Winch Launch Fatality

On Jun 24, 10:45*am, Del C wrote:
I knew that agreeing with Bill Daniels was too good to last!

Given a vaguely competent pilot, the most likely cause of a wing drop is a
gust, especially if there is a cross-wind component. That is what happened
in the series of photos that show a K13 standing on it's starboard
wingtip. I put a link into this in an earlier posting. Please note that
full opposite aileron and rudder is being applied throughout this
incident!

On the subject of not accidentally pulling the release knob as a result of
holding it, you need to arrange the cockpit so you are not holding the
release at full stretch.

Some glass single seaters are very good at hiding the release knob almost
out of reach somewhere below your crutch and behind the stick. On my own
glider I have extended the cable so it is easier to reach the knob (with
the approval of a BGA Inspector I hasten to add).

The last fatal cartwheel accident in the UK involved an ASW20L glider. If
you read the aaib report, they concluded that once the stick was hard over
to the left, which it would have been as it was the right wing that
dropped, it would have been almost impossible to get to the release knob
if you weren't holding it already!

Derek Copeland

At 15:29 24 June 2009, bildan wrote:

On Jun 23, 5:42=A0pm, Andy *wrote:
On Jun 23, 4:18=A0pm, ucsdcpc *wrote:

have a look at the simulation videos on the BGA website

http://www.gliding.co.uk/bgainfo/saf...nch-safety.htm

you don't have a lot of time to find the release knob if a wing
drops

Maybe not, but it's hard to believe the wing drop simulations are
representative. =A0What reasonably trained pilots would stuff the wing
into the ground and then continue to hold full aileron into the low
wing? =A0It would be interesting to see the same scenario simulated
with
an external upset causing the wing drop and full recovery aileron
being applied at and after wing tip contact. =A0Throw in various
amounts
of drag on the low wing tip to simulate short grass, long grass, etc
and then introduce pilot release before, at, and after wing tip
contact, and I'd start to believe it was a useful training aid.

Andy

It's realistic in the sense that the most likely way a wing would go
down is if the pilot does, in fact, "stuff it down". *Unfortunately,
you just have to watch a few takeoffs to see it happen. *One of my
frustrations is pilots who seem to have no idea where their ailerons
are until a wingtip hits the ground.

If the pilot consciously centers the ailerons as part of the pre-
takeoff checks and lets the wing runner balance the glider, the glider
will just stay balanced on its own for several seconds after the wing
runner lets go *- long enough to get aileron control on either aero
tow or winch. *That's good practice with any launch method.

What I see in that K-13 sequence is the parachute disappearing off the
left side of the frame after it was released. It gives the appearance
the glider was staged at least 30 degrees off the line of sight to the
winch. I also don't see any aileron or rudder applied in the first
frame with the wing on the ground indicating the pilot was WAAY behind
the glider.

Blaming this 100% on a gust seems a reach.

Once a wing drops onto the ground, the glider will almost inevitably veer
off in the same direction due to ground friction, which is what you see
here and what you also see in my video of a wing drop. The photographer
didn't quite catch the start of this incident, and I am sure that the
glider would have been lined up correctly.

The wing tip runner for the K13 was a very experienced pilot and an ex
syndicate partner of mine. He told me that it was a cold, windy and very
blustery day and that none of our runways lined up with the wind
direction, so there was about a 30 degree cross wind from the right. The
chain of events started with a violent gust that caused the wing to drop
as he let go. The instructor tried to pull off, but his gloved hand
slipped round the round release knob, twice in fact. He was successful at
the third attempt, but reported that it took a lot more force than he
expected to release under tension. By this time he was airborne, so had to
take over and fight the glider back onto the ground somehow. What was
interesting was the the eventual landing direction was at right angles to
the start direction, once the rudder was taken off. The student pilot may
not have dealt with the dropping wing very well, but there is no evidence
that he contributed to it.

