Actual Rope Break

[Kevin Christner]

I had my first "rope break" ever today. I was approximately 200-250ft above the ground. Emergency procedures were not a problem.

The Tost released for some reason. Its a nose hook so the back release mechanism could not have been the culprit. Further testing with the wheel break on the ground revealed no problems so I took another tow and had no problems. The ring may not have been engaged properly (doubtful) or the slack I got in the rope was just too much when it tightened back up (probable but the release still should have held).

In any case has anyone else ever experienced an actual emergency unplanned release? In 14 years of flying I have never heard of one. Good thing we do practice this.

2C

[Don Johnstone[_4_]]

At 23:20 01 June 2014, Kevin Christner wrote:
>I had my first "rope break" ever today. I was approximately 200-250ft
>abov=
>e the ground. Emergency procedures were not a problem.
>
>The Tost released for some reason. Its a nose hook so the back release
>mec=
>hanism could not have been the culprit. Further testing with the wheel
>bre=
>ak on the ground revealed no problems so I took another tow and had no
>prob=
>lems. The ring may not have been engaged properly (doubtful) or the
slack
>=
>I got in the rope was just too much when it tightened back up (probable
>but=
> the release still should have held).
>
>In any case has anyone else ever experienced an actual emergency
unplanned
>=
>release? In 14 years of flying I have never heard of one. Good thing we
>d=
>o practice this. =20
>
>2C

Most common cause is a broken spring. If the spring breaks on one side it
will still close the hook but with insufficient tension. This can cause
intermittent failures.

[Bill T]

I've had rope breaks, weak link break, with slack line during training. At altitude so not an issue.
I have had ropes part on takeoff, normally at the initial strain on the takeoff acceleration, far up the rope, so it was missed on the first rope preflight of the day and failed late in the day. The glider hade barely moved 50ft, so it was not an issue.

I've watched one ply of a three ply poly part about 50 ft in front of the glider. After I got off tow at altitude, I told the tow pilot he would need a new rope for the next tow.

If your TOST released the ring, either it was not hooked up correctly, did it rattle after hooked up?, or your TOST springs are getting weak. Time to replace it.

BillT

[JS]

Was the ring worn? If it isn't the full diameter it can self-release.
Jim

[Bill D]

On Sunday, June 1, 2014 5:20:14 PM UTC-6, Kevin Christner wrote:
> I had my first "rope break" ever today. I was approximately 200-250ft above the ground. Emergency procedures were not a problem.
>
>
>
> The Tost released for some reason. Its a nose hook so the back release mechanism could not have been the culprit. Further testing with the wheel break on the ground revealed no problems so I took another tow and had no problems. The ring may not have been engaged properly (doubtful) or the slack I got in the rope was just too much when it tightened back up (probable but the release still should have held).
>
>
>
> In any case has anyone else ever experienced an actual emergency unplanned release? In 14 years of flying I have never heard of one. Good thing we do practice this.
>
>
>
> 2C

I've had two uncommanded Tost releases myself and observed two more. (No drama ensued.) In another case, the hook wouldn't initially release until the pilot worked it loose by maneuvering the glider on tow. In all cases the release itself was found to be within its service life and in excellent condition with springs intact.

The one common thing with all these incidents was a badly worn Tost ring pair. An abrasive runway had noticeably removed metal from the small ring leaving it with a rough, pitted surface. The point of the hooks "beak" could capture the rough ring against the cage with friction even though it wasn't fully inserted into the release. Even when tested by pulling hard on the rope, it sometimes wouldn't come loose but it could still work loose during the tow. The "beak" can't capture a new, smooth ring pair.

We speculate the fail-to-release incident was the result on a worn, undersized ring getting cocked sideways inside the cage.

If the tow operator can't be convinced to replace the ring pair, have the wing runner shake the rope to make sure it rattles in the hook after it is attached. If it's captured by friction, it won't rattle.

[Tim[_10_]]

when was the release mechanism last and most recently overhauled or
replaced?
especially on old gliders teh release mechanisms were designed for the very
old and obsolete old welded
Tost double tow rings. (see the warning on Wings & Wheels website
http://www.wingsandwheels.com/page30.htm and also on TOST website) when the
current tow rings are used on these obsolete tow releases teh rings will not
completely seat in the tow release so you are always left with a partially
opened release waiting for the evental premature release...
tim

A0
"Kevin Christner" > wrote in message
...
I had my first "rope break" ever today. I was approximately 200-250ft above
the ground. Emergency procedures were not a problem.

The Tost released for some reason. Its a nose hook so the back release
mechanism could not have been the culprit. Further testing with the wheel
break on the ground revealed no problems so I took another tow and had no
problems. The ring may not have been engaged properly (doubtful) or the
slack I got in the rope was just too much when it tightened back up
(probable but the release still should have held).

In any case has anyone else ever experienced an actual emergency unplanned
release? In 14 years of flying I have never heard of one. Good thing we do
practice this.

2C

[Andrew[_13_]]

Hi Kevin

Congratulations on managing this emergency safely. A low tow
termination of the tow is a true emergency, that some people have
not managed successfully, as discussed on this website.

I've been gliding for a long time, and my experience is that
unplanned tow terminations are very rare. I have only had two
unplanned releases, the lowest at 400ft at Lasham (Euroglide 73),
the other at 1000ft at Portmoak. On the one at Lasham, I was very
aware that the entire competition grid were watching me. Both were
wave-offs, due to towplane engine problems (neither serious as it
turned out later, but the tow pilots were understandably concerned at
the time). My experience seems logical when one considers that after
liftoff, the tension on the rope should be close to the drag on the
glider, i.e. about weight divided by L/D, i.e. about 35lbs or less. Apart
from shocks from slack lines tightening, if the rope doesn't break
during the first few seconds when the glider is being dragged over
the ground, a 'pure rope break' is unlikely. The rope is essentially
'proof tested' in the first 30 seconds of every tow. I haven't had any
ring or tow-mechanism malfunctions. So from my experience, the
most likely (but rare) problem is a tow plane engine problem.

You say you are pleased that you practiced for this. I assume you
mean that you are glad you practiced 180 turns from 200ft. I wish to
say that my personal opinion is that a verbal briefing (to go straight
ahead) would have been much safer for your instructors to teach
you, with a verbal briefing that any other alternatives must be
delayed until high enough for 'some maneuvering'. I'd put that at
300ft minimum, when a 90 turn to look back, and do some thinking,
would be be ok, but even then, a turn away to the safest area should
be made, even if off-field. Otherwise, go more-or-less straight ahead,
and let the insurance company worry about their glider. I'd
recommend that instructors should teach that a low rope break is an
emergency, and the only responsibility on the pilot is to get himself
and his passenger down without harm. Damage to the glider should
not be considered. I obviously don't know for sure, but I think its
arguable that this teaching approach might produce more minor
damage to gliders, but fewer fatalities.

