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SkyHopperZH

Severe Linetwists (not diving yet). Cut or not?

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Questions to the experienced jumpers:
If you fuck up the deployment in your large wingsuit and end up in severe line twists (8 full rotations) and keep turning in the wrong direction:
Would you fight as long as altitude permits or cut it away early?

It happened to me recently. I was afraid that by twisting up more the canopy might end up diving and making a cutaway harder or impossible (i heard rumors of people being not able to cut away in severe line twists cause the cables were blocked by the twist). So i lost my cool and did an early cut.

What's your opinion on this?

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I was under a very stable canopy, that was twisted, and in a very slow turn. I didn't have experience enough to know to use the arm wings as leverage to get out of the twist. I unzipped my legs and tried to kick out. That didn't work because the drag of the tailwing then acted like a rudder.

At 2000 I cut away (hating to because of a line twist) as trained. I had given it my best shot and was getting tired. That made it clear that it was not going to get better if I just kept trying.
Instructor quote, “What's weird is that you're older than my dad!”

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SkyHopperZH

i heard rumors of people being not able to cut away in severe line twists cause the cables were blocked by the twist



This is not a rumor, this has killed people, that is why modern risers have hard inserts. If your risers do not then get them changed because it does not take many line twists to lock your cables in there.

Riser hard housing inserts aside if you go into a spiral you will start pulling more G forces and this can increase the pull force required to chop because of the additional load on the 3-ring transferred ultimately to the loop around the cable. You have mechanical advantage but loads can get high in a spiral causing a hard chop even if your cables are clear.

Nowhere do you mention altitude, and that's an important factor.

I have no desire to second guess your decision to chop. You lived to jump again. Others who hesitated have not.

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SkyHopperZH

Questions to the experienced jumpers:
If you fuck up the deployment in your large wingsuit and end up in severe line twists (8 full rotations) and keep turning in the wrong direction:
Would you fight as long as altitude permits or cut it away early?

It happened to me recently. I was afraid that by twisting up more the canopy might end up diving and making a cutaway harder or impossible (i heard rumors of people being not able to cut away in severe line twists cause the cables were blocked by the twist). So i lost my cool and did an early cut.

What's your opinion on this?



Altitude is your friend and gives you a bit of time to work a problem, but you have to factor in a lot of variables, quickly.

I don't think you can have just a single decision altitude but you can have a minimum that gets increased based on other variables. Mine is 2000 but I have found myself increasing it due to additional hazards, which have included:

- Being over the middle of a deep forrest and needing to get under a controllable canopy so that I could clear it, even though the line twists were stable. Same happened to me over a swamp!
- Being in a huge wingsuit and knowing that the risk of getting into another set of reserve line twists is an issue.


Bottom line is that chopping too high is far more of a forgivable offense than too low! ;)
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Only you can say for sure - depending on what the situation is - whether it's worth trying to fight longer.
How fast is the spin? How does it compare to previous sets of line twists on this same canopy? How high are you? How tired are you? Are you confident that the situation is improving?

There's certainly a good case for cutting away early. Biggest reason I can see for that would be to have as much time as possible to fix line twists on the reserve.

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Thanks everybody for the opinions. Appreciate it.
I was @ 2900ft when i chopped. Considering it was the last jump of the day
its fair to say i didnt have plenty of energy left ;)
Hard housings, check... Good to know it's a valuable feature.

@dthames: Could you elaborate on using arm wings as leverage to get out of a twist? Never heard about that so i'm curious to learn how that works for you.

Happy jumping :-D

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@dthames: Could you elaborate on using arm wings as leverage to get out of a twist? Never heard about that so i'm curious to learn how that works for you.

Happy jumping :-D



If the canopy is inflated and stable but you have line twists.....with a wingsuit, this is what you can easily do. Look up and make sure you know where the nose is, relative to the direction that you are facing. In this example, you are flying backwards and you need to untwist by turning clockwise. You throw out your right arm. The air that you are flying through hits it at your forward canopy speed. Very quickly your right arm is now trailing you, as you have turned some 90 degrees. Pull in your right arm and thrust out your left arm, but be sure to extend it out and back a little so the wind will hit the front part of your wing to continue to drive you in the direction that you want to turn. It requires a bit of timing but it is not difficult. After two revolutions, you have enough rotation speed to stop with the arm thing and just let it unwind.
Instructor quote, “What's weird is that you're older than my dad!”

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First off: if your main canopy is overhead and going slow, you have more time to deal with line twists. Glance at your altimeter to confirm how high you are above decision altitude.
Secondly: leg position can make or break line twists. More precisely keeping you legs and lower torso arched ALL THE WAY through deployment can prevent line twists, especially when jumping a wing-suit. It took me a dozen jumps to figure out that most of my wing-suit, line-twists were caused by lazy legs allowing the relative wind to hit the BACK of my leg wing.
Finally, hard-housing inserts on risers only solve half the problem (with difficult cutaways) because the second part of the problem is rings twisting relative to each other. Once the riser rings start twisting - relative to the harness ring - pull forces vastly increase. This problems favours cutting away the earliest you recognize that you are suffering DIVING line-twists.

