[Bill Cummings]

Quote by Charlie---
“ It also does well used in conjunction with an AT dolly (all due deference
to your opinion of the contraptions as only a regular PT harness is used).”

BC replies---
Charlie,
I have used an AT dolly while static towing behind my car on a dirt airstrip.

I used the Skyting Bridle (2/1) when dolly launching.
I’m not clear on how you all are hooking up to the pilot so I thought I should caution you if you are towing from the pilot only with the towline passing below the base tube. Or even above the base tube.

I personally would not tow up like that since I would be at the mercy of the tow vehicle. If the winch should bind up and not pay out line I could find myself climbing too fast with the nose pitched up to where I could not get the nose down. That scenario will increase the line tension to the point of popping the weaklink, nose high, and close to the ground. Hooking to the pilot only with the towline under the base tube is only suitable for Platform Launching.

Some drivers have been taught to quickly run out in front of the pilot and get some line out so that the pilot is being pulled more forward and not so much down.
I see this as not being the best procedure. Low angles of tow need a climb restricting bridle to the keel otherwise a situation can arise where being towed too fast will have you helplessly unable to get the nose down with weight shift alone.

A pilot has complete pitch control while PL towing only if the pilot maintains as close to a 30 to 50 degree angle behind the PL rig.

[MikeLake]

Quote by Charlie---
“ It also does well used in conjunction with an AT dolly (all due deference
to your opinion of the contraptions as only a regular PT harness is used).”

BC replies---
Charlie,
I have used an AT dolly while static towing behind my car on a dirt airstrip.

I used the Skyting Bridle (2/1) when dolly launching.
I’m not clear on how you all are hooking up to the pilot so I thought I should caution you if you are towing from the pilot only with the towline passing below the base tube. Or even above the base tube.

I personally would not tow up like that since I would be at the mercy of the tow vehicle. If the winch should bind up and not pay out line I could find myself climbing too fast with the nose pitched up to where I could not get the nose down. That scenario will increase the line tension to the point of popping the weaklink, nose high, and close to the ground. Hooking to the pilot only with the towline under the base tube is only suitable for Platform Launching.

Some drivers have been taught to quickly run out in front of the pilot and get some line out so that the pilot is being pulled more forward and not so much down.
I see this as not being the best procedure. Low angles of tow need a climb restricting bridle to the keel otherwise a situation can arise where being towed too fast will have you helplessly unable to get the nose down with weight shift alone.

A pilot has complete pitch control while PL towing only if the pilot maintains as close to a 30 to 50 degree angle behind the PL rig.

Hi Bill,
I hope you don't mind me chiming in here.

It is true a 2 point bridle (pilot + glider) makes it much easier to keep the nose down but not immune to the pitch up, detach, stall scenario.
Given enough thrust the glider has little option but to raise its angle relative to the horizon and gusty thermic conditions are likely to raise it momentarily still further, despite the pilots actions.

Unfortunately 'enough thrust' is well within the bounds of the tensions we normally tow at (100kg for and average pilot over here. You?).

Given that you can reduce but not eliminate this problem every take off is a bit of a lottery (admittedly with reasonably good odds) if you move the weak-link value too close to the tow tensions normally experienced.
It is refreshing to see that you do at least recognise that in some instances a weak-link break could be a problem and is a bit more then a 'non even' some head in sand 'experts' would have us all believe.

Sorry if this is opening up a can of worms.

[Bill Cummings]

31.7 Kilogram = 70 Pounds (about)
56.7 Kilograms =125 Pounds (about)
100 Kilogram = 220.5 Pounds (about)
158.8 Kilogram = 350 pounds (about)

Hey Mike,
Good to see you here!
I use 160 Kg as my highest value weaklink for payout towing with a winch/reel with too much rope on it.
Depending on the winch/reel like my High Perspective made in Canada I have used just short of 1100 Meters of 4.8mm of Poly-Pro diamond braid.
4.7625mm = 0.1875 inch which we call here in the USA 3/16”
(I hope that’s correct because my math sucks and speling is my only strong point.)
Anyway, that big winch/reel is able to handle 1100 Meters of 4.7625 mm of line without have too much “nesting,” burying, or sinking into the remaining wraps of rope around the winch/reel.