It's not that a typical glider isn't capable, aerodynamically-speaking,
of performing a 180 at 200ft. They obviously can. Its that an early
solo pilot may not be able to, and experienced pilots under that
stress may not be able to either.

Safety is a tricky concept. My view is that, to be safe, one should
'stop before it becomes unsafe'. That sounds obvious, but then
consider that this logically means that we should 'stop while we are
still safe'. Ie..... we should stop when we could have safely gone a bit
further. The price for safety, is to stop too early. I can remember
stopping flying (for weather) knowing people were thinking we could
have safely gone on a bit longer. And they were completely right.
Straining this logic, its arguably safer to teach to go straight ahead,
even if an excellent pilot could do a 180.

I stand by my remark made earlier, that a site where a straight-
ahead landing is likely to produce more than minor damage, is not a
safe site.


At 23:20 01 June 2014, Kevin Christner wrote:
>I had my first "rope break" ever today. I was approximately 200-
250ft
>abov=
>e the ground. Emergency procedures were not a problem.
>
>The Tost released for some reason. Its a nose hook so the back
release
>mec=
>hanism could not have been the culprit. Further testing with the
wheel
>bre=
>ak on the ground revealed no problems so I took another tow and
had no
>prob=
>lems. The ring may not have been engaged properly (doubtful) or
the slack
>=
>I got in the rope was just too much when it tightened back up
(probable
>but=
> the release still should have held).
>
>In any case has anyone else ever experienced an actual emergency
unplanned
>=
>release? In 14 years of flying I have never heard of one. Good
thing we
>d=
>o practice this. =20
>
>2C
>

[Bruce Hoult]

On Monday, June 2, 2014 4:50:10 PM UTC+12, Andrew wrote:
> My experience seems logical when one considers that after
> liftoff, the tension on the rope should be close to the drag on the
> glider, i.e. about weight divided by L/D, i.e. about 35lbs or less.

No, that's not the case unless you're not climbing.

With a tug flying at 65 knots and climbing at 6 knots (typical for our glass two seaters) somewhere around 9% of the weight of the glider (up to 600 kg or 1300 lb) is being borne by the rope. That's about 120 lbs in addition to the 35 lbs from drag.

With a 300 kg all up single seater (PW5, Libelle etc) flying a bit slower and climbing at over 1000 fpm there is actually even more strain on the rope.

I do agree that if it doesn't break on initial acceleration then it probably won't.

I'm not going to go into the turn back or not question again other than to say if you can land safely more or less straight ahead then of course do so, but you should also be competent to turn back if that's best.

[Piotr Szafranski]

Andrew,

thank you for your post. It helps to understand "why the rules are the way there are".

On Monday, June 2, 2014 6:50:10 AM UTC+2, Andrew wrote:
> Hi Kevin
>
>
>
> Congratulations on managing this emergency safely. A low tow
>
> termination of the tow is a true emergency, that some people have
>
> not managed successfully, as discussed on this website.
>
>
>
> I've been gliding for a long time, and my experience is that
>
> unplanned tow terminations are very rare. I have only had two
>
> unplanned releases, the lowest at 400ft at Lasham (Euroglide 73),
>
> the other at 1000ft at Portmoak. On the one at Lasham, I was very
>
> aware that the entire competition grid were watching me. Both were
>
> wave-offs, due to towplane engine problems (neither serious as it
>
> turned out later, but the tow pilots were understandably concerned at
>
> the time). My experience seems logical when one considers that after
>
> liftoff, the tension on the rope should be close to the drag on the
>
> glider, i.e. about weight divided by L/D, i.e. about 35lbs or less. Apart
>
> from shocks from slack lines tightening, if the rope doesn't break
>
> during the first few seconds when the glider is being dragged over
>
> the ground, a 'pure rope break' is unlikely. The rope is essentially
>
> 'proof tested' in the first 30 seconds of every tow. I haven't had any
>
> ring or tow-mechanism malfunctions. So from my experience, the
>
> most likely (but rare) problem is a tow plane engine problem.
>
>
>
> You say you are pleased that you practiced for this. I assume you
>
> mean that you are glad you practiced 180 turns from 200ft. I wish to
>
> say that my personal opinion is that a verbal briefing (to go straight
>
> ahead) would have been much safer for your instructors to teach
>
> you, with a verbal briefing that any other alternatives must be
>
> delayed until high enough for 'some maneuvering'. I'd put that at
>
> 300ft minimum, when a 90 turn to look back, and do some thinking,
>
> would be be ok, but even then, a turn away to the safest area should
>
> be made, even if off-field. Otherwise, go more-or-less straight ahead,
>
> and let the insurance company worry about their glider. I'd
>
> recommend that instructors should teach that a low rope break is an
>
> emergency, and the only responsibility on the pilot is to get himself
>
> and his passenger down without harm. Damage to the glider should
>
> not be considered. I obviously don't know for sure, but I think its
>
> arguable that this teaching approach might produce more minor
>
> damage to gliders, but fewer fatalities.
>
>
>
> It's not that a typical glider isn't capable, aerodynamically-speaking,
>
> of performing a 180 at 200ft. They obviously can. Its that an early
>
> solo pilot may not be able to, and experienced pilots under that
>
> stress may not be able to either.
>
>
>
> Safety is a tricky concept. My view is that, to be safe, one should
>
> 'stop before it becomes unsafe'. That sounds obvious, but then
>
> consider that this logically means that we should 'stop while we are
>
> still safe'. Ie..... we should stop when we could have safely gone a bit
>
> further. The price for safety, is to stop too early. I can remember
>
> stopping flying (for weather) knowing people were thinking we could
>
> have safely gone on a bit longer. And they were completely right.
>
> Straining this logic, its arguably safer to teach to go straight ahead,
>
> even if an excellent pilot could do a 180.
>
>
>
> I stand by my remark made earlier, that a site where a straight-
>
> ahead landing is likely to produce more than minor damage, is not a
>
> safe site.
>
>
>
>
>
> At 23:20 01 June 2014, Kevin Christner wrote:
>
> >I had my first "rope break" ever today. I was approximately 200-
>
> 250ft
>
> >abov=
>
> >e the ground. Emergency procedures were not a problem.
>
> >
>
> >The Tost released for some reason. Its a nose hook so the back
>
> release
>
> >mec=
>
> >hanism could not have been the culprit. Further testing with the
>
> wheel
>
> >bre=
>
> >ak on the ground revealed no problems so I took another tow and
>
> had no
>
> >prob=
>
> >lems. The ring may not have been engaged properly (doubtful) or
>
> the slack
>
> >=
>
> >I got in the rope was just too much when it tightened back up
>
> (probable
>
> >but=
>
> > the release still should have held).
>
> >
>
> >In any case has anyone else ever experienced an actual emergency
>
> unplanned
>
> >=
>
> >release? In 14 years of flying I have never heard of one. Good
>
> thing we
>
> >d=
>
> >o practice this. =20
>
> >
>
> >2C
>
> >