After this incident, our CFI wanted to fit T handle releases to our K13s,
but EASA said no because it counted as a major modification and would
require full design approval (very expensive). Bureaucracy gone mad or
what!

Derek Copeland


At 18:54 24 June 2009, bildan wrote:
What I see in that K-13 sequence is the parachute disappearing off the
left side of the frame after it was released. It gives the appearance
the glider was staged at least 30 degrees off the line of sight to the
winch. I also don't see any aileron or rudder applied in the first
frame with the wing on the ground indicating the pilot was WAAY behind
the glider.

Blaming this 100% on a gust seems a reach.

What is particularly interesting in both the video and the photographs is
the direction the glider is pointing relative to the cable. In the video
the glider can be seen to yaw as the cable tightens and then further yaw
as the it starts to move.
In the photographs it is clear that the glider is pointing to the right of
the direction of the cable AND stangely is pointed in the same direction as
the K13 parked behind it, a co-incidence perhaps. In both cases it would
appear possible that the glider was not lined up with the cable prior to
launch so that as soon as the cable moved yaw was induced. With a CofG
hook the glider will be more unstable about the yaw axis than was the case
with the more forward release on older gliders. Perhaps that might explain
why this appears to be a "new" phenomenon.


At 21:45 24 June 2009, Derek Copeland wrote:
Once a wing drops onto the ground, the glider will almost inevitably
veer
off in the same direction due to ground friction, which is what you see
here and what you also see in my video of a wing drop. The photographer
didn't quite catch the start of this incident, and I am sure that the
glider would have been lined up correctly.

The wing tip runner for the K13 was a very experienced pilot and an ex
syndicate partner of mine. He told me that it was a cold, windy and very
blustery day and that none of our runways lined up with the wind
direction, so there was about a 30 degree cross wind from the right. The
chain of events started with a violent gust that caused the wing to drop
as he let go. The instructor tried to pull off, but his gloved hand
slipped round the round release knob, twice in fact. He was successful
at
the third attempt, but reported that it took a lot more force than he
expected to release under tension. By this time he was airborne, so had
to
take over and fight the glider back onto the ground somehow. What was
interesting was the the eventual landing direction was at right angles
to
the start direction, once the rudder was taken off. The student pilot
may
not have dealt with the dropping wing very well, but there is no
evidence
that he contributed to it.

After this incident, our CFI wanted to fit T handle releases to our
K13s,
but EASA said no because it counted as a major modification and would
require full design approval (very expensive). Bureaucracy gone mad or
what!

Derek Copeland


At 18:54 24 June 2009, bildan wrote:
What I see in that K-13 sequence is the parachute disappearing off the
left side of the frame after it was released. It gives the appearance
the glider was staged at least 30 degrees off the line of sight to the
winch. I also don't see any aileron or rudder applied in the first
frame with the wing on the ground indicating the pilot was WAAY behind
the glider.

Blaming this 100% on a gust seems a reach.

The apparent cable offset was because we were using a retrieve winch.
However the cable always pulled approximately straight under tension as
the launch commenced. It was normal to place the launch queue on the
downwind side of the retrieve winch, so that any slight weather-cocking at
the start of the launch if anything further reduced the angle between the
cable and the glider, and also reduced the possibility of the wind getting
under the upwind wing. The gliders would have been set up to point at the
main winch, or just slightly upwind of it to reduce any yaw at the start.


IMHO the use of a retrieve winch actually reduces the possibility of a
wing drop, and was not a factor in either case. Particularly in the video,
the glider was running straight before the wing drop occured, and was
probably due to the student pilot failing to do anything positive to keep
the wings level in a slight cross wind from the right, plus a late
take-over by a very newly qualified (at the time) instructor.

