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Old 03-17-2013, 09:56 PM
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newt newt is offline
Join Date: Jan 2011
Location: Sydney, Australia
Posts: 443

Video of low altitude flight through river valleys scares the heck out of me. Valleys always have wires hanging from one side to the other, waiting to catch pilots who haven't seen them.

Not sure how electricity is distributed to farmhouses in the USA, but in Australia it's very common for utilities to use Single Wire Earth Return (SWER) systems.

SWER systems use a wire about the same gauge as fencing wire to carry 12.7kV on wood or steel/concrete poles about a quarter mile apart over distances of anything up to 30 miles.

The utilities seem to try their best to make the poles visually unobtrusive by putting them in groves of trees or scrub, or along existing fence lines where they won't interfere with agricultural machinery. And the wire is tiny, essentially impossible to see. Generally the only way you'll know they're there is by looking for a characteristic teardrop pattern around the base of each pole caused by the farmer's plough diverting around it, then by scanning out by approximately a quarter mile to find the next pole... And the next... And the next. But even that cue is absent if the poles are on fence lines or in trees.

And even then you won't know if you've found them all because the wires sometimes branch from poles to feed multiple nearby properties. Maybe you've missed a branch!

The upshot is that even flat, clear-looking, isolated terrain miles from civilization can be cross-crossed with wires on almost invisible 30 or 40 foot poles.

I know of at least one fatality caused when a pilot recovered an aircraft from an off-field landing in a valley. There was an unseen SWER line in his takeoff path; one pole was on the crest of the hill on one side of the valley, the next was on the crest of the hill on the opposite side, and the wire hung invisibly in an arc between them. Nobody knew it was there until the aircraft hit it.

So yes: low flying is so far below my personal minimums that it isn't even on the agenda. Except in very limited situations which I'm never likely to encounter in my flying career (such as well surveyed crop duster ops, perhaps), I just don't see how it can be done safely in my part of the world.

- mark
[ Paid up on 16 Jul 2021 ]
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