The key difference is whether the canopy is overhead or diving. When the canopy is diving, you are less than a minute from impact and need to cutaway NOW.
OTOH if the canopy is overhead, stable, turning SLOWLY and only suffering from twisted lines, you have up to a minute to cure line twists before reaching decision altitude.

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I had a similar problem and chop because of jumping a canopy severely out of trim (inspection revealed outer lines about 6" too short and inners 3-4" too short (~600 jumps on original lines). The result was it very much liked to stay in line twists once in them. I tried kicking out and fought it for about a minute, video verified, (from ~3.8k to 3k). My back started hurting from kicking so much and I was headed down wind so I decided to chop a little above my decision altitude of 3k because my effectiveness in fighting it was diminishing and the situation for landing was getting worse. You are NOT OBLIGATED to fight something to decision altitude if you know it is a losing battle, as previously mentioned, it is a bare MINIMUM.

For what it is worth,

On all WS jumps I pull at 4k (I have over 300 now, so it's not just beginner conservatism), I'm usually fully inflated and flying by 3.8-3.5k. My "soft" decision altitude is 3k, basically unless I have a really good reason to keep it going beyond that I won't (for all practical purposes this is my decision altitude), my absolute hard decision altitude is 2k, no matter what, handles are going to get pulled at 2k. I have audible warnings for both 3K and 2K.

As mentioned before, chopping too high is better than too low. There is a delicate balance between riding something too long and being "chop happy" and cutting something you shouldn't. But ultimately you have to trust your reserve and a chop when you didn't have to is better than not chopping when you should have. I remember thinking about this on my low speed line twist chop, "ok, you might be able to get out of this, but your landing options will be poor and you won't have much altitude and you'll be very tired from fighting it so much, and if you can't get out you will have a very bad landing in a semi-urban area and the chance of getting seriously hurt is high, if you chop, there is a 99.99% chance your reserve will function properly and you will be completely fine and land in the main landing area." I went with the chop, landed at the DZ and was able to recover my gear. It is a game of probability.

Your decision was an appropriate one, if you saw the problem getting worse and not better then the only decision is to chop, is doesn't matter what your altitude is or if you "might" have been able to get out, because you also "might not" have.

The only chops I've ever seen that I would criticize were low experience jumper (sub 100 jumps) that chopped a long snivel at like 4k. For their experience level though it could be appropriate because they were experiencing a problem they couldn't fix and had no experience with (i.e. they didn't know it was probably just a long snivel). For an experienced jumper it might be a sign of panic.

If you processed the information and decided a chop was the best course of action, then you almost certainly made the right decision. If you panicked and chopped because you didn't know what else to do, that could be a problem and suggest you need more experience and should be pulling higher etc (but from your description it doesn't sound like that is what happened).

P.S. +1 for the SkyHook. Makes a spinning WS malfunction a much better chop because it is so fast that you don't really have time to go head down or spin the reserve up too much. (I've heard of several cases first hand where people have been spinning hard (swoopers to 170 size canopies) and a SkyHook deployed them parallel to the ground with 1 or 0 line twists. I think there is a good real life chop vid on UPT's website where a wingsuiter was spinning hard and chopped, the SkyHook had the reserve out so fast there were no line twists. My low speed chop was also a SkyHook and I started to fall backwards but the reserve was already out and the snivel kept me from rotating more than 30 degrees back. A recent photo I saw of a very experienced jumper on an Aura2 with a normal RSL had him head down for the snivel with reserve lines on either side of his head, scary s**t. He was looking at his feet and the sniveling reserve at the same time :S

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SkyHopperZH

Questions to the experienced jumpers:
If you fuck up the deployment in your large wingsuit and end up in severe line twists (8 full rotations) and keep turning in the wrong direction:
Would you fight as long as altitude permits or cut it away early?

It happened to me recently. I was afraid that by twisting up more the canopy might end up diving and making a cutaway harder or impossible (i heard rumors of people being not able to cut away in severe line twists cause the cables were blocked by the twist). So i lost my cool and did an early cut.

What's your opinion on this?



Just yesterday one of my friends had a cutaway. Highly experienced jumper, but bad deployment position, large suit, and many twists. His canopy was stable. The twists had somewhat restricted his head movement already. He tried to get untwisted and it twisted up a bit more and started a rotation. 2000 feet now so, he cut away before it had a chance to get worse.

You don't hear much about all those that do the right thing.
Instructor quote, “What's weird is that you're older than my dad!”

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