting and marking requirements (following discussion with NLB) will be confirmed post-consent.

5.4. Sound Signal Requirements to Protect marine Navigation Safety

IALA (2021) provides guidance on the marking of offshore structures by using Hazard Warning Signals (HWS), with the following recommended requirements:

located not less than 6 m and not more than 30 m above HAT;
have a minimum range of 2 nm;
have the character Mo (U) 30 s with a minimum duration for the short blast of 0.75 s; and
are operated when the meteorological visibility is 2 nm or less. For this, a visibility detector will typically be used.

5.4.1. Recommendation

The Array shall have sound signals installed on the wind turbines along the perimeter of the Array, likely on the SPS. The exact number, locations and minimum spacing of sound signals to be used at the Array will be determined once the wind turbine layout has been finalised prior to construction, however.

6. Air Navigation Safety

This section details the minimum specification for lighting and marking requirements for air navigation safety, in accordance with the requirements of the CAA and MCA. All such requirements will be finalised when a final wind turbine layout is established.
Figures showing the confirmed marine lighting and marking for the Array will be included in the version of this LMP submitted for approval post-consent.

6.1. Lighting Requirements to Protect Air Navigation Safety

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. Marking Requirements to Protect Air Navigation Safety

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).

7. Construction Phase

7.1. Marine Lighting and Marking During Construction

During the construction phase of the Array, all structures regardless of construction status will be marked with temporary flashing yellow 2.5 seconds lights (visible through 360°) with a 2 nm range. It is likely that two lights per structure will be used to ensure 360° visibility. Requirements for the lighting of structures during towing operations will be agreed with relevant stakeholders post-consent.
Temporary construction buoyage will be in place during the construction phase at the Array. This will be a combination of cardinal marks and special marks. Specifications of each buoy are to be agreed with NLB.
Likewise, the lighting and marking requirements for the transition to the operation and maintenance phase, including a process for the removal of temporary lighting and buoyage and approval of permanent lighting, will be agreed with NLB as the construction programme is developed.

7.2. Aviation Lighting and Marking During Construction

Aviation lighting or marking to be implemented during the construction phase will be agreed with CAA as the installation methodology, sequencing and programme are developed and finalised. The Applicant will undertake promulgation of information to the relevant aviation authorities and stakeholders prior to, and during construction.
The lighting and marking requirements for the transition to the operation phase will be agreed with CAA as the construction programme is developed.

8. Wind Farm Layout Numbering

Unless otherwise agreed by the MCA, the numbering of the wind turbines at the Array shall follow the MCA (2021a) guidance. This numbering should be sequential, aligned with ‘SAR lanes’ and begin with the OREI name designator code, then the row/column numbering starting with ‘A’ and then the wind turbine number.
The identification marking must be discussed with the MCA who will advise on any specific requirements for the Array. This will be confirmed once layouts have been finalised.

9. References

CAA (2016). Policy and Guidelines on Wind Turbines (CAP 764). Available at: CAP764 Issue6 FINAL Feb.pdf (caa.co.uk). Accessed on: 27 May 2024.

CAA (2021a). Standards for offshore helicopter landing areas (CAP 437). Available at: Standards for offshore helicopter landing areas (caa.co.uk). Accessed on: 27 May 2024.

CAA (2021b). CAP 393: Regulations made under powers in the Civil Aviation Act 1982 and the Air Navigation Order 2016. Available at: Regulations made under powers in the Civil Aviation Act 1982 and the Air Navigation Order 2016 (caa.co.uk). Accessed on: 27 May 2024.

IALA (2021). G1162 The Marking of Offshore Man-Made Structures. Available at: G1162 Ed1.0 The marking of offshore man-made structures - IALA AISM (iala-aism.org). Accessed on: 27 May 2024.

IMO (1972/77). Convention on International Regulations for Preventing Collisions at Sea (COLREGs) – Annex 3. London: IMO.

IMO (1974). International Convention for the Safety of Life at Sea (SOLAS). London: IMO.

MCA (2021). MGN 654 (M+F). Offshore Renewable Energy Installations (OREIs) Safety Response. Available at: MGN 654 (M+F) Offshore Renewable Energy Installations (OREI) safety response - GOV.UK (www.gov.uk). Accessed on: 27 May 2024.

MCA (2022). MGN 372 Amendment 1 (M+F) Safety of Navigation: Guidance to Mariners Operating in the Vicinity of UK Offshore Renewable Energy Installations (OREIs). Southampton: MCA

MCA (2024). Offshore Renewable Energy Installations: Requirements, guidance and operational considerations for SAR and Emergency Response (MGN 654 Annex 5). Available at: Offshore Renewable Energy Installations: Requirements, Guidelines and Operational Considerations for SAR and Emergency Response (publishing.service.gov.uk). Accessed on: 27 May 2024.

RYA (2019). The RYA’s Position on Offshore Renewable Energy Developments: Paper 1 (of 4) – Wind Energy. 5th revision. Southampton: RYA.

Reference	Consent Condition
[To be added post-consent]