Other smaller sized winch/reels that also have 1100 Meters of line has a lot of nesting that has caused me to up my weaklink strength to my personal maximum of about 160 Kilograms. This makes for non smooth payout and much line abrasion.
Most of the operations here use about 56.7 Kilograms or 125 Pounds of tow force for winch payout platform towing.

Without a payout winch/reel, static towing (ST) my weaklink of choice is 99.8 Kilograms saying it our wrong USA way would be about 220 Pounds.

On Hadley Robinsons stationary hydraulic winch I can use a weaklink as low as 31.75 Kilograms which said improperly here would be 70 Pounds. His winch does not pull above that value.

I have never had a weaklink break that caused me to climb into a stall after stuffing the bar.
As soon as it broke I stuff the bar and it continues to fly.

QUOTE Mike: “Sorry if this is opening up a can of worms.”
No problem. Is there any Ketchup with that?
I had been working on another post about weaklinks that I will post next.
Check it out below ---This is how you open a can of worms.

[Bill Cummings]

The weak-link sleeping dog has been hashed out on other forums akin to whipping a dead horse. Some moderators have even lock down threads about weak-links rather than go stark raving mad.

Forget the endless argument over what weak-links are for.
Simplify it down to what they do.
Tow--or--break.

Forget what releases are for.
Simplify it down to what they do.
Release--or--fail to release.

First this: Tow--or--break.
If a weak-link breaks and it puts you at risk due to loss of towing tension what was your plan B, for when the towline failed? For when the release broke apart? For when something went through the aero-tugs prop and it disintegrated? For when the tow vehicle ran out of gas? For when an internal muffler baffle broke off inside and plugged the aero-tows muffler exhaust, killing the motor? (Hopefully nothing else.)
For when the tug’s throttle cable broke? For when the oil injector failed and the motor seized? For when the tug pilot bumped the choke lever and flooded the motor? For when a deer or kid ran out in front of the platform truck? For when dirt got into the fuel and killed the motor? For when the spark plug fouled?
HAD ENOUGH? No? Okay then -- to continue, what was plan B, for when the tugs joystick control cable broke on the tug? For when the tug couldn’t clear the trees and dumped the towline? For when the tow trucks coil burned out? For when a tow vehicle tire blew out? For when the tugs front wheel fork snapped and dug into the dirt before lift off?
OH ---OH--
Here is one you’ll like: A friend had his chest safety belt come unhooked from the lap buckle and the chest belt went into the prop killed the Rotax engine and destroyed the prop.
I know other motor heads out there are reading this and haven’t yet read here what happened to them. Feel free to reply and expand the list of other stuff that can reduce thrust that wasn’t planned.

The point here is if you are being towed into the air and not expecting that at any second you will be able to handle the loss of tow tension, YOU ARE DOING SOMETHING WRONG!

Example. The contest launch director signaled the tug to start the tow. There is a two to three mile per hour tail wind. You’re comfortable that your weak-link will not break because you are using a strong-weak-link. The (Lord help me--) strong weak-link will get you safely to altitude so that you would have enough room to turn into the wind to land should it become necessary. The last thing you want to do is give up your, “next up,” position and go the back of the line with your launch dolly to eliminate the tailwind launch.
But let’s be real here. Will the stronger weak-link also protect you from all those other thrust killing events that we just went over and others that we haven‘t even brought up?
It is times like these that you have to recognize that, YOU ARE DOING SOMETHING WRONG! (Pop Quiz. In this case what was it?)

Does the thought of your weak-link breaking make you uncomfortable? It shouldn’t.