Derek Copeland


At 01:00 25 June 2009, Don Johnstone wrote:
What is particularly interesting in both the video and the photographs
is
the direction the glider is pointing relative to the cable. In the video
the glider can be seen to yaw as the cable tightens and then further yaw
as the it starts to move.
In the photographs it is clear that the glider is pointing to the right
of
the direction of the cable AND stangely is pointed in the same direction
as
the K13 parked behind it, a co-incidence perhaps. In both cases it would
appear possible that the glider was not lined up with the cable prior to
launch so that as soon as the cable moved yaw was induced. With a CofG
hook the glider will be more unstable about the yaw axis than was the
case
with the more forward release on older gliders. Perhaps that might
explain
why this appears to be a "new" phenomenon.


At 21:45 24 June 2009, Derek Copeland wrote:
Once a wing drops onto the ground, the glider will almost inevitably
veer
off in the same direction due to ground friction, which is what you see
here and what you also see in my video of a wing drop. The photographer
didn't quite catch the start of this incident, and I am sure that the
glider would have been lined up correctly.

The wing tip runner for the K13 was a very experienced pilot and an ex
syndicate partner of mine. He told me that it was a cold, windy and
very
blustery day and that none of our runways lined up with the wind
direction, so there was about a 30 degree cross wind from the right.
The
chain of events started with a violent gust that caused the wing to
drop
as he let go. The instructor tried to pull off, but his gloved hand
slipped round the round release knob, twice in fact. He was successful
at
the third attempt, but reported that it took a lot more force than he
expected to release under tension. By this time he was airborne, so had
to
take over and fight the glider back onto the ground somehow. What was
interesting was the the eventual landing direction was at right angles
to
the start direction, once the rudder was taken off. The student pilot
may
not have dealt with the dropping wing very well, but there is no
evidence
that he contributed to it.

After this incident, our CFI wanted to fit T handle releases to our
K13s,
but EASA said no because it counted as a major modification and would
require full design approval (very expensive). Bureaucracy gone mad or
what!

Derek Copeland


At 18:54 24 June 2009, bildan wrote:
What I see in that K-13 sequence is the parachute disappearing off
the
left side of the frame after it was released. It gives the appearance
the glider was staged at least 30 degrees off the line of sight to the
winch. I also don't see any aileron or rudder applied in the first
frame with the wing on the ground indicating the pilot was WAAY behind
the glider.

Blaming this 100% on a gust seems a reach.

On Jun 24, 7:00*pm, Don Johnstone wrote:
What is particularly interesting in both the video and the photographs is
the direction the glider is pointing relative to the cable. In the video
the glider can be seen to yaw as the cable tightens and then further yaw
as the it starts to move.
In the photographs it is clear that the glider is pointing to the right of
the direction of the cable AND stangely is pointed in the same direction as
the K13 parked behind it, a co-incidence perhaps. In both cases it would
appear possible that the glider was not lined up with the cable prior to
launch so that as soon as the cable moved yaw was induced. With a CofG
hook the glider will be more unstable about the yaw axis than was the case
with the more forward release on older gliders. Perhaps that might explain
why this appears to be a "new" phenomenon.

Nope, they lined it up at an angle to the wire then all the other
stuff compounded the problem. There are other videos from Lasham with
the gliders improperly staged which show a similar wobbly takeoff. If
the gilder isn't pointing at the winch, the takeoff will be
'interesting'. Unfortunately, some people in the US are showing the
k-13 photo sequence as proof that winches are too dangerous to use.
This actually forced me to add a paragraph in my winch training
syllabus cautioning pilots to aim gliders at the winch - which any kid
launching a balsa glider with a rubber band would understand without
being told.

To be fair, there very well could have been a wind event that we, in a
dustier climate, would call a "dust devil" which couldn't be seen in
lush green England. We would see it coming and stand down until the
thing passed - then launch and go chase it for the lift it marks.

For Christs sake Bill! Lasham is the largest and most professional gliding
club in the UK and we do about 10,000 winch launches per year, 9,999 of
which go without incident. We do know what we are doing. We either point
the glide directly at the main winch, or just slightly upwind of it in a
crosswind to reduce any initial yaw due to weather cocking.

