Can wind farms make light aircraft pilots fall out of the sky?

In a recent post, Troppo’s Ken Parish suggested that quality newspapers serve a gatekeeping role, ensuring "at least some measure of quality assurance". So what’s happening at the Australian?

In a recent piece on wind farms, environment editor Graham Lloyd attempted to explain how wind turbines kill birds and why wind farms can’t be built close to airfields:

There is a common misconception that birds are sliced up by wind turbine blades, which appear to be spinning slowly but are actually travelling at speeds of up to 200km at the tip. In fact, birds die when they encounter the windshear and pressure changes caused by banks of wind turbines churning up the air. They literally pop and fall out of the sky. This is why there is a ban on wind farms being built near airfields, lest light aircraft pilots meet the same fate.

Lloyd seems a little confused. While there is some evidence that bats can be killed by a sudden drop in pressure caused by flying too close to the tips of a turbine’s blades, this isn’t how most birds are killed. Birds typically die after colliding with blades.

A study by Erin Baerwald, Genevieve D’Amours, Brandon Klug and Robert Barclay (pdf), reported that "Even if echolocation allows bats to detect and avoid turbine blades, they may be incapacitated or killed by internal injuries caused by rapid pressure reductions they can not detect." These pressure changes cause air in the bats’ lungs to expand leading the small blood vessels around the edges of the lungs to burst — a process known as barotrauma. But according to the researchers:

Birds are also killed at wind turbines, but at most wind energy facilities fewer birds than bats are killed, and barotrauma has not been suggested as a cause of bird fatalities.

As for the idea that pressure changes will cause light aircraft pilots to fall out of the sky like bats, this seems unlikely. According to Baerwald, the zone around the blade tips in which pressure suddenly drops is only a metre or so in diameter. The major reason wind farms aren’t allowed near airfields is because pilots might fly into them — especially at night.

5 thoughts on “Can wind farms make light aircraft pilots fall out of the sky?

  1. I suppose now’s a good time to remember John Quiggin’s observation that:

    … journalists have to distil, from interviews, and to a deadline, a readable, and at least half-way accurate, story about a topic of which they may know little or nothing when they start. This is a difficult skill to acquire, and something we should remember when we complain that, on any subject where we are well informed, the media stories we read or see are often wrong in at least some important detail.

  2. I am all for heeding John Quiggin’s observations on all sorts of things, but this is one occasion when we might just say that the journalist involved just did really bad work.

    Lloyd’s observations on the effects of the blades were new to me. And I took them as the mark of someone who knew what he was talking about. They suggested a command of the subject.

    If he simply reported some piece of rumour as fact, then he’s just not very good.

    I also remember reading it and reflecting that air being the sort of fluid it is, I would have expected the air effects to be much more localised. Lloyd should have thought the same thing, and should have double-checked.

    But the sad truth is that he’s not alone amongst journalists in having a weak bullshit-detector. The mainstream media’s gatekeeping role is just not very strong. Blogging, commenting and the like are showing that in writing on technical subjects, crowd-sourcing is a far better source of quality control.

    (Don, if you’re wrong, everything above is invalid. My only compensation is that this being the blog it is, if you’re wrong, I’ll know fairly soon.)

  3. Is there even a ban on wind farms near airfileds? Surely it’s the general ban on tall structures would make that moot.

    And of course the low (and high) pressure fluctuations from individual blades would be localised within metres. The only effect from a greater distance – reduced wind speed – would if anything improve air safety.

  4. Talk about weak bullshit detectors.

    The other day in the AGE Gerry Harvey in an attack on online purchases – is reported as saying that shonky stores were able to buy goods online, avoid GST and import duties and then sell 50% below what “good” stores like his were selling.

    This was just reported as fact.

    No questioning of Harvey – or – “He would say that wouldn’t he”

    No asking him how he knew and what he had done about reporting these rogues to authorities.

    No wondering if he needs a bit of publicity prior to xmas.

    No wondering if this is a pre-emptive shot in an effort to stop people shopping online.

    No asking him how his stores in Ireland were going….

    Firstly GST is only 10% and most import duties are 10% or below.

    Then anyone bringing in goods has to pay transport or postage.

    How on earth this then adds up to an “unfair” advantage and the ability to sell at 50% below Harvey Normans prices is beyond me.

    Are we really expected to believe that some people are bring in enough BBQs, couches and fridges duty free and GST free to be able to set up in competition to HN?

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