When I/we static tow (ST) with a car or truck we use 1,600’ of towline.
We tow not to the end of the tow road but 3/10 of a mile short of the end. After we dropped the line the car will slowly drive to the end. That will allow our dropped end to be pulled out of the side field and back up onto the road. All this while the weak-link would be getting roughed up for 3/10 of a mile.
We would release the car end and go back to attach to the pilots’ end and pull it back to the next pilot. So we would never reuse a weak-link.
Since it was a one time use we often would troll down the tow road for thermals. If we were approaching the 3/10th of a mile end point and before we got there and having not yet hooked a thermal we would, “Milk the weak-link.” We would see how much extra altitude we could get before the weak-link broke or we arrived at the 3/10 of a mile end point.

The strongest weak-link that we ever used was 350 lbs (1.6 times our all up weight.) for payout winch/reel.
For static we use 220 lbs for a weak-link. Neither of these two breaking limits would cause any control problems when they broke. (Of course you have to pull the bar in when the weak-link broke or the hang glider will climb, drop airspeed and stall.)

Nothing takes all the fear out of a weak-link breaking than doing it on purpose during the many static tows that you do. You develop a feel for when they are about to break. It even helps when towing into a thermal low. You know when to get the nose down to save your weak-link so that you can continue to top out.


Release--or fail to release.
I can’t agree with the following statement that I have heard from several sources in the past that goes something like this--
The statement:
I no more expect my release to fail than I do my hang strap.

I don’t think releases are as reliable as a hang strap for the following reasons.

I’ve used just about every release known to the sport of hang gliding with the exception of the chest mounted KOCH and a Tost release.
I’ve noticed that even this Tost release had several theories involved for the failure with similar applications that are recorded at the sailplane website. It is quite possible that the hang gliding use and the sailplane use have nothing at all in common. I have no experience with any type of chest mounted KOCH or Tost release.
https://groups.google.com/forum/#!topic ... qkM7QyKc8I

http://www.tost.de/Eindex.html

This is not going to be an in depth investigation into the reasons that all releases that I have used to date have failed. If I believed for one second that my hang strap was equally as reliable as the best release out there I would not fly again. What I do is adopt a procedure that has, built into it, allowances for the few chances of a release failure.

Why? Because I’ve had a few too many release failures.

On the other hand if my hang strap had failed with the same regularity as my release failures you would not be reading this.
I was really excited years back to read up on the Link-Knife development and ordered several. Finally, a release that was even fool proof. (Or at least to those less of one than me.)

The first failure was when the release after having been dragged through the snow, which filled up the plastic tube, then froze solid at altitude. Pulling the release cord just shook and bowed the towline a little.

The second failure was slushy snow on the “O” ring. At altitude it froze to the plastic tube and prevented the “O” ring from moving which prevented the weak-link string from coming in contact with the two internal razor blades.
Pulling the release cord just shook and bowed the towline a little.

The third failure (not the fault of the release) was using some twisted poly-pro., towline instead of diamond braid poly-pro 3/16 inch.
Under tension the rope untwisted about three to five times which wrapped the Skyting Bridle up about three to five times and captured the release cord between the keel rope and the body ropes to the pilot. Pulling the release cord just shook and bowed the towline a little.

The fourth failure was during mid summer on what we referred to as Gene’s Field. Gene Stone found it. A piece of straw somehow got into the slot of the Link-knife and shielded the weak-link string from the two razor blades. Pulling the release cord just shook and bowed the towline a little.

I’ve had threaded bridles capture in the process of unthreading after releasing.

I’ve had straight pin barrel releases fail to release.

I’ve had curved pin barrel releases fail to release.

Which by the way I hope everyone has seen the picture that Jim Rooney put up on the OZ report about accidentally rigging up a curved pin barrel release backwards so that it will not release once the barrel is pulled back. I find it unbelievable that this failure to release didn’t also happen to me. I must be getting luckier.

