After warning a wind farm developer that its turbines would interfere with airport radar systems in London and Hamilton and reduce flight safety, NAV Canada says it’s no big deal.
In a letter dated Aug. 14 to the developer of the Gunn’s Hill wind farm near Woodstock, Canada’s civil air navigation service provider states all 10 of the planned turbines are visible to the London radar and four are visible to the Hamilton radar.
The impact, NAV Canada says in the letter, includes “a decrease in flight safety for aircraft operating in the area, especially in adverse weather conditions.”
The letter also states the Gunn’s Hill wind turbines will increase the workload of air traffic controllers and reduce NAV Canada’s ability to identify and track surveillance targets in the area.
“The final assessment is that the risk increase presented by this proposal may require mitigating actions. Therefore NAV Canada will require an agreement for cost recovery should mitigation measures be needed,” the letter to Juan Anderson of Gunn’s Hill Windfarm Inc. states.
But a NAV Canada spokesperson on Friday said the problem of wind turbine interference with airport radar can easily be fixed by software.
“This shouldn’t be too much of a problem,” Ron Singer of NAV Canada told The Free Press.
The problem for air navigation radar systems is that the turning wind turbine blades can appear as a moving object on the radar screen, a false target.
“There is a software adjustment that can be made, and we work with wind farm developers so it will not be a problem,” Singer said.
Wind turbines only affect what’s referred to as the primary radar system – one that detects moving objects but doesn’t identify the aircraft.
Air traffic controllers rely more on a secondary radar system that detects transmissions from aircraft transponders. That information identifies the aircraft, its speed and altitude, Singer said.
“Any commercial flight would have a transponder. The small, little added level of safety concern is easily mitigated.”
But the association that represents the owners of small aircraft and pilots in Canada doesn’t see wind turbine interference as a small problem.
“It’s very much a concern,” said Kevin Psutka, president of the Canadian Owners and Pilots Association.
The software fix for wind turbine interference involves relying on other radar systems for areas blotted out by wind turbines. That’s what is being done to avoid interference from a major wind farm on the north shore of Lake Erie, Psutka said.
But that solution isn’t available everywhere in Canada because there isn’t always other radars to fill in the gap, Psutka said.
The secondary radar system that relies on transponder signals can’t detect aircraft that don’t have transponders or instances where transponders are deliberately shut off.
“If someone wanted to sneak into Canada, they could do it at low levels behind a wind farm,” Psutka said. “It is a security concern.”
Wind farms can also be a problem for weather radar, making it more difficult to detect severe storms.
In approving wind farms near the Exeter radar that serves Southwestern Ontario, the Ontario Ministry of Environment has stipulated that mitigation measures have to be agreed upon between the wind farm developer and Environment Canada before the turbines start operation.
Measures might include shutting down wind farms during severe weather events.
Environment Canada has said it plans to test software this fall aimed at overcoming wind turbine interference of its radar system. The U.S. Weather Service has also said it’s working on a solution, but is at least five years away from solving the problem.
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