[Mike Oliver]

At 23:20 01 June 2014, Kevin Christner wrote:
>I had my first "rope break" ever today. I was approximately 200-250ft
>abov=
>e the ground. Emergency procedures were not a problem.
>
>The Tost released for some reason. Its a nose hook so the back release
>mec=
>hanism could not have been the culprit. Further testing with the wheel
>bre=
>ak on the ground revealed no problems so I took another tow and had no
>prob=
>lems. The ring may not have been engaged properly (doubtful) or the
slack
>=
>I got in the rope was just too much when it tightened back up (probable
>but=
> the release still should have held).
>
>In any case has anyone else ever experienced an actual emergency
unplanned
>=
>release? In 14 years of flying I have never heard of one. Good thing we
>d=
>o practice this. =20



I fly at a mainly winch launch site but perhaps fortunately originally
learnt to fly at an aero-tow site. A few years ago whilst we had a tug on
site I was giving a first ride in a Duo to a prospective syndicate partner
behind a Super Cub. As we drew level with the winch, at the far end of the
field with perhaps 300 yards of grass before a fairly high hedge, I saw the
unusual sight of the tow rope snaking towards me. I guess our height was
between 150-300 feet. I opted for a 360 degree turn and land on the grass
behind the winch. To his credit my passenger never made a sound till after
we stopped and yes he did buy a share!- The problem? The tug pilot had his
map hanging on the release cord and found it restricted his view so pulled
it off pulling the release in the process! He did buy me a beer that
evening.
>

[Kevin Christner]

> You say you are pleased that you practiced for this. I assume you
>
> mean that you are glad you practiced 180 turns from 200ft. I wish to
>
> say that my personal opinion is that a verbal briefing (to go straight
>
> ahead) would have been much safer for your instructors to teach
>
> you, with a verbal briefing that any other alternatives must be
>
> delayed until high enough for 'some maneuvering'. I'd put that at
>
> 300ft minimum, when a 90 turn to look back, and do some thinking,
>
> would be be ok, but even then, a turn away to the safest area should
>
> be made, even if off-field. Otherwise, go more-or-less straight ahead,
>
> and let the insurance company worry about their glider. I'd
>
> recommend that instructors should teach that a low rope break is an
>
> emergency, and the only responsibility on the pilot is to get himself
>
> and his passenger down without harm. Damage to the glider should
>
> not be considered. I obviously don't know for sure, but I think its
>
> arguable that this teaching approach might produce more minor
>
> damage to gliders, but fewer fatalities.
>

Hi Andrew,

Here is the US the standard instruction is that you make a 180 deg turn at or above 200ft or a straight in below 200 feet. This is what the FAA Glider Flying Handbook says.

Our site is a little tricky. The runway is parallel to a 400 foot high ridge or so. You can only make a turn to the north. Generally you should always make your turn into the wind so that the wind will cause you to drift back towards the runway. In this case I was turning away from the wind. Luckily the runway parallels a large field on the other side so if you get blown away from the runway its still possible to land in the field.

2C

[Bill D]

On Sunday, June 1, 2014 10:50:10 PM UTC-6, Andrew wrote:
> Hi Kevin
>
>
>
> Congratulations on managing this emergency safely. A low tow
>
> termination of the tow is a true emergency, that some people have
>
> not managed successfully, as discussed on this website.
>
>
>
> I've been gliding for a long time, and my experience is that
>
> unplanned tow terminations are very rare. I have only had two
>
> unplanned releases, the lowest at 400ft at Lasham (Euroglide 73),
>
> the other at 1000ft at Portmoak. On the one at Lasham, I was very
>
> aware that the entire competition grid were watching me. Both were
>
> wave-offs, due to towplane engine problems (neither serious as it
>
> turned out later, but the tow pilots were understandably concerned at
>
> the time). My experience seems logical when one considers that after
>
> liftoff, the tension on the rope should be close to the drag on the
>
> glider, i.e. about weight divided by L/D, i.e. about 35lbs or less. Apart
>
> from shocks from slack lines tightening, if the rope doesn't break
>
> during the first few seconds when the glider is being dragged over
>
> the ground, a 'pure rope break' is unlikely. The rope is essentially
>
> 'proof tested' in the first 30 seconds of every tow. I haven't had any
>
> ring or tow-mechanism malfunctions. So from my experience, the
>
> most likely (but rare) problem is a tow plane engine problem.
>
>
>
> You say you are pleased that you practiced for this. I assume you
>
> mean that you are glad you practiced 180 turns from 200ft. I wish to
>
> say that my personal opinion is that a verbal briefing (to go straight
>
> ahead) would have been much safer for your instructors to teach
>
> you, with a verbal briefing that any other alternatives must be
>
> delayed until high enough for 'some maneuvering'. I'd put that at
>
> 300ft minimum, when a 90 turn to look back, and do some thinking,
>
> would be be ok, but even then, a turn away to the safest area should
>
> be made, even if off-field. Otherwise, go more-or-less straight ahead,
>
> and let the insurance company worry about their glider. I'd
>
> recommend that instructors should teach that a low rope break is an
>
> emergency, and the only responsibility on the pilot is to get himself
>
> and his passenger down without harm. Damage to the glider should
>
> not be considered. I obviously don't know for sure, but I think its
>
> arguable that this teaching approach might produce more minor
>
> damage to gliders, but fewer fatalities.
>
>
>
> It's not that a typical glider isn't capable, aerodynamically-speaking,
>
> of performing a 180 at 200ft. They obviously can. Its that an early
>
> solo pilot may not be able to, and experienced pilots under that
>
> stress may not be able to either.
>
>
>
> Safety is a tricky concept. My view is that, to be safe, one should
>
> 'stop before it becomes unsafe'. That sounds obvious, but then
>
> consider that this logically means that we should 'stop while we are
>
> still safe'. Ie..... we should stop when we could have safely gone a bit
>
> further. The price for safety, is to stop too early. I can remember
>
> stopping flying (for weather) knowing people were thinking we could
>
> have safely gone on a bit longer. And they were completely right.
>
> Straining this logic, its arguably safer to teach to go straight ahead,
>
> even if an excellent pilot could do a 180.
>
>
>
> I stand by my remark made earlier, that a site where a straight-
>
> ahead landing is likely to produce more than minor damage, is not a
>
> safe site.
>
>
>
>
>
> At 23:20 01 June 2014, Kevin Christner wrote:
>
> >I had my first "rope break" ever today. I was approximately 200-
>
> 250ft
>
> >abov=
>
> >e the ground. Emergency procedures were not a problem.
>
> >
>
> >The Tost released for some reason. Its a nose hook so the back
>
> release
>
> >mec=
>
> >hanism could not have been the culprit. Further testing with the
>
> wheel
>
> >bre=
>
> >ak on the ground revealed no problems so I took another tow and
>
> had no
>
> >prob=
>
> >lems. The ring may not have been engaged properly (doubtful) or
>
> the slack
>
> >=
>
> >I got in the rope was just too much when it tightened back up
>
> (probable
>
> >but=
>
> > the release still should have held).
>
> >
>
> >In any case has anyone else ever experienced an actual emergency
>
> unplanned
>
> >=
>
> >release? In 14 years of flying I have never heard of one. Good
>
> thing we
>
> >d=
>
> >o practice this. =20
>
> >
>
> >2C
>
> >

The rope tension is more than the glider's weight divided by the L/D which would only be the case in level flight. Aero tow is lifting the weight of the glider into the sky which requires more tension.