I’ll spare you the other release failures and captures.
I’m able to post this because I never towed with a weak-link --- that wasn’t!!
I’m not going to waste my time worrying about a weak-link that might break.
I’ll save the worry for when it doesn’t.
If you are of the opinion that the weak-link is only there to protect the hang glider and you are using a tow line with the same strength as 3/16 poly., rope then why not eliminate the weak-link completely? 3/16 poly towline will never break a hang glider in the air.

Some pilots may think this last suggestion about removing the weak-link sounds stupid but that’s only because they’re correct.

If you haven’t hooked up your towing bridle and weak-link between two vehicles (car or truck) and slowly pulled the weak-link to destruction to see what will happen ---YOU ARE DOING SOMETHING WRONG!

If a tow pilot hasn’t had a release failure or a capture upon releasing -- you will.
There is a far, far, lesser chance of a hang strap failure.

Earlier you read that you should have a plan “B” for when you lost tow tension since there are many more possible causes than a weak-link break. (Again motor heads please feel free to reply to this post with other thrust killing experiences not yet covered that you heard or know about.)

Now what is the plan, “B” for a release failure, for example, while aero-towing? Jim Rooney over on the OZ Report weak-link thread said something to the effect that a pilot could push out and pop the weak-link to get free of tow. (Paraphrased and not verbatim.)
Jim and I are on the same page with respect to weak-links.

My personal plan, “B” for when my release fails will be of no use to the pilots
found in the camp of, “Strong Weak-Links. (oxymoron.)

Pilots in this camp are precluded from applying my plan, “B” so we have to move quickly to plan, “C.”
The problem here is that I have never personally had to move beyond my plan, “B,” to my plan, “C,” Parachute (four feet off of the dolly?---yeah r-r-r-i-i-ght.) “D,” Prayer, and last on the list, --- hook knife. (With the exception of one point attachment while platform towing which may work.)
(I have at times had several redundant back up releases.)

I fully expect that cutting a towing bridle or towline (static tow, platform or dolly tow) near the ground would pose the ultimate test exercise for any “Focused Pilot.”

My plan “B” after a failed release attempt is first to break the weak-link on purpose.

[Bob Kuczewski]

Great can of worms!!!!

I like the comparison between a release and a hang strap. That really drives home the point.

As forum moderator, I try to read every post on the forum. I know Tad has long pushed the "strong weak link" idea, and I'm glad to see the other side of the argument being presented.

I also like that this discussion emphasizes that breaking a weak link is something that can be practiced - just like we practice stalls - so we understand how to handle them and to not be afraid of them. I had a terrifying stall experience with my instructor when I was learning to fly airplanes back in the 70s. For a long time I feared getting close to stall. As long as I feared stalls, I was not spending much time getting comfortable with them, and that didn't make me a better pilot. So there's a lot to be said for safely learning to handle the inevitable rather than trying to come up with some way to avoid the inevitable.

Nice job Bill !!!!       

[Bob Kuczewski]

As another suggestion, I think the notions of balance and pilot choice should be introduced at some point. The curve of injuries as a function of weak link strength probably looks something like this:

weak_link_0001s.png (17.56 KiB) Viewed 5099 times

That means there's danger on either end ... and even at the lowest (best) possible point!!

However, the shape of that curve for any particular pilot is based on their choice of equipment, conditions, and their own pilot skill. A pilot with good skills at recovering from weak link breaks (as Bill mentioned above) will be operating with a curve that's much lower (less chance of injury) on the left side than a pilot with poor skills at recovering from weak link breaks. Similarly, a pilot using a good quality release will be operating with a curve that's lower on the right side than a pilot using a poor release.

In the end, I think the best weak link strength will be based on the combination of equipment, conditions, and pilot skill. So one of the goals of this chapter should be to show the full range of those issues so the individual pilot can be educated as to how to weigh them in making their own choice of weak link strength. It's important to remember that the safest weak link strength may differ between two pilots even if they have the same weight, equipment, and conditions. Their skills matter, and I think that is very well said in Bill's post.

