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Old October 7th 13, 09:24 AM posted to rec.aviation.soaring
Don Johnstone[_4_]
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Posts: 398
Default Keep your hand off the release handle during aero tows!

I'm not basing this entirely on the AAIB report - I can read between the
li=
nes and I have other sources. No, the AAIB didn't address those issues
alt=
hough they certainly should have. =20

Instead, they ignored a wealth of obvious facts and blamed the accident

on
=
the release position which has worked just fine in literally millions of
re=
leases. Even so, if the owner, or a maintenance shop, thought there was

a
=
problem, adding a flexible release extension is SOP. Such an extension

is
=
even shown in Figure 5 with the release T-handle BEHIND the stick.

Figure
=
6 showing a 'pilot' with his RIGHT hand blocked from reaching a release

is
=
grossly misleading. I hope the AAIB doesn't risk its reputation by
present=
ing this argument in court.


OK, try sitting in a Schemp Hirth or even and ASW 17/19/20 with the stick
full to the left and try finding the release knob if you do not actually
have your hand on it. The time you have to realise you have a problem and
react is very short, trying to find the release will take longer than the
time you have.

Independent sources the glider was not pointing at the winch and, John,
eve=
n you suggest that's acceptable. I say the rope must be dead straight

and
=
the glider pointed exactly at the winch - no exceptions. This accident is
a=
great example of why.


Actually the glider should point down the direction if the initial cable
run, of course that should be the same as the direct line to the winch.

I've been officially involved in very similar accidents where the launch
cr=
ew had far less time yet DID stop a launch in time to save a pilot who
fail=
ed to release. Your crew had plenty of time to stop the launch. If the
si=
gnaling system didn't permit such a timely signal, that's yet another
probl=
em that needs to be addressed.=20


Not so, anyone with any experience of winch launching would know that the
time taken for a stop signal to be sent, received by the winch driver and
reacted on is way more than the time taken for the event you are trying to
prevent being over.

Clearly the acceleration was VERY slow and the wing did drag so the roll
wa=
s wobbly. Rolling 29m (95 feet) into a 15 knot headwind component proves
i=
t. A dry N3 with flaps set for winch launch lifts off below 33 knots so
wi=
th the headwind, the winch only had to add 18 knots which requires less
tha=
n one G for less than one second over a distance of less than 20 feet.

=20

All winches, even a Skylaunch, have throttles so the phrase "very

powerful
=
rapidly accelerating winch" is meaningless. Acceleration depends only on
t=
he throttle setting.

So, what could have prevented this accident?
In order of importance:

1. Faster acceleration. Get a glider airborne and climbing before a wing
c=
an drop.


Wing drop is not the cause of the problem, it is a symptom. The primary
problem is yaw and increased acceleration will exacerbate this.

2. Insist every launch have the rope exactly straight and the glider
pointe=
d exactly at the winch.

3. Better communications. Maybe someone at the launch point should have

a
=
thumb hovering over a button that lights a big, bright "EMERGENCY STOP"
sig=
n in the winch cab. Better yet, have that button trigger the guillotine.

This accident report will serve as a classroom example for many years
inclu=
ding a "can you find the screw-ups?" exercise. If you suspended the
Imperi=
al arrogance long enough, you might hear the groans and forehead slapping
f=
rom the Continent and around the world - and if you listened to what
they'r=
e saying you might start improving your miserable accident record.


Nothing like a bit of ignorance to provoke a complete misunderstanding of
reality. To a certain extent this type of accident is an operating hazard
which can be mitigated by making sure that at the very least a pilot is
immediately able to terminate the launch. To suggest that a chain of people
outside the aircraft can react in time to effect the chain of events, given
the total time over which the situation becomes irrecoverable, shows an
incredible depth of ignorance.
I have absolutely no doubt that over the years pilots in the UK have
avoided death or injury by having their hand on the release from the time
the cable is attached until complete control is gained in the launch. No,
it does not work every time, you have to actually pull it when it goes
wrong but part of the problem is that it may not be immediately apparent
that it is going wrong until it is to late for anything other than
mitigation.
The real point is that having your hand on the release may save your life,
to me that is a complete no brainer.