Glider accident while filming commercial in 2011. NTSB Report updated

On Wednesday, June 26, 2013 3:38:21 PM UTC-6, Paul Ruskin wrote:
Hi Bill

So, Andreas verifies the 5 accidents the BFU lists for 2011 was all there was in 900,000 winch launches.



http://rdd.me/dstznowe says the UK suffered 12 for 180,000 launches.



How does that stack up?

UK: 1:15,000

Germany 1:180,000

Seems like Germany has a 12:1 lower accident rate.



Actually, the reference you quote above says that in 2011 there were 12 accidents plus incidents. Not the same as accidents. It's not really credible that the accident rate is 12:1 but the fatality / serious rate roughly the same, as calculated earlier. I think we're going to need to agree to differ on this one though.



It's great that the safer winch launching initiative in the UK has improved things but I think you need to find out what the Germans are doing right. I'd start by watching every "windenstart" video on YouTube. Hint: Time the takeoff rolls



OK - good thought. So I did. First five UK launches 5,2,2,4,2 seconds (roughly). First five German ones 5,4,3,3,2. Again roughly. Not a lot of difference (caveat - not a large sample and dependent on lots of other things). What was interesting was that the first two UK ones were from the same club, and used their old and new winch respectively. I think this time is largely equipment driven - could be that newer winches tend to be higher power. Don't disagree in principle though - and as I mentioned earlier, avoiding wing drop is a current focus at the moment in the UK.



On your point about minimum winch airspeed, I agree totally. It's standard teaching: (BGA Instructors' manual edition 3 page 16-1). I find it strange that gliders are placarded with maximum airspeed but not minimum.



Paul

When timing takeoff rolls, you need to find a way to consistently pick a moment when the acceleration begins. Many of the launches roll for several meters before the winch driver really hits the throttle. I choose the moment a nose wheel/skid glider's tail goes down and for tail wheel gliders when the wing runner lets go to start the clock.

To compensate a bit for this late clock start, I stop the clock when the glider's wheel is .5 - 1m above the ground. It's not perfect but then it's YouTube.

It's also necessary to estimate the wind. If there's a lot of wind noise on the sound track or the trees are obviously bending, I disregard that video. If I can see a wind sock in the background, I can estimate the wind. If there's a good sound track without wind noise, there's probably little wind.

Try that and see if your numbers change.

The following short clip is taken from a video made for ESPN back in the 90s
some time. This is how it should have looked:
http://www.youtube.com/watch?v=DHa-t...ature=youtu.be


"Bill D" wrote in message
...
On Wednesday, June 26, 2013 3:38:21 PM UTC-6, Paul Ruskin wrote:
Hi Bill

So, Andreas verifies the 5 accidents the BFU lists for 2011 was all
there was in 900,000 winch launches.



http://rdd.me/dstznowe says the UK suffered 12 for 180,000 launches.



How does that stack up?

UK: 1:15,000

Germany 1:180,000

Seems like Germany has a 12:1 lower accident rate.



Actually, the reference you quote above says that in 2011 there were 12
accidents plus incidents. Not the same as accidents. It's not really
credible that the accident rate is 12:1 but the fatality / serious rate
roughly the same, as calculated earlier. I think we're going to need to
agree to differ on this one though.



It's great that the safer winch launching initiative in the UK has
improved things but I think you need to find out what the Germans are
doing right. I'd start by watching every "windenstart" video on YouTube.
Hint: Time the takeoff rolls



OK - good thought. So I did. First five UK launches 5,2,2,4,2 seconds
(roughly). First five German ones 5,4,3,3,2. Again roughly. Not a lot
of difference (caveat - not a large sample and dependent on lots of other
things). What was interesting was that the first two UK ones were from
the same club, and used their old and new winch respectively. I think
this time is largely equipment driven - could be that newer winches tend
to be higher power. Don't disagree in principle though - and as I
mentioned earlier, avoiding wing drop is a current focus at the moment in
the UK.



On your point about minimum winch airspeed, I agree totally. It's
standard teaching: (BGA Instructors' manual edition 3 page 16-1). I find
it strange that gliders are placarded with maximum airspeed but not
minimum.



Paul

When timing takeoff rolls, you need to find a way to consistently pick a
moment when the acceleration begins. Many of the launches roll for several
meters before the winch driver really hits the throttle. I choose the
moment a nose wheel/skid glider's tail goes down and for tail wheel gliders
when the wing runner lets go to start the clock.