Great topic and discussions Bill, Sam, Mike, and Charlie!!!

[MikeLake]

Hi All,

Sorry I haven't spent too much time tidying this up as I’m looking after my two granddaughters and both are rather fond of granddad’s ‘taptop’. If you spot something like degree when I mean disagree then blame my spell checker for not knowing what I meant to say!!

There are several contentious issues here but for now I’d like to concentrate on just a few.

Just to understand where I’m coming from and to get a consistent frame of reference I am assuming.

A system with an observer, a winch-man able to control tension, reduce power and in extreme situations guillotine the line.

A system with automatic tension control. Something able to make a reasonable effort at keeping line tensions within preset limits. Fixed line I avoid and consider dangerous.

To keep things simple I’m the pilot and without an endless runway I need about 100kg of thrust to get to a reasonable height more than this and I’m uncomfortable, much less makes for lousy height gains.

First and foremost I disagree strongly that a pilot is always able to fly their way out of an unplanned line separation. Furthermore I say that this mentality is positively dangerous.
Removing 100kg of thrust changes the flying mode from one of climbing under power to one of free flight with an abnormal nose up attitude in an instant, this is a fact.
A pilot in a similar situation on his landing approach would consider himself in an extremely uncomfortable situation to say the least.

A good pilot should indeed be prepared for such an unplanned line separation (along with many other situations he might encounter during a launch). However, I have seen enough evidence to convince me that this is not always the case. There are situations that even perfect pilots cannot deal with and, it is a fact, most pilots are not perfect indeed by definition most pilots are only average.
Also conditions are not always perfect enough to allow for the textbook recovery technique to work as desired. (pulling in hard with a bit of a wing up for example.)
When I say line separation I include all the things that might go wrong such as a line break, premature release and the like, fortunately these are rare events and tow groups do all that is possible to avoid them. A (too weak) weak-link on the other hand is introduced by design and is, by a big margin, the most likely thing to fail.

So to summarise this part.
You don’t have to do anything wrong to find yourself in a compromised situation after a link break even if you are an expert pilot. For the rest of us the situation could be far worse.

Of the two schools of thought ...
A non event that presents no problem verses a potentially serious issue the former is by far the most palatable.
But for now, even if just to humour me, accept my pessimistic view because provided there is no trade-off, to assume there is a danger is likely to be a safer option than to assume there is none.

“Provided there is no trade-off”.

To make it clear I’ll say from the onset that flying with no dedicated weak-link is plain stupid. Also if one changes the term ‘strong link’ to ‘one not too weak’ (as used above) then there is a complete change of emphasis.

So to keep things very simple lets say I am towing with 100kg of thrust with a weak-link value of 101kg. It’s easy to see that I can expect frequent breaks indeed launching might not be possible, winch tension control is not that good.
Up the weak-link value a bit. Launches are now possible but there are still frequent link breaks.
A bit more and breaks become just a few. At this point, only for historic reasons as far as I can see, it is now deemed acceptable and anything above is referred to as a ‘strong link’.

I see no logical reason for stopping at that point why not up the tension a bit more until undesirable link breaks disappear, just like sailplane towing? Naturally this does not mean exceeding or even coming close to forces needed to break the next thing in the chain.

The payout winch and other tension controlled variants were the first and one of the most significant safety devices ever to be introduced to the hang glider towing world. With a (trained) winch-man added I believe this launch method to be as safe, and in some instances, safer then all the other methods available.
Having a weak-link calibrated too close to the expected tow tensions only serves to override the far superior ironing out effect of a tension control system with a vastly inferior random and one way removal of all power. This is illogical.

So what is lost by upping the link value as above? The winch will still work limiting the tension, assuming the winch-man is something much more than some passer by he will be observing and protecting the pilot, the line can be chopped in extreme situations and not forgetting the pilot still has a release. This is all before the weak-link comes into play and even then it will still break in a jam up before anything else does!

