Design guidelines for obstruction lighting at wind farms
The following explanations are guidelines meant to help developers, project engineers and designers when considering the installation of obstruction lighting for a wind farm. A wind farm is defined as 3 or more wind turbines, each with a total height equal to or less than 150m (500ft). The implementation of these guidelines will help pilots recognize the obstacles as a wind farm as opposed to other types of obstructions.
The application of these requirements can vary depending on terrain features, geographic location, overall layout of the structures, and normal approach angles.
GUIDELINES (150m OR BELOW)
The group of wind turbines that make up a wind farm shall be indicated to pilots by the installation of red flashing beacons (L-864 or CL-864 medium intensity) on specified wind turbines on the perimeter of the wind farm.
The wind turbines on which the red flashing beacons are installed shall be spaced at an horizontal distance in the order of 900m (1/2 statute mile) for given directions of aircraft approaches.
The dominant [highest in absolute height] wind turbine within the wind farm also needs to be lit with a red flashing beacon. This requirement for lighting depends on the degree of dominance deemed to produce a hazard to air navigation.
Because of the variations in wind farm configurations, the provision of lighting shall also be subject to a risk assessment, taking into account such factors as:
- the general profile of the group,
- the location of the wind farm in relation to nearby aerodromes or recognized VFR flight routes,
- the anticipated air traffic.
All indicator lighting provided for a windfarm shall flash simultaneously.
Note: these guidelines were prepared based on FAA Advisory circular on Obstruction Lighting (AC 70/7460-1K) and Transport Canada’s Obstruction Marking and Lighting Standards (Standard 621).
GUIDELINES (150m TO 315m)
As of March 1st, 2016 Transport Canada adopted new rules for the lighting of MET Towers as well as wind turbines that have a tip height over 150m.
WIND TURBINES ABOVE 150m
As per the diagram below, two CL-864 beacons must be installed on the nacelle (the second beacon is there only in case of failure of the first), and 3 CL-810 side lights must be installed on the mast at mid-height. The side lights must flash in synchronicity with the beacon on the nacelle.
As is illustrated in the figure below, MET Towers that are 60m or more in height must utilise the following obstruction marking configuration:
(a) Marker balls on the outer guy wires near the top of the tower;
(b) The Tower is lit for night pruposes as per configuration (A) and the mast of the tower is painted in a banded pattern as stipulated in 3.5(3); and
(c) High visibility sleeves on the outer guy wires close to the anchor points, but at a height above the expected crop/vegetation canopy.