The record shows premature termination of tow is far more common than you suggest. Only one incident I know of involved a rope break in the takeoff roll. The rest were rope breaks during the early airborne part of the tow.

The reason is ropes don't simply snap when overloaded. Fibers break then the rope unravels which takes a little time. If the rope was overstressed in the takeoff roll, expect it to part at few hundred feet AGL.

The 200' AGL 180 turn back to the runway is the MINIMUM STANDARD in the US. Either a pilot learns to confidently demonstrate the maneuver with grace and precision or his flying career stops right there. All pilots are expected to retain that level of ability throughout their careers and can expect to be asked to prove it in every Flight Review or Check Ride.

However, demonstrating an ability to perform the maneuver doesn't mean it's required or even the preferred action in a real emergency. It's simply an additional option in the pilots repertoire. A pilot is expected to exercise good judgment in selecting the best option for the situation.

That said, if a pilot damages a glider in a risky off field landing when the glider was in a position for a safe return to the runway, he'll likely be grounded pending a check ride.

[Dan Marotta]

At Moriarty, we create rope/ring protectors using plastic water bottles
with the bottoms cut off. The bottle is placed over the rope, large end
facing the glider, and wrapped many times with duct tape for abrasion
protection. Better to wear that out than the rings or ropes where
wrapped around the large ring.


Dan Marotta 5J

On 6/1/2014 6:45 PM, Bill D wrote:
> On Sunday, June 1, 2014 5:20:14 PM UTC-6, Kevin Christner wrote:
>> I had my first "rope break" ever today. I was approximately 200-250ft above the ground. Emergency procedures were not a problem.
>>
>>
>>
>> The Tost released for some reason. Its a nose hook so the back release mechanism could not have been the culprit. Further testing with the wheel break on the ground revealed no problems so I took another tow and had no problems. The ring may not have been engaged properly (doubtful) or the slack I got in the rope was just too much when it tightened back up (probable but the release still should have held).
>>
>>
>>
>> In any case has anyone else ever experienced an actual emergency unplanned release? In 14 years of flying I have never heard of one. Good thing we do practice this.
>>
>>
>>
>> 2C
> I've had two uncommanded Tost releases myself and observed two more. (No drama ensued.) In another case, the hook wouldn't initially release until the pilot worked it loose by maneuvering the glider on tow. In all cases the release itself was found to be within its service life and in excellent condition with springs intact.
>
> The one common thing with all these incidents was a badly worn Tost ring pair. An abrasive runway had noticeably removed metal from the small ring leaving it with a rough, pitted surface. The point of the hooks "beak" could capture the rough ring against the cage with friction even though it wasn't fully inserted into the release. Even when tested by pulling hard on the rope, it sometimes wouldn't come loose but it could still work loose during the tow. The "beak" can't capture a new, smooth ring pair.
>
> We speculate the fail-to-release incident was the result on a worn, undersized ring getting cocked sideways inside the cage.
>
> If the tow operator can't be convinced to replace the ring pair, have the wing runner shake the rope to make sure it rattles in the hook after it is attached. If it's captured by friction, it won't rattle.

[[email protected]]

Congratulations on a successful outcome Bill!

My only rope break was on my FAA check ride with an inspector in the back seat.

A turbulent tow where the line went slack. A boot full of rudder pre-tension wasn't enough apparently as *snap* a the tow rope became a flicking serpent in front of me. Approx 400ft AGL with limited options in my 12 o'clock I made a turn back and judged I was high. Deviated right of centreline to fly a short base leg to wash off excess altitude before landing. Gained a few points with the examiner that day as he had only just 're-qualifed' on gliders that morning.

In hindsight? I should have been more aggressive in the post-slack yaw to soften the blow a little more. I also feel I could have released the tow rope over the field to allow the FBO to recover the rings instead of 'systematically', soon after PTT.

As a poster in the bunkhouse says, you don't rise to the occasion, you sink to the level of your training. Thanks TK.

[[email protected]]

On Monday, 2 June 2014 23:41:10 UTC+8, wrote:
> Congratulations on a successful outcome Bill!

*ahem*

Kevin :)

[Bill D]

On Monday, June 2, 2014 9:41:10 AM UTC-6, wrote:
> Congratulations on a successful outcome Bill!
>
>
>
> My only rope break was on my FAA check ride with an inspector in the back seat.
>
>
>
> A turbulent tow where the line went slack. A boot full of rudder pre-tension wasn't enough apparently as *snap* a the tow rope became a flicking serpent in front of me. Approx 400ft AGL with limited options in my 12 o'clock I made a turn back and judged I was high. Deviated right of centreline to fly a short base leg to wash off excess altitude before landing. Gained a few points with the examiner that day as he had only just 're-qualifed' on gliders that morning.
>
>
>
> In hindsight? I should have been more aggressive in the post-slack yaw to soften the blow a little more. I also feel I could have released the tow rope over the field to allow the FBO to recover the rings instead of 'systematically', soon after PTT.
>
>
>
> As a poster in the bunkhouse says, you don't rise to the occasion, you sink to the level of your training. Thanks TK.

My first uncommanded Tost release was on a winch launch at about 10' AGL so I just landed straight ahead on the runway. This was a no-sweat event and I didn't know it was an uncommanded release until the crew told me.

The second was on aero tow just as I decided to release in a good thermal. This was more startling since it seemed like the glider had acquired some intelligence of its own.

The others were during CAP Cadet orientation rides where the Cadet attaching the rope may not have checked the security of the ring in the hook (Our fault since we hadn't trained them to do it). These incidents persuaded us to check the Tost ring pair more carefully for wear and to insist the person attaching the rope checks to insure the ring is free to rattle in the hook.

It's possible for a pilot to detect an improperly inserted ring pair since the yellow knob won't retract all the way if the ring is just "captured" by the "beak". I've learned the hard way to pay attention to how the release knob feels as the hook closes.