As for the argument that a weak-link is there to compensate for an unreliable release* I say get yourselves a release with the same failure rate as your hang strap and this requirement will vanish.

There we have it Bill, two ageing (greying, balding in my case) ‘70s flyers on different teams but both shooting at the same goal!



* Purpose built machanacal releases have an almost unblemished safety record on par with hang straps and side wires but some samples are not immune to poor design and construction as demonstrated by an incident observed only last month.

[Bob Kuczewski]

My entire hang gliding towing experience consists of one tandem aero-tow at Wallaby Ranch ... where I was the passenger (thanks for the flight Malcolm). So my comments come more from an attempt to understand towing than any pretence of authority on the subject.

One of my thoughts while mulling this all over is that the severity of the glider's response to a line break must be related to the amount of tension in the line when it broke. In other words, if the tension is very close to zero before the break, then the glider's response will be very close to zero after the break. Is that generally true?

Similarly, if the tension is very high at the time of the break, then that means that the force diagram before the break shows a large force along the tow line and an equally large force opposing it. At the moment of the line break, the tow line force becomes zero, and the opposing force is converted to acceleration (actually deceleration in this case) according to Sir Newton's F=ma. So the greater the line tension at the time of the break, the greater that thrust change and subsequent deceleration will be. Is that generally true as well?

Thanks for the great discussion. It's great to see all aspects of a topic like this being explored!!

[Bill Cummings]

Thanks Mike for stating your position regarding weak-links and tow force.
I hope that the take-away the readers get is from both of our positions on this subject is to bring to mind something about towing that they haven’t thought of yet.
Hopefully the readers will find several ah-ha moments from each of our positions on weak-links and other thoughts.

It looks to me that we are not that far apart in our towing procedures with regards to tow force and weak-link strength, etc.

Perhaps a reader might think that they could use the difference between our selected runway lengths and use the difference between our weak-link strengths and tow forces.

This compromise rather than jumping with both feet into one position or the other could ease them into making decisions that best fits their skill set.

Thanks Bob for putting into words what most accurately describes why I think the way I do on this subject.

Quote: Bob K.---
“One of my thoughts while mulling this all over is that the severity of the glider's response to a line break must be related to the amount of tension in the line when it broke. In other words, if the tension is very close to zero before the break, then the glider's response will be very close to zero after the break. Is that generally true?”

I believe that is true.

Quote: Bob K.---
“So the greater the line tension at the time of the break, the greater that thrust change and subsequent deceleration will be. Is that generally true as well?”

I believe that is true also and the two quotes are the basis for my way of thinking.

[Bill Cummings]

Safety concerns with platform payout towing procedures.
In all candor I readily admit to doing two things wrong when platform towing.
On purpose I used to do more things wrong but I’m getting better at staying closer to the center of the safety envelope and not pushing the edge.

I allowed my weak-link strength to creep up to 350 lbs while platform towing. What strength should have been enough?
Answer = 220 lbs breaking strength for the weal-link with a tow force of 100 to 125 lbs.

Here is why I allowed creep in my weak-link strength.

For awhile different platform tow rigs that I had been using had more line on their drums than we could use with the 5,000’ - 7,000’ runways that we were towing on. After launching the towline would dig deep into the many wraps on the drum and sometimes completely “nest” (stop paying out) and break the weak-link.

When a winch completely locks up you are now instantly static towing too fast
.
Worse than this would be using the procedure to quickly dash out in front of the pilot by speeding up the truck. ( “Go to cruise and accelerate!”)

This is an attempt to get more line out to tow the pilot more ahead than down.
If the winch/reel were to nest, meaning lock up, you would have a low angle to the platform rig, way too much speed, and not have a climb restricting “V” bridle assisting you in keeping the nose down. You are at the mercy of the payout tow vehicle.

