Agree with you Harry - the winch is much maligned - but the stats Tim
points to do seem pretty irrefutable - suggesting winching requires a
skill level above and beyond that needed for aero-tow and that winch
technique is generally a weakness in the training curriculum. I'd also
add lack of currency checks to the latter.
I learnt to fly on a high tensile single wire winch in the rough and
tumble and abrasive red dust of Bond Springs aerodrome, up on the edge
of the Tanami plateau north of Alice. In some ways the frequent wire
breaks there were a godsend. The assumption on launch was that wire
would break. Any launch completed without a break was a bonus.
I had a wire break at 200 feet on my second solo, a wire break at 400
feet on my third solo and, to top it off, a winch failure (ran out of
fuel) at 600 feet on my fifth solo. The latter was particularly
interesting as the power loss was gradual not precipitative. The first
two involved a straight in landing ahead and the third a modified cct.
for a mid down wind entry back onto the strip.
My view - executed correctly there is no point in a winch launch where
in case of launch failure it is not possible to release, recover and
land back on the active strip.
This is definitely a learnt skill and one that does not automatically
stick with you if not practised.
Best technique hints that made the whole arrangement work like a
dream every time:
- Centre stick pre-roll for best assessment of a two point pitch
attitude.
- Do not operate the stick in the early stages of the ground roll
other than to adjust yaw balance and confirm or establish correct two
point fore/aft attitude.
- When the aircraft has sufficient speed it will decide lift off.
- Positively identify the ASI moving upwards through 40Kts.
- Pull back on the stick about a centimetre or at max two finger widths.
- All things above being in order, without further stick input the
aircraft will rotate itself to best (i.e. safest) climb attitude and
stick there with minimal overshoot.
- As soon as the climb attitude is established check left and right
for yaw attitude, begin to assess wind drift correction and, just to
be completely anal about it, deliberately acknowledge that the
airbrakes are fully locked away.
- Feel for and positively identify you have clear access to the yellow
release bung.
The rest of the launch as per normal re: pitch adjustment for
airspeed, adjustment for crosswind and maintaining situational
awareness.
This arrangement may not achieve the absolute possible max launch
height possible but it does increase the probability you will remain
mid-envelope throughout the launch - and that means max options on
launch failure.
Dion Weston
On 28/05/2010, at 20:30 , harry medlicott wrote:
Hi All,
My own experiences re winch launching and safety be of interest. I
learnt to fly using the winch at Warkworth. To the best of my
knowledge never an accident using the winch in the years they were
using one. Helped establish the Central Coast Gliding Club and was a
busy instructor there. They were doing 3,000 winch launches per
year. In the 15 years I was there and so far as I know after that no
accidents - a time span of nearly 30 years. Moved to LKSC nearly 15
years ago. The club and its precursors have been using a winch, very
extensively for mid week training for some time, again no winch
launching accidents to my knowledge over 40 years which goes back
well before I started gliding so cannot be certain.
As against that there have been 4 aerotow accidents involving 5
deaths where I have personally known the people involved. in two
cases a midair during the launch, another was a tug wing structural
failure and in another the tug pilot dropped the glider just before
a fence.
Have been dedicated to safety for all my gliding career and
carefully studied all aspects.The British, who perform about 300,000
winch launches per year and have accurate records going back 35
years have carefully analysed all accidents and have identified
causal factors. We in Australia can learn from their conclusions and
reccomendations. As an example in Great Britain, there is an
accident involving injury when a glider cartwheels due to wing drop
and catching the ground about once every 400,000 launches, Once a
cartwheel starts it is unrecoverable and pilot injury almost
certrain. The conclusion and advice. Keep a hand on the release
during the early part of the launch - no time to grab it if things
start to go wrong. If you cannot keep the wings level and a wing is
about to touch the ground, release immediately. Might be an
inconvenience and a 99% chance you would get the wing up but if all
pilots released as advocated then that 1 in 400,000 occurence would
not occur. The same applies to all other possible reasons for an
accident. At Lake Keepit usingDyneema rope and a world class winch
the chance of a rope break/ power failure is remote but can still
happen. Adequate training is essential. Maintaining LKSCs perfect
winch safety record is my priority..
The undisputed fact is that a winch pilot can either avoid or safely
handle every conceivable situation which might occur on a winch
launch. Even if a winch driver deliberately tried to cause an
accident, the pilot can control the situation. Believe that if
something goes wrong it is an instruction failure rather than pilot
error.
Safe flying,
Harry Medlicott
Harry
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