To compensate a bit for this late clock start, I stop the clock when the
glider's wheel is .5 - 1m above the ground. It's not perfect but then it's
YouTube.

It's also necessary to estimate the wind. If there's a lot of wind noise on
the sound track or the trees are obviously bending, I disregard that video.
If I can see a wind sock in the background, I can estimate the wind. If
there's a good sound track without wind noise, there's probably little wind.

Try that and see if your numbers change.

On Wednesday, June 26, 2013 2:40:30 PM UTC-6, Martin Gregorie wrote:

the past I've used a stopwatch and timed consistent launches as taking 5 secs from first movement until the glider started to rotate into full climb, which I assumed meant the glider was accelerating through 50 kts.

This corresponds to roughly 0.5G on average.

That's about the same result I got from UK videos. The German "windenstart" videos seem to average 1.0G (19kts/sec)acceleration. I've yet to read of an accident that can be unequivocally attributed to excessive acceleration.

Indeed.

As an example - the BGA statistics include any accident or incident
reported by a member anywhere in the world. So their numbers include
locations in Spain and South Africa.

The German numbers do not.

I express no opinion on which is a better approach. Merely that the one
is organisational statistics and the other is geographic.

Bruce

On 2013/06/26 11:38 PM, Paul Ruskin wrote:
Hi Bill
So, Andreas verifies the 5 accidents the BFU lists for 2011 was all there was in 900,000 winch launches.

http://rdd.me/dstznowe says the UK suffered 12 for 180,000 launches.

How does that stack up?
UK: 1:15,000
Germany 1:180,000
Seems like Germany has a 12:1 lower accident rate.

Actually, the reference you quote above says that in 2011 there were 12 accidents plus incidents. Not the same as accidents. It's not really credible that the accident rate is 12:1 but the fatality / serious rate roughly the same, as calculated earlier. I think we're going to need to agree to differ on this one though.

It's great that the safer winch launching initiative in the UK has improved things but I think you need to find out what the Germans are doing right. I'd start by watching every "windenstart" video on YouTube. Hint: Time the takeoff rolls

OK - good thought. So I did. First five UK launches 5,2,2,4,2 seconds (roughly). First five German ones 5,4,3,3,2. Again roughly. Not a lot of difference (caveat - not a large sample and dependent on lots of other things). What was interesting was that the first two UK ones were from the same club, and used their old and new winch respectively. I think this time is largely equipment driven - could be that newer winches tend to be higher power. Don't disagree in principle though - and as I mentioned earlier, avoiding wing drop is a current focus at the moment in the UK.

On your point about minimum winch airspeed, I agree totally. It's standard teaching: (BGA Instructors' manual edition 3 page 16-1). I find it strange that gliders are placarded with maximum airspeed but not minimum.

Paul


--
Bruce Greeff
T59D #1771

On Friday, June 28, 2013 1:56:50 AM UTC-6, BruceGreeff wrote:
Indeed.



As an example - the BGA statistics include any accident or incident

reported by a member anywhere in the world. So their numbers include

locations in Spain and South Africa.



The German numbers do not.



I express no opinion on which is a better approach. Merely that the one

is organisational statistics and the other is geographic.



Bruce



On 2013/06/26 11:38 PM, Paul Ruskin wrote:

Hi Bill

So, Andreas verifies the 5 accidents the BFU lists for 2011 was all there was in 900,000 winch launches.



http://rdd.me/dstznowe says the UK suffered 12 for 180,000 launches.



How does that stack up?

UK: 1:15,000

Germany 1:180,000

Seems like Germany has a 12:1 lower accident rate.



Actually, the reference you quote above says that in 2011 there were 12 accidents plus incidents. Not the same as accidents. It's not really credible that the accident rate is 12:1 but the fatality / serious rate roughly the same, as calculated earlier. I think we're going to need to agree to differ on this one though.



It's great that the safer winch launching initiative in the UK has improved things but I think you need to find out what the Germans are doing right. I'd start by watching every "windenstart" video on YouTube. Hint: Time the takeoff rolls



OK - good thought. So I did. First five UK launches 5,2,2,4,2 seconds (roughly). First five German ones 5,4,3,3,2. Again roughly. Not a lot of difference (caveat - not a large sample and dependent on lots of other things). What was interesting was that the first two UK ones were from the same club, and used their old and new winch respectively. I think this time is largely equipment driven - could be that newer winches tend to be higher power. Don't disagree in principle though - and as I mentioned earlier, avoiding wing drop is a current focus at the moment in the UK.