[Bill D]

Our tow operator uses "whiffle balls" to protect the knot and ring pair and they are almost always found inside the ball as intended so it's a bit of a mystery how they suffer so much wear.

On Monday, June 2, 2014 9:38:36 AM UTC-6, Dan Marotta wrote:
> At Moriarty, we create rope/ring protectors using plastic water bottles
>
> with the bottoms cut off. The bottle is placed over the rope, large end
>
> facing the glider, and wrapped many times with duct tape for abrasion
>
> protection. Better to wear that out than the rings or ropes where
>
> wrapped around the large ring.
>
>
>
>
>
> Dan Marotta 5J

[Don Johnstone[_4_]]

At 15:18 02 June 2014, Bill D wrote:
>On Sunday, June 1, 2014 10:50:10 PM UTC-6, Andrew wrote:
>> Hi Kevin
>>=20
>>=20
>>=20
>> Congratulations on managing this emergency safely. A low tow=20
>>=20
>> termination of the tow is a true emergency, that some people have=20
>>=20
>> not managed successfully, as discussed on this website.
>>=20
>>=20
>>=20
>> I've been gliding for a long time, and my experience is that=20
>>=20
>> unplanned tow terminations are very rare. I have only had two=20
>>=20
>> unplanned releases, the lowest at 400ft at Lasham (Euroglide 73),=20
>>=20
>> the other at 1000ft at Portmoak. On the one at Lasham, I was very=20
>>=20
>> aware that the entire competition grid were watching me. Both were=20
>>=20
>> wave-offs, due to towplane engine problems (neither serious as it=20
>>=20
>> turned out later, but the tow pilots were understandably concerned
at=20
>>=20
>> the time). My experience seems logical when one considers that after=20
>>=20
>> liftoff, the tension on the rope should be close to the drag on the=20
>>=20
>> glider, i.e. about weight divided by L/D, i.e. about 35lbs or less.
>Apart=
>=20
>>=20
>> from shocks from slack lines tightening, if the rope doesn't break=20
>>=20
>> during the first few seconds when the glider is being dragged over=20
>>=20
>> the ground, a 'pure rope break' is unlikely. The rope is essentially=20
>>=20
>> 'proof tested' in the first 30 seconds of every tow. I haven't had
any=20
>>=20
>> ring or tow-mechanism malfunctions. So from my experience, the=20
>>=20
>> most likely (but rare) problem is a tow plane engine problem.
>>=20
>> =20
>>=20
>> You say you are pleased that you practiced for this. I assume you=20
>>=20
>> mean that you are glad you practiced 180 turns from 200ft. I wish to=20
>>=20
>> say that my personal opinion is that a verbal briefing (to go
straight=20
>>=20
>> ahead) would have been much safer for your instructors to teach=20
>>=20
>> you, with a verbal briefing that any other alternatives must be=20
>>=20
>> delayed until high enough for 'some maneuvering'. I'd put that at=20
>>=20
>> 300ft minimum, when a 90 turn to look back, and do some thinking,=20
>>=20
>> would be be ok, but even then, a turn away to the safest area should=20
>>=20
>> be made, even if off-field. Otherwise, go more-or-less straight
ahead,=20
>>=20
>> and let the insurance company worry about their glider. I'd=20
>>=20
>> recommend that instructors should teach that a low rope break is an=20
>>=20
>> emergency, and the only responsibility on the pilot is to get
himself=20
>>=20
>> and his passenger down without harm. Damage to the glider should=20
>>=20
>> not be considered. I obviously don't know for sure, but I think its=20
>>=20
>> arguable that this teaching approach might produce more minor=20
>>=20
>> damage to gliders, but fewer fatalities.
>>=20
>>=20
>>=20
>> It's not that a typical glider isn't capable,
aerodynamically-speaking,=
>=20
>>=20
>> of performing a 180 at 200ft. They obviously can. Its that an early=20
>>=20
>> solo pilot may not be able to, and experienced pilots under that=20
>>=20
>> stress may not be able to either.=20
>>=20
>>=20
>>=20
>> Safety is a tricky concept. My view is that, to be safe, one should=20
>>=20
>> 'stop before it becomes unsafe'. That sounds obvious, but then=20
>>=20
>> consider that this logically means that we should 'stop while we are=20
>>=20
>> still safe'. Ie..... we should stop when we could have safely gone a
bit=
>=20
>>=20
>> further. The price for safety, is to stop too early. I can remember=20
>>=20
>> stopping flying (for weather) knowing people were thinking we could=20
>>=20
>> have safely gone on a bit longer. And they were completely right.=20
>>=20
>> Straining this logic, its arguably safer to teach to go straight
ahead,=
>=20
>>=20
>> even if an excellent pilot could do a 180.
>>=20
>>=20
>>=20
>> I stand by my remark made earlier, that a site where a straight-
>>=20
>> ahead landing is likely to produce more than minor damage, is not a=20
>>=20
>> safe site.
>>=20
>>=20
>>=20
>>=20
>>=20
>> At 23:20 01 June 2014, Kevin Christner wrote:
>>=20
>> >I had my first "rope break" ever today. I was approximately 200-
>>=20
>> 250ft
>>=20
>> >abov=3D
>>=20
>> >e the ground. Emergency procedures were not a problem.
>>=20
>> >
>>=20
>> >The Tost released for some reason. Its a nose hook so the back=20
>>=20
>> release
>>=20
>> >mec=3D
>>=20
>> >hanism could not have been the culprit. Further testing with the=20
>>=20
>> wheel
>>=20
>> >bre=3D
>>=20
>> >ak on the ground revealed no problems so I took another tow and=20
>>=20
>> had no
>>=20
>> >prob=3D
>>=20
>> >lems. The ring may not have been engaged properly (doubtful) or=20
>>=20
>> the slack
>>=20
>> >=3D
>>=20
>> >I got in the rope was just too much when it tightened back up=20
>>=20
>> (probable
>>=20
>> >but=3D
>>=20
>> > the release still should have held).
>>=20
>> >
>>=20
>> >In any case has anyone else ever experienced an actual emergency=20
>>=20
>> unplanned
>>=20
>> >=3D
>>=20
>> >release? In 14 years of flying I have never heard of one. Good=20
>>=20
>> thing we
>>=20
>> >d=3D
>>=20
>> >o practice this. =3D20
>>=20
>> >
>>=20
>> >2C
>>=20
>> >
>
>The rope tension is more than the glider's weight divided by the L/D
which
>=
>would only be the case in level flight. Aero tow is lifting the weight
of
>=
>the glider into the sky which requires more tension.
>
>The record shows premature termination of tow is far more common than you
>s=
>uggest. Only one incident I know of involved a rope break in the takeoff
>ro=
>ll. The rest were rope breaks during the early airborne part of the tow.
=
>=20
>
>The reason is ropes don't simply snap when overloaded. Fibers break then
>t=
>he rope unravels which takes a little time. If the rope was overstressed
>i=
>n the takeoff roll, expect it to part at few hundred feet AGL.
>
>The 200' AGL 180 turn back to the runway is the MINIMUM STANDARD in the
>US.=
> Either a pilot learns to confidently demonstrate the maneuver with
grace
>=
>and precision or his flying career stops right there. All pilots are
>expec=
>ted to retain that level of ability throughout their careers and can
>expect=
> to be asked to prove it in every Flight Review or Check Ride.
>
>However, demonstrating an ability to perform the maneuver doesn't mean
>it's=
> required or even the preferred action in a real emergency. It's simply
>an=
> additional option in the pilots repertoire. A pilot is expected to
>exerci=
>se good judgment in selecting the best option for the situation.
>
>That said, if a pilot damages a glider in a risky off field landing when
>th=
>e glider was in a position for a safe return to the runway, he'll likely
>be=
> grounded pending a check ride.

