You're below 1500ft, and...

[mdrejhon 8]

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if they find themselves with an unlandable canopy below 1500' they will ride that fucker in?

I think it's complicated by whether not "linetwists" means "unlandable"

Under a Velocity, if it's spinning, they definitely are. Spinning at 80mph vertical fallrate in uncontrollable linetwists -- that's going to be fatal if you try to land that.

Under a low-aspect-ratio square canopy loaded at, say, 0.8 through 1.0, flying straight ahead, linetwists are landable with PLF with no injury. They are often easy to kick out in less than 100 to 200 feet altitude. BASE jumpers (while I am not one, I do know a few), often 0.7WL, have to be prepared to land in linetwists, if necessary. This option is certainly safer than a low cutaway.

Just another monkey wrench to throw in this already controversial decision.

[jakee 1,489]

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You spin up into line twists for whatever reason etcetc

simple answer: don't do this, for what ever reason

Simple, but useless.

Do you want to have an ideagasm?

[erdnarob 1]

A lot of good advices here but I think there is no general rules to solve a line twist problem. It is indeed a case by case solving.
1) if the canopy is fully inflated and flying straight you can take some time to undo the line twists by kicking the legs and/or using you hands on the risers to start untwisting them. I would not recommend at all to unstow the brakes.
The unstwisting starts always slowly and go faster and faster.
2) if the canopy starts spinning in the same direction than the line twists, you are in trouble and you should decide quite early to do your cut away.
Note: in case of severe line twists it has been seen that a cut away is impossible to perform since the cut away cables are so tightly squeezed at the riser level. That's why I recommend everybody to have risers equiped with anti twist channels in plastic or preferably in metal (to be installed by a rigger) to avoid yellow cables to be caught by the twisted risers.
How to avoid line twists:
a) stow your parachute as symetrical as possible in the POD.
b) leave between 18" to 2 feet length of suspension line unstowed. Too short of a length can make line twists since one side of the POD can leave the container before the other side and starts a spin.
c) after throwing away your pilot chute (or pulling it out), make sure you are still flying straight by looking at the horizon. Looking at your pilot chute and parachute deployment might generate a line twist.

Learn from others mistakes, you will never live long enough to make them all.

[DanG 1]

erdarob, you give good advice. What I think you are missing is that in the OP it is presumed that we are already flying around and line twists develop. This means that the brakes are already unstowed and, in the most common cause for low line twists, one is probably pulled down much more than the other.

In this case, it is unlikely that your parachute will be flying flat and level. Letting up on both toggles may allow your canopy to return to straight flight, but it may not.

All jumpers should have two hards decks. One is the altitude where they need to get a functioning parachute over their head, and will release a malfunctioing main. Many people choose something around 2,000 feet for this first hard deck. The second hard deck is where you will not cutaway what you have, even if it isn't working, and instead try to get as much fabric out as possible. Many people choose 1000 feet as this no-cutaway-below altitude.

At 1500 feet with self-induced or collision induced line twist I would cutaway and pull silver as fast as possible (assuming no entanglement or wrap). I also choose to jump with an RSL on one rig, and a Skyhook on the other. I hope that using those devices will increase my probability of getting a reserve out fast in such a situation.

- Dan G

[T-box1990 0]

Im a new student (only 2 jumps AFF) so I could be wrong. I have been told that with line twists spread the risers and kick out, if this fails to work at 1000ft or above cut away and deploy your reserve. Basically I have been taught never to ride an unlandable canopy below 1000ft. When in doubt whip it out!
(This is after I clear student status, our student decision altitude is 2500)

"If piloting an airplane is flying, then driving a boat is swimming. If you want to experience the element, you have to get out of the vehicle"

[erdnarob 1]

OK I am with you. There has been another thread on this forum about a jumper (with video) who intentionally pulls suddenly the left toggle and get line twists. I answered that one by saying that was a problem of conservation of angular momentum. The body doesn't follow the canopy right away and line twists are the result.

If that happens because of a misconception of what should be a good canopy piloting, well, below 1500 feet it depends on the behavior of the canopy. If the canopy is not landable (like spinning in the same direction than the line twists) a cut away would be necessary but remember that if doing so, the AAD is possibly going to fire. That bad canopy piloting will result in a costly bill (reserve repack, a new AAD cutter and possibly the lost of the main parachute and reserve free bag and pilot chute). An expensive lesson.

Learn from others mistakes, you will never live long enough to make them all.

[aresye 0]

I agree with what you said, except for the AAD fire. Below 1500ft, if you cut away, I doubt you would accelerate enough for the AAD to fire anyway.