The K13 incident was caused by a gust, and the glider was landed without
damage or injury. A similar wing drop during an aerotow would be
considered quite unremarkable. The correct thing to do is to pull off if a
wing drops during a winch launch.

Derek Copeland

At 03:42 26 June 2009, bildan wrote:
On Jun 24, 7:00=A0pm, Don Johnstone wrote:
What is particularly interesting in both the video and the photographs
is
the direction the glider is pointing relative to the cable. In the
video
the glider can be seen to yaw as the cable tightens and then further
yaw
as the it starts to move.
In the photographs it is clear that the glider is pointing to the
right
o=
f
the direction of the cable AND stangely is pointed in the same
direction
=
as
the K13 parked behind it, a co-incidence perhaps. In both cases it
would
appear possible that the glider was not lined up with the cable prior
to
launch so that as soon as the cable moved yaw was induced. With a CofG
hook the glider will be more unstable about the yaw axis than was the
cas=
e
with the more forward release on older gliders. Perhaps that might
explai=
n
why this appears to be a "new" phenomenon.

Nope, they lined it up at an angle to the wire then all the other
stuff compounded the problem. There are other videos from Lasham with
the gliders improperly staged which show a similar wobbly takeoff. If
the gilder isn't pointing at the winch, the takeoff will be
'interesting'. Unfortunately, some people in the US are showing the
k-13 photo sequence as proof that winches are too dangerous to use.
This actually forced me to add a paragraph in my winch training
syllabus cautioning pilots to aim gliders at the winch - which any kid
launching a balsa glider with a rubber band would understand without
being told.

To be fair, there very well could have been a wind event that we, in a
dustier climate, would call a "dust devil" which couldn't be seen in
lush green England. We would see it coming and stand down until the
thing passed - then launch and go chase it for the lift it marks.

You should not necessarily point the glider at the winch, you should point
it in the direction that the cable is going to take. If there is a bow in
the cable then the glider should not point at the winch but towards the
bow so that yaw is not induced.
Of course the ideal and proper situation is that the cable runs straight
from the winch to the takeoff point when the cable direction and the winch
are both in the same direction.

The correct thing to do if a wing drops is to release the cable, semantics
maybe but can we please get the terminology right at least.

Just to illustrate the point many years a go a gliding site in the UK
winch launched on a dog leg, the winch cable changed direction halfway
down the run by being taken round a telegraph pole and the launch was
always towards the pole. The change in direction when the cable reached
the top of the pole and slipped off was interesting, the good news was
that CofG hooks were not common so the pull of the cable helped to damp
the yaw induced. I would not want to do it in a modern glider with a CofG
hook, damm dangerous I would think.



At 07:30 26 June 2009, Derek Copeland wrote:
For Christs sake Bill! Lasham is the largest and most professional
gliding
club in the UK and we do about 10,000 winch launches per year, 9,999 of
which go without incident. We do know what we are doing. We either point
the glide directly at the main winch, or just slightly upwind of it in a
crosswind to reduce any initial yaw due to weather cocking.

The K13 incident was caused by a gust, and the glider was landed without
damage or injury. A similar wing drop during an aerotow would be
considered quite unremarkable. The correct thing to do is to pull off if
a
wing drops during a winch launch.

Derek Copeland

At 03:42 26 June 2009, bildan wrote:
On Jun 24, 7:00=A0pm, Don Johnstone wrote:
What is particularly interesting in both the video and the
photographs
is
the direction the glider is pointing relative to the cable. In the
video
the glider can be seen to yaw as the cable tightens and then further
yaw
as the it starts to move.
In the photographs it is clear that the glider is pointing to the
right
o=
f
the direction of the cable AND stangely is pointed in the same
direction
=
as
the K13 parked behind it, a co-incidence perhaps. In both cases it
would
appear possible that the glider was not lined up with the cable prior
to
launch so that as soon as the cable moved yaw was induced. With a
CofG
hook the glider will be more unstable about the yaw axis than was the
cas=
e
with the more forward release on older gliders. Perhaps that might
explai=
n
why this appears to be a "new" phenomenon.