On your point about minimum winch airspeed, I agree totally. It's standard teaching: (BGA Instructors' manual edition 3 page 16-1). I find it strange that gliders are placarded with maximum airspeed but not minimum.



Paul





--

Bruce Greeff

T59D #1771

Not correct. The Germans do report accidents anywhere in the world.

On Thursday, 27 June 2013 16:28:40 UTC+1, Bill D wrote:
On Wednesday, June 26, 2013 2:40:30 PM UTC-6, Martin Gregorie wrote:



the past I've used a stopwatch and timed consistent launches as taking 5 secs from first movement until the glider started to rotate into full climb, which I assumed meant the glider was accelerating through 50 kts.



This corresponds to roughly 0.5G on average.



That's about the same result I got from UK videos. The German "windenstart" videos seem to average 1.0G (19kts/sec)acceleration. I've yet to read of an accident that can be unequivocally attributed to excessive acceleration.

================================================== ===========================

Having been winch launching since 1969 I find myself disagreeing that very rapid accelaration at the beginning of the ground run is necessarily a good thing. Being off the ground in 2-3 seconds means (approximately) going from 0-60mph in that time and which gives a rate of increase of energy into the system such that if a wing does drop then and catch then there is little chance of the pilot preventing what should have been a release +/- groundloop turning into a cartwheel/flick tragedy. 1 g acceleration means that the glider is pulled off the ground so fast that it is unlikely to drop a wing but increases the chance of disaster if it does.

We lost the pilot of a Nimbus 3 to a cartwheel accident at our club last year. The accident report not yet published so I am not saying this was a factor there but it is self evident that if a glider pilot can release the cable in time before a wingtip hits the ground then there would be zero chance of a cartwheel accident

Furthermore excessive acceleration can cause some glider types to rotate too fast in that rate of rotation can increse the stall speed at this critical time.

The BGA advice for powerful winches is 3 seconds to the intended maximum intended (not necessarily full) thottle position for the glider and winch type - with the engine rpm following a bit behind that - and that feels right to me.

See the BGA winch operations slide show at:

http://www.gliding.co.uk/bgainfo/saf.../winchops.ppsx

John Galloway

On Friday, June 28, 2013 11:50:30 AM UTC-6, wrote:
On Thursday, 27 June 2013 16:28:40 UTC+1, Bill D wrote:

On Wednesday, June 26, 2013 2:40:30 PM UTC-6, Martin Gregorie wrote:







the past I've used a stopwatch and timed consistent launches as taking 5 secs from first movement until the glider started to rotate into full climb, which I assumed meant the glider was accelerating through 50 kts.







This corresponds to roughly 0.5G on average.







That's about the same result I got from UK videos. The German "windenstart" videos seem to average 1.0G (19kts/sec)acceleration. I've yet to read of an accident that can be unequivocally attributed to excessive acceleration.



================================================== ===========================



Having been winch launching since 1969 I find myself disagreeing that very rapid accelaration at the beginning of the ground run is necessarily a good thing. Being off the ground in 2-3 seconds means (approximately) going from 0-60mph in that time and which gives a rate of increase of energy into the system such that if a wing does drop then and catch then there is little chance of the pilot preventing what should have been a release +/- groundloop turning into a cartwheel/flick tragedy. 1 g acceleration means that the glider is pulled off the ground so fast that it is unlikely to drop a wing but increases the chance of disaster if it does.



We lost the pilot of a Nimbus 3 to a cartwheel accident at our club last year. The accident report not yet published so I am not saying this was a factor there but it is self evident that if a glider pilot can release the cable in time before a wingtip hits the ground then there would be zero chance of a cartwheel accident



Furthermore excessive acceleration can cause some glider types to rotate too fast in that rate of rotation can increse the stall speed at this critical time.



The BGA advice for powerful winches is 3 seconds to the intended maximum intended (not necessarily full) thottle position for the glider and winch type - with the engine rpm following a bit behind that - and that feels right to me.



See the BGA winch operations slide show at:



http://www.gliding.co.uk/bgainfo/saf.../winchops.ppsx



John Galloway

You and the BGA are tragically wrong. You need to take another long look at that analysis. Slow acceleration is the most significant cause of the poor UK accident record. Dragging a glider along with the pilot struggling for aileron control is not conducive to winch safety.

