Offshore Wind Farm Helicopter Search and Rescue Trials

Executive Summary

These trials follow on from those undertaken by the Maritime and Coastguard Agency in conjunction with QinetiQ and Npower Renewables at the North Hoyle offshore wind farm in July 2004 ¹. These had been carried out at North Hoyle with the co-operation of Npower since, at that time, it was the only large area offshore wind farm in United Kingdom waters.

No critical assessment of search activities within and close to offshore wind farms had previously been carried out and the trials indicated that marine and shore-based radar systems would suffer some adverse effects when in their proximity. However no experimentation involving aircraft systems was made at that time.

Therefore, in co-operation with C Flight, 22 Squadron, RAF Valley, it was suggested that trials involving search and rescue helicopters should be carried out. These took place on March 22nd 2005, using a Sea King Mark lll aircraft.

The results indicated that :

• Radio communications from and to the aircraft operated satisfactorily, as also did its VHF homing system.
• Vessels, turbines and personnel in the wind farm were clearly identifiable on the aircraft’s thermal imaging system when operating in dry weather conditions.
• No compass deviation was experienced.

However, there could be limitations on the use of helicopters in offshore wind farms, due to :

• Significant radar side lobe returns from structures, limiting target detection when vessels were within 100 metres of turbines.
• The current inability of some wind farms operators to remotely lock turbine blades in rotation and in yaw.
• Limitations in approach distances from turbines in clear weather.
• Inability to effect surface rescues within wind farms in restricted visibility.
• Limitations of helicopters as radar search platforms if the wind farm was large and had irregularly spaced turbines.
• Limitations in the use of thermal imaging in conditions of mist or precipitation.
• Tracking, by vessel or shore-based marine radar, of helicopter movements within wind farms was generally poor.
• Increase of aircraft power requirements downwind of the wind farm.

Other factors which the previous trials had identified for further assessment were :

• The potential for reflected radar signals from turbines triggering RACONS. This was currently under investigation by Trinity House Lighthouse Service.
• The effects of offshore wind farms on short range radio systems. OFCOM had been offered participation in the trials, but did not wish to do so at that time.

Acknowledgments :

A number of individuals, companies and organisations took part in these trials.

The most vital contribution was of course that of ‘C’ Flight, 22 Squadron, Royal Air Force, Valley, Anglesey, under the command of Squadron Leader J.M.Stanley

Amongst others, the project manager and the Maritime and Coastguard Agency would particularly like to record their appreciation for the contributions of the following :

Broken Hill Proprietary Billiton Ltd.,

The Environment Agency, Buckley

NPower Renewables Ltd and the crew of “Celtic Wind”

Trinity House Lighthouse Service

The Royal National Lifeboat Institution

Paul Frost, 2nd Mechanic of the Rhyl Lifeboat Station

Carl Davies, skipper of “Lady Gwen II”

and

HM Coastguard, MRSC Holyhead, Anglesey.

¹ “ Results of the electromagnetic investigations and assessments of marine radar, communications and position fixing systems undertaken at the North Hoyle wind farm by QinetiQ and the Maritime and Coastguard Agency” MCA Report MNA 53/10/366 of 15.11.04