Nope, they lined it up at an angle to the wire then all the other
stuff compounded the problem. There are other videos from Lasham with
the gliders improperly staged which show a similar wobbly takeoff. If
the gilder isn't pointing at the winch, the takeoff will be
'interesting'. Unfortunately, some people in the US are showing the
k-13 photo sequence as proof that winches are too dangerous to use.
This actually forced me to add a paragraph in my winch training
syllabus cautioning pilots to aim gliders at the winch - which any kid
launching a balsa glider with a rubber band would understand without
being told.

To be fair, there very well could have been a wind event that we, in a
dustier climate, would call a "dust devil" which couldn't be seen in
lush green England. We would see it coming and stand down until the
thing passed - then launch and go chase it for the lift it marks.

On Jun 26, 10:30*am, Don Johnstone wrote:
You should not necessarily point the glider at the winch, you should point
it in the direction that the cable is going to take. If there is a bow in
the cable then the glider should not point at the winch but towards the
bow so that yaw is not induced.

A typical answer for a steel cable user. Steel digs in to the ground
as it is puled out. You don't know if a steel cable will maintain its
initial direction or 'twang' back to center jerking the glider around.

UHMWPE/Dyneema rope will take a dead straight line from the glider to
the winch as it is tensioned. The stuff is so light that it easily
skips sideways over weeds and grass. If it fails to straighten out,
it's likely caught on something solid and you'd best investigate.

Yet another reason to dump steel cable.

On 26 June, 17:30, Don Johnstone wrote:
You should not necessarily point the glider at the winch, you should point
it in the direction that the cable is going to take. If there is a bow in
the cable then the glider should not point at the winch but towards the
bow so that yaw is not induced.
Of course the ideal and proper situation is that the cable runs straight
from the winch to the takeoff point when the cable direction and the winch
are both in the same direction.

The correct thing to do if a wing drops is to release the cable, semantics
maybe but can we please get the terminology right at least.

Just to illustrate the point many years a go a gliding site in the UK
winch launched on a dog leg, the winch cable changed direction halfway
down the run by being taken round a telegraph pole and the launch was
always towards the pole. The change in direction when the cable reached
the top of the pole and slipped off was interesting, the good news was
that CofG hooks were not common so the pull of the cable helped to damp
the yaw induced. I would not want to do it in a modern glider with a CofG
hook, damm dangerous I would think.

Don,

You are clearly referring to the Scottish Gliding Union at Portmoak
airfield where I have been member since 1977. We continued launching
on the dogleg ash strip for many years after that including many
gliders with C of G hooks with no problem at all (including, in my
case over those years, K6E, Diamant, Std Cirrus, Kestrel 19, Nimbus
2C). The point that is is relevant to the "where to point the glider"
issues is this: Waiting for a launch we lined up one behind the other
straight down the strip with the cable coming straight into the
glider. We were therefore pointing well to one side of the winch but
the gliders took off perfectly straight down the strip. I was never
particularly aware of any direction change during the launch.

Now that we launch straight towards the winch on the main grass parts
of the airfield we have more, not less, issues with gliders being
swung by the cable and that is because the gliders queue side by side
with a gap between them for the cable retrieve vehicle to pass
through. For each glider the cable has to be pulled over to the
glider leaving a bow in the last 50m or so of the cable. A steel
cable being pulled through grass by a our lowish power winch does
*not* pull straight as the slack is taken up and can easily swing the
glider right at the start of the ground run. When I launch I always
insist the last 50m of cable is pulled as straight as possible and not
just that the drogue chute is pulled to the front of the glider. If
that were not possible I would agree that the glider should more or
less line up with the closest 50m of cable when launching off grass.
When launching from a hard runway (or our old ash strip) this is much
less of an issue because the cable can slip sideways over the ground
so much more easily.

John Galloway