Bill, you need to accept that this forum is worldwide. Advice and practice
is different outside the USA. While turn backs may be de rigueur at low
height in the USA they are positively discouraged in the UK and never ever
practiced. People who make low turns receive intensive counseling and/or
remedial instruction.
I would never ever criticise a pilot, or take punitive action for choosing
the option which gives the best chance of survival. Insurance can pay for
damaged gliders, as far as I am aware all the money in the world cannot
resurrect dead people.
You have made it very clear that you feel we are lacking in some way and of
course we think the FAA is barmy, such is life.

[Kevin Christner]

Hmm I think the BGA may want to take a hard look at this. My cockpit being crushed by trees would not have been an appealing option.

> Bill, you need to accept that this forum is worldwide. Advice and practice
>
> is different outside the USA. While turn backs may be de rigueur at low
>
> height in the USA they are positively discouraged in the UK and never ever
>
> practiced. People who make low turns receive intensive counseling and/or
>
> remedial instruction.
>
> I would never ever criticise a pilot, or take punitive action for choosing
>
> the option which gives the best chance of survival. Insurance can pay for
>
> damaged gliders, as far as I am aware all the money in the world cannot
>
> resurrect dead people.
>
> You have made it very clear that you feel we are lacking in some way and of
>
> course we think the FAA is barmy, such is life.

[Bill D]

On Monday, June 2, 2014 10:38:34 AM UTC-6, Don Johnstone wrote:

"Bill, you need to accept that this forum is worldwide. Advice and practice
is different outside the USA."

Don, you need to accept that it's different everywhere outside the UK.

"While turn backs may be de rigueur at low height in the USA."

Wrong. Turns are optional. TRAINING is de regueur.

"You have made it very clear that you feel we are lacking in some way."

In very specific ways.

"We think the FAA is barmy."

Thanks for pointing that out. I've made sure they got the message.

[[email protected]]

I didn't have and actual rope break but had a PTT in 1997. I had about 110 hrs in gliders and was flying an ASW 15B. It was my second flight in that particular glider. The release occured at about 500 ft AGL and I was able to make and abbreviated circuit and land back at the take off Runway 14 at Dansville, NY. Thanks to excellent trainig at the Finger Lkkes Soaring Club, it was not unexpected or very dramatic. The PTT was due to an improper tow ring that someone had put on the tow rope. It was not a Tost Ring Set. I learned to look carefully at the tow ring set before hook up. This resulted in a cleanup of all the improper tow rings in the club. Lets see, 17 years ago, am I due for another one soon? I'm ready!

Chuck Zabinski
N839CZ

[Bill D]

On Sunday, June 1, 2014 5:20:14 PM UTC-6, Kevin Christner wrote:
> I had my first "rope break" ever today. I was approximately 200-250ft above the ground. Emergency procedures were not a problem.
>
>
>
> The Tost released for some reason. Its a nose hook so the back release mechanism could not have been the culprit. Further testing with the wheel break on the ground revealed no problems so I took another tow and had no problems. The ring may not have been engaged properly (doubtful) or the slack I got in the rope was just too much when it tightened back up (probable but the release still should have held).
>
>
>
> In any case has anyone else ever experienced an actual emergency unplanned release? In 14 years of flying I have never heard of one. Good thing we do practice this.
>
>
>
> 2C

I think it's worth inserting in this thread that the Germans suffer essentially zero aero tow PT3 accidents. The US could do the same by strictly observing FAR 91.309, FAR 91.9 and OSHA CFR 1915.112 on rope working strength where life is at risk as well as the Tost specifications on ring pair wear limits. The US and German regulations are essentially the same.

It works like this. Start by using a weak link at the glider as required by the glider flight manual (FAR 91.9) and a weak link 25% stronger at the tug (FAR 91.309) then use a rope 8x as strong as the strongest weak link (CFR 1915.112).

AFAIK, the strongest aero tow weak link called out in a glider manual is 2,436 Lbs-F (LAK-20) so CFR 1915.112 would require a rope with at least 19,500 Lb-F breaking strength. 3/8" Amsteel Blue from Sampson Rope would just meet this requirement. http://www.samsonrope.com/Pages/Product.aspx?ProductID=872

This rope would be much more expensive than what is commonly used now but it would last much longer - and the lives it would save would be priceless. Rope breaks would be a thing of the past.

A possible argument against Amsteel Blue is its very light weight so rope slack might float above the glider risking entanglement. This could be overcome by using a urethane rope coating as is used on helicopter slings to make the rope heavier and far more abrasion resistant. With a urethane coating, the rope should last decades.

I know someone will point out that a Schweizer hook is limited to 1,200 Lbs-F so it's impossible to comply with 91.9 and 91.309 using this hook. Yep, that's what it means. It IS possible to comply using the Tost tow plane hook.

[[email protected]]

On Sunday, June 1, 2014 7:20:14 PM UTC-4, Kevin Christner wrote:
> I had my first "rope break" ever today. I was approximately 200-250ft above the ground. Emergency procedures were not a problem.
>
>
>
> The Tost released for some reason. Its a nose hook so the back release mechanism could not have been the culprit. Further testing with the wheel break on the ground revealed no problems so I took another tow and had no problems. The ring may not have been engaged properly (doubtful) or the slack I got in the rope was just too much when it tightened back up (probable but the release still should have held).
>
>
>
> In any case has anyone else ever experienced an actual emergency unplanned release? In 14 years of flying I have never heard of one. Good thing we do practice this.
>
>
>
> 2C

Kevin,

I had my first (and hopefully only) one with full water ballast 200 ft, windy conditions at Perry a couple of years ago. I was the first glider on the grid, and managed to get it back down safely, without running into the other 61 gliders on the grid! The line crew immediately turned me around and launched again, even before I had a chance to clean out my underwear ;-).