A lock up with excess speed from dashing out in front of the pilot will almost certainly break the weak-link, nose high, beyond the pilots ability to weight shift the nose of the hang glider down to prevent a stall.
If you choose to fix this problem by increasing the strength of the weak-link the dashing PL rig procedure still will have the potential to break the stronger weak-link when (Not if.) the winch/reel locks up. This would pitch the nose even higher. This could result into a serious break stall or worse yet a tuck and tumble.

Never trust that a payout will always work properly due to it’s precision engineering and spotless history.

The towing procedures that you adopt should have within them solutions that will address as many adverse scenarios that tow pilots can imagine. Care needs to be taken that a solution to one problem will not aggravate a different problem.

Keep in mind that if you maintain a proper angle to the platform rig of not less than 40-45 degrees your towing operation no longer requires a climb restricting attachment to the keel. PL towing doesn’t have this climb restricting rope to the keel so your correct angle the entire time off the rig is the safest answer.

If you descend or find yourself at a poor angle - release. In this situation you certainly wouldn’t want the payout winch/reel to lock up. The longer you put off the release decision if your angle of tow decreases from optimal the greater will be the risk to yourself if the payout should freeze up.

Static towing once 40-45 degrees has been attained no longer needs a climb restricting keel rope and is sometimes in the pilots way. This keel rope getting in the way has resulted in pilots rigging up without one. Thus further pushing the edge of the safety envelope. One tow method was named Pro Tow.

Removing the keel rope while static towing and increasing the weak-link strength has what I call a synergetic (greater than the parts) deleterious effect on the towing safety envelope. A safety issue deteriorating in logarithmic proportion not simply arithmetically.
It might look as though I’m wandering off topic bringing up the static towing during a pay out platform launch topic. Poor towing procedure allows pilots themselves to do this vacillating between the two methods if they are not maintaining the proper tow line angle.

If your angle to the PL rig is low (poor) it is comparable to early stages of static towing.
Low angles are best handled with a climb restricting “V” bridle for static towing.
Proper angles while platform towing have you not as close to the edge of the safety envelope but right in the middle.

Remember your keels angle to the horizon should not exceed 60 degrees.

The tilted earth theory while towing is no longer in play with the loss of tow tension.
Loss of tow tension can have you at or beyond 60 degrees to the horizon. How much so depends on your choice of towing safety procedures.

These procedures must take into account, airspeeds, bridles, weak-links, angle of tow (angle of the towline with the surface), angle of the keel with the horizon, which are the major concerns together with other minor concerns.

Trusting a mindless automatically tension adjusting payout winch or even a driver adjusting speed while watching a pressure gauge in a truck is a safety procedural paradigm that will never be all inclusive. There are times when procedure and automation actually add to a hazard.

(The following example will not find its way into a training manual but is here to stress a point.)
Example: A tow pilot died because he was used to flying “pilot in command” on constant radio transmit, without a pressure gauge. He was truck, pulley, towing for his first time with a pressure gauge.
I watched the video of his death that his girlfriend took.
After launching a thermal gusted him 90 degrees of tow to his right. He pulled in and turned left which snagged the two tow bridle ropes to his body over the left wheel axle (minus the wheels this day). The axles extended out of both ends of his base tube. Pulling in to reduce tension he undoubtedly thought, like I have on similar occasions, that he could remove the snag then radio for more speed. However the drivers procedure was to maintain pressure while towing, (Much like a mindless pressure adjusting winch will do because of it’s design that didn’t encompass all variables that a pilot is exposed to.) The tow vehicle sped up. The glider instantly locked out to the left. Two seconds later he died on impact.

There are times when I pull the bar in to reduce tension. I don’t want something or someone on the ground overruling me and restoring that tension until I command it. (This is for experienced pilots only not students).

I tell drivers with pressure gauges, “Whether the gauge is in the red or at zero do what I say. I am the pilot in command.”

Any winch tension that I use from now on will be adjustable, “On the fly.”
I tell the driver what to do with speed and tension adjustments over the radio.
(For experienced pilots only. Not students.)