Under the Civil Aviation Safety Authority (CASA) visual flight rules, pilots must have good visibility, fly at sub-sonic speeds and must not fly lower than 500 feet above the highest point in the terrain or any object on it. This is well above the height of any part of a wind farm.
Do Wind Farms Impact Agricultural Aviation? (AusWEA Wind Fact 11)
"The pilots of crop dusting or super phosphate fertiliser spreading aircraft are highly skilled and are easily able to negotiate between the wind turbines which are normally positioned hundreds of meters apart. These pilots regularly navigate other less obvious hazards such as power and phone lines. During the wind farm design phase, landowners (and in some cases pilots) are consulted on the position of wind turbines, particularly any machines near the approach and takeoff paths of unregulated rural airstrips."
By Tristan Edis (Climate Spectator)
The Australian newspaper also carried the claim that wind farms could endanger the viability of Australia's entire banana production. The report cites horticulturalist Steven Lavis, saying that the banana crop "relied on aerial spraying that would not be possible within 5km of wind turbine towers."
So we called the Civil Aviation and Safety Authority whose media spokesperson told us, "That's just silly.” He explained that a wind turbine tower is just like any other obstacle that an agricultural aerial spraying pilot would need to take into account, such as powerlines and trees, and the decision as to where they could safely spray would be their own decision to make.
If anyone has seen aerial spraying of an agricultural crop they'll realise that these pilots will often fly quite close to a range of obstacles. Why wind turbines would need a 5km buffer, while they appear happy to fly within 100 metres of other dangerous obstacles such as powerlines, appears to defy explanation.”
Spraying operations are normally conducted at low altitude and often require calm or very light wind conditions – agricultural operators have stated that generally they operate in wind conditions up to 15km/h. At wind speeds of 15km/h, the proposed wind turbine generators are either not rotating or rotating minimally and hence the agricultural operations would not be affected.
- The wind turbines are usually located on elevated undeveloped ground and reasonably removed from the surrounding agricultural land. As spraying and spreading operations are normally conducted within a height of 90m above ground level, the aircraft is well below the level of the wind turbines on the wind farm site. In the case of the Mt Emerald Wind Farm, the farm is roughly 300m above the surrounding land.
RATCH-Australia have committed to work in liaison with the aerial spraying industry to identify communication regimes and consider turning off selected machines for the short term duration of spraying events immediately adjacent to its wind farms. This is likely to be a few hours for a few days per year.
Current aviation safety guidelines require that objects over 110m should be marked with hazard lighting, however Civil Aviation Safety Authority (CASA) are presently considering increasing this limit to 150m which would remove the requirement for lighting. If the wind farm is determined to require night-time hazard lighting, the lights will be located on the body of the wind turbine and will include shielding to limit the lighting to areas above a horizontal plane, level with the hub height of the turbine.
Given the wind farm site is 300m above the surrounding land and allowing for a 1° down angle, the lights will be shielded to a distance of approx 17km from the wind farm.
Night time obstacle lighting
Under the Civil Aviation Regulations, the Civil Aviation Safety Authority (CASA) may determine that an object or a proposed object which intrudes into navigable airspace requires, or will be required to be provided with, obstacle lighting.
The relevant Legislation Section 2.1.2(b) states that “outside the obstacle limitation surfaces of an aerodrome, if the object is or will be more than 110m above ground level.”
High intensity obstacle lights are flashing white lights used on obstacles that are in excess of 150m in height. As high intensity obstacle lights have a significant environmental impact on people and animals, it is necessary to consult with interested parties about their use. High intensity obstacle lights may also be used during the day, in lieu of obstacle markings, on obstacles that are in excess of 150m in height, or are difficult to be seen from the air because of their skeletal nature, such as towers with overhead wires and cables spanning across roads, valleys or waterways.
This is assessed on a case-by-case basis. All RATCH-Australia wind farms will be subject to this evaluation as part of the approval process.