Skydiving: You either learn from other's mistakes, or they'll learn from yours.

[humanflite 0]

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I agree with what you said, except for the AAD fire. Below 1500ft, if you cut away, I doubt you would accelerate enough for the AAD to fire anyway.

True. The AAD would be of very little use below 1500ft, (any version), maybe the student version which opens at 29mphiirc would fire, but who knows.


As stated by some others, cutting away below 1000 feet unless you are using a skyhook is a very risky move even if your using an RSL, and your reserve may not inflate in time...
I suppose it would depend on the reserve used and if fate was on your side.

Im with the 'get as much fabric above my head as possible' school of thought although it would depend on the canopy I was flying.
If I was on something like a Velocity (Im no where near experienced enough to do so yet but theoretically speaking) it would be a no brainer, a slightly bigger non elliptical canopy say 150sqft and upwards and I would possibly elect to not flare and PLF like a mofo.

Just goes to show the value of something like the Skyhook in a lowdown n potentially dirty scenario such as the one in this thread.

[erdnarob 1]

Theoratically it takes 3.5 second of free fall to reach 35m/s or 78 mph (the Cypres firing set up for Expert and Tandem mode or the Vigil Pro and Tandem mode). With the air resistance say lets add 2 more seconds which makes 5.5 seconds of freefall.
A jumper cutting away at 1500 feet will make a vertical distance of about 400 feet within 5.5 seconds which makes an opening at 1100 feet (840 + 260). This exactely the firing altitude of the Vigil (1100 feet) when in an upright position like it is the case at opening and since there is not anymore a differential pressure (260) between chest and the back on the jumper). In the same upright position the Cypres will fire at 1010 feet (750 + 260)).
I know that a jumper cutting away at 1500 feet may choose to pull his reserve immediately while others will prefer to have some speed.
But suppose now that the jumper is cutting away at 1300 feet or lower. As I said he is likely to get his AAD fire if he prefers a slight delay for a more positive opening.
Note. I don't think so there is a big difference in vertical distance traveled for a complete opening between doing a hop and pop and waiting 3-4 seconds before pulling after a cut away.

Learn from others mistakes, you will never live long enough to make them all.

[ozzy13 0]

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As stated by some others, cutting away below 1000 feet unless you are using a skyhook is a very risky move even if your using an RSL, and your reserve may not inflate in time...
I suppose it would depend on the reserve used and if fate was on your side.

In a FJC they teach students to decide where to land by 2500 ft. They also tell students to decide if they are going to land with the parachute that is over their head or cutaway at that alt. If a student has a problem below 1000 ft they are to just pull their reserve with out cutting away.

With that said!!!

If you are at 1000 ft with a mal over your head you are not falling as fast as with nothing over your head. That means you do have more time before the ground. Reserves open faster than mains.

I would cutaway at a 1000 ft with a spinning canopy!!
Everyone is different and I would want to get rid of the bad canopy if I could!!!

Never give the gates up and always trust your rears!

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[JohnMitchell 16]

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I would cutaway at a 1000 ft with a spinning canopy!!
Everyone is different and I would want to get rid of the bad canopy if I could!!!

I've seen several cutaways( and done one) from around a 1000. All were successful. You must pull your reserve in a timely fashion. I don't agree with people who trade altitude (they may not have) for stability.

[D_22359 0]

I tend to agree with John. Chop and pull... QUICKLY
I think you still have time for a good reserve but not much. I dont have an RSL and havn't used one in a long time so I only have one EP with a bad canopy out above 1000'... chop & PULL. Everything changes depending on the canopy in question big slow square's= more time to evaluate and make a choice. HP elipticals mean less time but should also mean more experiance. You need to know your gear.

The rules I was taught were this:
1) PULL
2) PULL with stability
3) PULL @ your assigned altitude

It's you ass make a choice you can live with.

Bill

Sorry for the crappy spelling

[ozzy13 0]

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I would cutaway at a 1000 ft with a spinning canopy!!
Everyone is different and I would want to get rid of the bad canopy if I could!!!

I've seen several cutaways( and done one) from around a 1000. All were successful. You must pull your reserve in a timely fashion. I don't agree with people who trade altitude (they may not have) for stability.

I use skyhooks on my rigs and at that alt. who cares about stability!!! I just want something good over my head and fast

Never give the gates up and always trust your rears!

[livendive 8]

Obviously what Bill *meant* to say is

PULL
PULL at a safe altitude
PULL stable at a safe altitude

Being nice & stable when you pull at 100' isn't going to make your eulogy any better.

Blues,
Dave

"I AM A PROFESSIONAL EXTREME ATHLETE!"
(drink Mountain Dew)