Frank (TA)

[Steve Leonard[_2_]]

On Monday, June 2, 2014 4:08:14 PM UTC-5, Bill D wrote:
"I know someone will point out that a Schweizer hook is limited to 1,200 Lbs-F so it's impossible to comply with 91.9 and 91.309 using this hook. Yep, that's what it means. It IS possible to comply using the Tost tow plane hook."

Only flaw in that logic, Bill, is that the HOOK may be approved for that load, but the AIRPLANE it is attached to may NOT be approved for that load. Sort of like how on that old TV show "The Six Million Dollar Man", he could pick up the multi-thousand pound rock with his bionic arm, but they ignored the fact that his still human spine couldn't take the load and he would have been crushed.

I agree with you 100% that there are better things out there than Schweizer tow hitches. But, you can't suddenly legally pull 2000 lbs on the back end of your Cessna or Piper just because your tow hitch is now good for that much load. You have to know where the weakest link is, and either not exceed its limit, or you must increase the strength of it.

As to reliability, I have never known a Schwiezer release to let go of the still intact ring because the ring was worn. I have known of worn Schweizer releases releasing without pilot command, just like a Tost can do if the ring is worn, possibly beyond its allowed limits. So, neither one is perfect. If you have a choice as to which you want to use, make your decision and be willing to listen to the opinions of others.

Interesting that this thread is called "Actual Rope Break" when the rope in question doesn't appear to have broken? :-) We now return to our regularly scheduled programming...

Steve Leonard

[Bill D]

On Tuesday, June 3, 2014 8:01:50 AM UTC-6, Steve Leonard wrote:
> On Monday, June 2, 2014 4:08:14 PM UTC-5, Bill D wrote:
>
> "I know someone will point out that a Schweizer hook is limited to 1,200 Lbs-F so it's impossible to comply with 91.9 and 91.309 using this hook. Yep, that's what it means. It IS possible to comply using the Tost tow plane hook."
>
>
>
> Only flaw in that logic, Bill, is that the HOOK may be approved for that load, but the AIRPLANE it is attached to may NOT be approved for that load. Sort of like how on that old TV show "The Six Million Dollar Man", he could pick up the multi-thousand pound rock with his bionic arm, but they ignored the fact that his still human spine couldn't take the load and he would have been crushed.
>
>
>
> I agree with you 100% that there are better things out there than Schweizer tow hitches. But, you can't suddenly legally pull 2000 lbs on the back end of your Cessna or Piper just because your tow hitch is now good for that much load. You have to know where the weakest link is, and either not exceed its limit, or you must increase the strength of it.
>
>
>
> As to reliability, I have never known a Schwiezer release to let go of the still intact ring because the ring was worn. I have known of worn Schweizer releases releasing without pilot command, just like a Tost can do if the ring is worn, possibly beyond its allowed limits. So, neither one is perfect. If you have a choice as to which you want to use, make your decision and be willing to listen to the opinions of others.
>
>
>
> Interesting that this thread is called "Actual Rope Break" when the rope in question doesn't appear to have broken? :-) We now return to our regularly scheduled programming...
>
>
>
> Steve Leonard

Steve, you have a point. My defense is that the installation of a Tost tow plane hook requires an STC which, one presumes, would take aircraft structure into consideration. The Tost Hook itself is approved for 2,570 Lbs-F. If the aircraft structure is weaker, the STC should state a lower limit.

Most composite 2-seater flight manuals (Grob 103, ASK-21 etc...) call out a 600 daN blue weak link for aero tow so the tow plane link would be a red 750 daN link (1,686 Lbs-F) That's more than a Schweizer hook could take but much less than the Tost.

[Bill D]

On Tuesday, June 3, 2014 8:01:50 AM UTC-6, Steve Leonard wrote:
> On Monday, June 2, 2014 4:08:14 PM UTC-5, Bill D wrote:
>
> "I know someone will point out that a Schweizer hook is limited to 1,200 Lbs-F so it's impossible to comply with 91.9 and 91.309 using this hook. Yep, that's what it means. It IS possible to comply using the Tost tow plane hook."
>
>
>
> Only flaw in that logic, Bill, is that the HOOK may be approved for that load, but the AIRPLANE it is attached to may NOT be approved for that load. Sort of like how on that old TV show "The Six Million Dollar Man", he could pick up the multi-thousand pound rock with his bionic arm, but they ignored the fact that his still human spine couldn't take the load and he would have been crushed.
>
>
>
> I agree with you 100% that there are better things out there than Schweizer tow hitches. But, you can't suddenly legally pull 2000 lbs on the back end of your Cessna or Piper just because your tow hitch is now good for that much load. You have to know where the weakest link is, and either not exceed its limit, or you must increase the strength of it.
>
>
>
> As to reliability, I have never known a Schwiezer release to let go of the still intact ring because the ring was worn. I have known of worn Schweizer releases releasing without pilot command, just like a Tost can do if the ring is worn, possibly beyond its allowed limits. So, neither one is perfect. If you have a choice as to which you want to use, make your decision and be willing to listen to the opinions of others.
>
>
>
> Interesting that this thread is called "Actual Rope Break" when the rope in question doesn't appear to have broken? :-) We now return to our regularly scheduled programming...
>
>
>
> Steve Leonard

Thinking about this a bit more, a bigger problem is tow planes which are only approved for use with the Schweizer hook. Ex: Cessna 182's. Technically, they are only legal when towing gliders with a 965 Lb-F (439 daN) or less weak link which would exclude composite 2-seaters. FAR 91.9 trumps FAR 91.309 if the glider's Approved flight Manual contains an aero tow weak link specification.

[Andrew[_13_]]

Hi Bruce

thank you for noting there is extra tension in the aerorow rope due
to the angle of climb. If the climb rate is 3kts (which is typical for a
2-seater at my club) at a towing speed of 60kts, the angle of climb
(theta) = 3/60 radians = 3 degrees, and the extra tension in the
rope is (weight of glider)*(sin theta) = typically 1000*(sin 3
degrees) = 50lbs. This would add to the tension in the rope due to
glider drag, as you say, to make a typical aerotow rope tension of
35+50 = 85lbs.

My estimate of the tension in the aerotow rope during initial
ground roll, assuming acceleration of a 1000lb glider to 60kts in
10secs, is about 315lbs.

Whilst the numbers can be juggled for different sailplanes and
towplanes, I agree with you that the greatest rope tension is likely
to be during initial acceleration i.e. during the ground roll. So
aerotow ropes are 'proof tested' on every ground roll, to a useful
degree. This does not assure that the rope meets the full rated
breaking strain however.

I read Bill's comment of June 2 about the rope perhaps taking
some longer time to actually break. This is a new idea to me, and I
don't know what too make of it. I'd like to hear the evidence for
this effect.

