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Old August 16th 07, 01:01 PM posted to rec.aviation.soaring
Bruce
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Default Winching (European tips for US clubs)

Relative safety or danger of winching depends on lots of things. It all comes
down to stacking the odds in your favour, considering the four factors involved:
Weather, wind makes a much bigger difference when you are attached to the earth
by a string.
Field topography, winch fields need to have options for landing from a wider
range of heights over the runway.
Aircraft performance, aerotow tends to homogenise performance, you get what the
tug can do most of the time. Winch accentuates differences, and changes your
options dramatically.
Pilot capability, changes day to day, and incestuously with the other three.
Can't assume that the pilot who has no problems with the big slow two seater
will be able to judge the recovery procedure correctly first time in the glass
single.

In my experience what causes accidents is people failing to objectively assess
the permutation presented.

Physical layout of the site may make it difficult for certain gliders under
certain circumstances to land safely with a cable break or winch failure in a
certain height band. European clubs often launch out of very short fields with
limited options if things go awry. My home club has an ideal runway for
winching, with angled launch points leading into the main runway inset ~200m
from the threshold. We never launch with another aircraft on base or finals, as
there is no point in looking for danger. But we could do so without conflict, as
a well judged landing has the lander stopped opposite the launch point.
Conversely at another club I fly at - launching up hill on a shorter runway with
the Twin Astir in light wind has a window where there are few good options. In
these conditions there is always a discussion of the options and decision points
before the canopy closes. No matter who is flying. We teach that a cable break
is a normal manoeuvre - not an emergency. If you don't know how you are going to
avoid damage or injury if there is a launch failure you should decline the launch.

The operating envelope is reduced, as others have noted, but not dramatically
so, and not at the expense of safety. I expect the higher incidence of winch
accidents / injuries is diagnostic of the relative number of launches, with a
bit of complacency thrown in.

Personally I have found being dragged kilometres from the runway at low level
with the airspeed in the yellow arc far more worrying than any of the many winch
launch failures I have had. You are far more exposed to circumstances and poor
decision making (your own and the tuggie's) on an aerotow, and for a lot longer.
The converse is also true, when the right decision may be to not fly, there are
two pilots who have to make the mistake to decide to launch an aerotow
combination.




Tom Gardner wrote:
On Aug 16, 12:29 am, Dan G wrote:
My tip would to be concentrate on safety. It is of utmost importance
that a glider can also recover from a launch failure no matter when
during the launch it occurs.


Too true, but...

That sounds simple but in reality it's
quite complex: it mandates that the glider is flown in a very precise
and quite narrow envelope during the launch, particularly the first
part, and what you actually do in the event of a failure is totally
dependent on the layout of the airfield and wind speed and direction.


Isn't the same true with aerotows?

I was taught (and it was demonstrated) that in still air a K13
will get itself into the air correctly without significant pilot
input. I exaggerate slightly, of course

You need very experienced people to teach you what to do.


And a "good" site. I've heard rumours of sites where, if there is
a break at certain heights, you are almost guaranteed to end
up in some trees. I wonder if that is true or merely a bar story.

Certainly the site was a major factor in my choosing a club;
the target zone is very large, and there is an embarrassment
of options.

The BGA has produced excellent safety advice, read it he
http://www.gliding.co.uk/bgainfo/doc...hlaunching.pdf


That's a useful aide memoire, but recent local experience is more relevant and necessary.

However, if you don't follow that advice, this is what happens:
http://www.aaib.gov.uk/cms_resources...2020L%20glider,...


True, but there are equivalent considerations with aerotow failures,
plus you can kill the tuggie.

tom gardner