The safest possible acceleration would get the glider away from the ground instantly, but a 1G, 2-second ground roll is safe and practical. 1G acceleration winch launches are well proven in Germany to be safer. (It also happens to be the same as that felt when laying on one's back.)

On Friday, June 28, 2013 11:50:30 AM UTC-6, wrote:

Furthermore excessive acceleration can cause some glider types to rotate too fast in that rate of rotation can increse the stall speed at this critical time.


This is waaay over rated. Pick any glider you think is vulnerable and I'm sure there's a video on the Internet of it being launched with less than a 2-second ground roll. Acceleration alone does not cause uncommanded pitch-up.

Is an inertial-couple induced pitch-up real? Yes. But it can't happen with a tailwheel in contact with the runway and the pilot can oppose it with down elevator above the 50 knots Vw-min. That leaves the 40 to 50 knot window lasting 1/2 second at 1G acceleration where a glider's natural rotational inertia about the pitch axis and it's aerodynamic stability will prevent excessive pitch-up.

What CAN go wrong is if the pilot gets impatient with a slow acceleration and pulls up in the window of vulnerability so the inertial couple combines with up elevator to produce an excessive pitch-up. There are dozens of videos showing UK pilots doing exactly that on YouTube. The cure is simple - teach pilot to hold the nose down and wait for Vw-min before allowing the glider to rotate into a climb.

On Friday, June 28, 2013 1:04:12 PM UTC-6, Bill D wrote:
On Friday, June 28, 2013 11:50:30 AM UTC-6, wrote:

On Thursday, 27 June 2013 16:28:40 UTC+1, Bill D wrote:



On Wednesday, June 26, 2013 2:40:30 PM UTC-6, Martin Gregorie wrote:















the past I've used a stopwatch and timed consistent launches as taking 5 secs from first movement until the glider started to rotate into full climb, which I assumed meant the glider was accelerating through 50 kts.















This corresponds to roughly 0.5G on average.















That's about the same result I got from UK videos. The German "windenstart" videos seem to average 1.0G (19kts/sec)acceleration. I've yet to read of an accident that can be unequivocally attributed to excessive acceleration.







================================================== ===========================







Having been winch launching since 1969 I find myself disagreeing that very rapid accelaration at the beginning of the ground run is necessarily a good thing. Being off the ground in 2-3 seconds means (approximately) going from 0-60mph in that time and which gives a rate of increase of energy into the system such that if a wing does drop then and catch then there is little chance of the pilot preventing what should have been a release +/- groundloop turning into a cartwheel/flick tragedy. 1 g acceleration means that the glider is pulled off the ground so fast that it is unlikely to drop a wing but increases the chance of disaster if it does.







We lost the pilot of a Nimbus 3 to a cartwheel accident at our club last year. The accident report not yet published so I am not saying this was a factor there but it is self evident that if a glider pilot can release the cable in time before a wingtip hits the ground then there would be zero chance of a cartwheel accident







Furthermore excessive acceleration can cause some glider types to rotate too fast in that rate of rotation can increse the stall speed at this critical time.







The BGA advice for powerful winches is 3 seconds to the intended maximum intended (not necessarily full) thottle position for the glider and winch type - with the engine rpm following a bit behind that - and that feels right to me.







See the BGA winch operations slide show at:







http://www.gliding.co.uk/bgainfo/saf.../winchops.ppsx







John Galloway



You and the BGA are tragically wrong. You need to take another long look at that analysis. Slow acceleration is the most significant cause of the poor UK accident record. Dragging a glider along with the pilot struggling for aileron control is not conducive to winch safety.

This is what I'm talking about:
http://www.youtube.com/watch?v=Ls_VIfxOV8U

Slow acceleration CAUSES accidents.

On Fri, 28 Jun 2013 09:56:50 +0200, BruceGreeff
wrote:

Indeed.

As an example - the BGA statistics include any accident or incident
reported by a member anywhere in the world. So their numbers include
locations in Spain and South Africa.

The German numbers do not.

I express no opinion on which is a better approach. Merely that the one
is organisational statistics and the other is geographic.

HI Bruce,

German accident statistics include any accident/incident that happened
on a German airfield, in Germany, or in which a German registered
aircraft was involved, worldwide.


Cheers
Andreas