The more important discussion, is whether it is a good idea to train
or teach 200ft turn-backs to our students. Despite it being long
accepted practice, in the USA anyway, I doubt that it is a good idea
in terms of reducing serious accident rates. I note nobody suggests
we teach students to do final turns under 200ft. I wonder why.

I was interested in the suggestion from others that Germany has a
much lower PT3 accident rate, due to their stronger ropes and
weak links, and that this could perhaps be allowed by the FAA.


At 07:04 02 June 2014, Bruce Hoult wrote:
>On Monday, June 2, 2014 4:50:10 PM UTC+12, Andrew wrote:
>> My experience seems logical when one considers that after
>> liftoff, the tension on the rope should be close to the drag on
the
>> glider, i.e. about weight divided by L/D, i.e. about 35lbs or less.
>
>No, that's not the case unless you're not climbing.
>
>With a tug flying at 65 knots and climbing at 6 knots (typical for
our
>glass two seaters) somewhere around 9% of the weight of the
glider (up to
>600 kg or 1300 lb) is being borne by the rope. That's about 120
lbs in
>addition to the 35 lbs from drag.
>
>With a 300 kg all up single seater (PW5, Libelle etc) flying a bit
slower
>and climbing at over 1000 fpm there is actually even more strain
on the
>rope.
>
>I do agree that if it doesn't break on initial acceleration then it
>probably won't.
>
>I'm not going to go into the turn back or not question again other
than to
>say if you can land safely more or less straight ahead then of
course do
>so, but you should also be competent to turn back if that's best.
>
>

[Bruce Hoult]

On Wednesday, June 4, 2014 2:17:46 PM UTC+12, Andrew wrote:
> I note nobody suggests we teach students to do final turns
> under 200ft. I wonder why.

I believe we train students to try to manage the circuit to aim to make the turn to final at about 300 ft, depending on how close in they are.

If they get it wrong (or hit sink) and find themselves at 200 ft instead, I don't think anyone is going to advise them not to make the turn!


If you were *planning* to make the final turn at 200 ft (which would be perfectly safe) but actually ended up the same 100 ft lower then that's getting very low indeed.


Finding yourself *actually* at 200 ft is not the same thing as planning to be at 200 ft at some point in the future with a chance that you might be higher or lower.

[Bill D]

Reasonable questions, Andrew. I'll try to answer some of them to a degree below.

On Tuesday, June 3, 2014 8:17:46 PM UTC-6, Andrew wrote:
> Hi Bruce
>
>
>
> thank you for noting there is extra tension in the aerorow rope due
>
> to the angle of climb. If the climb rate is 3kts (which is typical for a
>
> 2-seater at my club) at a towing speed of 60kts, the angle of climb
>
> (theta) = 3/60 radians = 3 degrees, and the extra tension in the
>
> rope is (weight of glider)*(sin theta) = typically 1000*(sin 3
>
> degrees) = 50lbs. This would add to the tension in the rope due to
>
> glider drag, as you say, to make a typical aerotow rope tension of
>
> 35+50 = 85lbs.
>
> My estimate of the tension in the aerotow rope during initial
>
> ground roll, assuming acceleration of a 1000lb glider to 60kts in
>
> 10secs, is about 315lbs.
-----------------------------
The European certification standards under CS-22 mentions the aero tow rope tension designers should expect. I seem to recall that number is 150daN. That would be close to your estimate.
-----------------------------
>
> Whilst the numbers can be juggled for different sailplanes and
>
> towplanes, I agree with you that the greatest rope tension is likely
>
> to be during initial acceleration i.e. during the ground roll. So
>
> aerotow ropes are 'proof tested' on every ground roll, to a useful
>
> degree. This does not assure that the rope meets the full rated
>
> breaking strain however.
>
-------------------
I suspect the loads encountered in slack recovery could be the greatest.
-------------------

>
> I read Bill's comment of June 2 about the rope perhaps taking
>
> some longer time to actually break. This is a new idea to me, and I
>
> don't know what too make of it. I'd like to hear the evidence for
>
> this effect.
------------------
There are lots of engineering papers on rope testing and failure modes available on the Internet. The basic idea is a rope is a large bundle of twisted fibers. Not all those individual fibers are equal in strength nor are they loaded equally. When it gets overloaded some of those fibers reach their breaking point before others and the rope starts to unravel.

The unraveling process is usually spotted when the rope is inspected but sometimes it progresses fast enough for the rope to fail before it gets inspected. In almost all cases there is a time interval between fiber breakage and catastrophic failure, otherwise rope inspections wouldn't work.

All but a couple of the rope breaks I know of happened after lift off and below about 1500 feet with normal tension on the rope.
------------------
>
> The more important discussion, is whether it is a good idea to train
>
> or teach 200ft turn-backs to our students. Despite it being long
>
> accepted practice, in the USA anyway, I doubt that it is a good idea
>
> in terms of reducing serious accident rates. I note nobody suggests
>
> we teach students to do final turns under 200ft. I wonder why.
>
----------------
This one is easy. A turn to final is a normal operating procedure not an emergency like a rope break recovery. There's no justification for practicing low turns to final. A rope break is a true emergency so the rule book can be disregarded as far as necessary to deal with it safely.

I think there are enough stories, some related here, to say lives have been saved and injuries avoided when pilots returned to the runway after a rope break. I can't recall any training accidents practicing the return-to-runway maneuver but there may be a few. I've done hundreds and don't recall sweating out one of them.
----------------
>
> I was interested in the suggestion from others that Germany has a
>
> much lower PT3 accident rate, due to their stronger ropes and
>
> weak links, and that this could perhaps be allowed by the FAA.
>
----------------------
This is the ultimate solution - just eliminate rope breaks altogether by using a rope so strong it's hard to imagine it breaking. However, weak links could still break so I would continue the training.

It's not so much the US government "allows" stronger weak links and rope - the Federal Air Regulations and Occupational Safety and Health Administration rules require it. It's just that we haven't been following those rules.

[Kevin Christner]

> This one is easy. A turn to final is a normal operating procedure not an emergency like a rope break recovery. There's no justification for practicing low turns to final.

Here I think I would disagree with you. In a number of land out situations (small fields) turning final at lower than 200ft would be preferable as it would increase the chance of safely landing in the field.

[Bill D]

On Wednesday, June 4, 2014 9:36:13 AM UTC-6, Kevin Christner wrote:
> > This one is easy. A turn to final is a normal operating procedure not an emergency like a rope break recovery. There's no justification for practicing low turns to final.
>
>
>
> Here I think I would disagree with you. In a number of land out situations (small fields) turning final at lower than 200ft would be preferable as it would increase the chance of safely landing in the field.

I don't follow you. How does a low turn increase the chance of landing safely? Wouldn't a standard sized pattern with a higher turn followed by a longer final approach work as well?