Actual Rope Break

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

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.

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

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

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.

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

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

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.

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

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.