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Prepping for an FJC later this year and I have been reading everything I can. An article on here stated that on a slider up jump, a lower deployment is safer. My question is why? Is it object dependant, i.e. the slider could negatively affect heading on a B or E jump?
On the surface it would appear the opposite, that even a mesh slider would cause the canopy inflation to be a bit slower (not necessarily good for a low deployment) so the only other thing I could think of was heading. Educate me on this please.
Edit to add I realize an off heading deployment is an issue regardless but a lower deployment could give a little more seperation from the object.

heading performance is correct. the slow opening may cause the canopy to "seek around" and cause a higher probability of off heading openings. i seem to remember that happening to me on a dam. suck it gremlins !!

Slider-UP deployments are a little
trickier than Slider-Off/Down jumps.

NO Slider = 4 seconds MAX while with
a mesh slider you can take anywhere
from 3 seconds to 63 seconds, which
is why there is greater range in size
and type of pilot chutes used because
airspeed from different delays has a
profound affect on deployments.

Short delays, slider-up, usually have
very bad heading performance, I know
from personal experience. Once took
4 seconds when I packed for 6 seconds
combined with a slight cross wind gave
me a 180 and linetwists but good video.

I do not know what you were reading
but my guess is that it cautioned newbie
jumpers about the very common panic
pull, where you exit, freak, shit a little,
and then throw a pilot chute 12 feet

Because if you fuck it up, get it all wrong and end up running into the object its better to only bounce down the last 50ft instead of 500ft



Very. But not because the object affects the heading but because the object affects what people believe to be acceptable heading performance for a particular jump ie. all the shit people pull at the Perrine.



Simply adding a slider on the same object won't necessarily give you more separation for several reasons. Here are two right off the top of my head:
1. Jump from 500ft without the slider and do your intended delay you and you will get x amount of separation. Jump the same object with a slider and the slower opening will most likely force you to pull at the same altitude if not higher than the the slider off jump to accommodate for the slower opening. So even though your canopy will open lower the separation remains pretty much the same.
2. Another common occurrence on walls is that a solid 3 second slider off will open you inside a massive safe over hang while the 5 second slider up jump will have you opening right up against the talus.

I think the theory is the lower you go means more track time which means more object separation which means more time to deal with the off heading.

^This
+1

If you take this logic and extend it to the extreme, you will come up with something like what Dwain Weston wrote in an article once.

Paraphrased: Your 'safest' opening height is such that you would land on the ground before hitting any object regardless of opening heading and direction of canopy flight.

This of course is based on the theory that object strikes are your biggest danger.

There is definitely logical merit to this theory, but it also means your window for pull time is dependent on object height and your trajectory from said object.

On slider-off objects that window could easily be much smaller than the normal variability in the deployment process and so using that strategy on too low of an object will eventually result in you hitting the ground without a flying parachute overhead (much like Dwain wrote somewhere about freefalling really low objects). That is of course assuming you have superhuman abilities to track time and altitude and pull with nano-second precision.

On slider-up objects, given the right combination of height, shape, trajectory and winds, sometimes you can quite safely apply this theory.

It's all about knowing what size the window is that starts at:
-pulling low enough that you'd land before hitting the object if you had a 180 and tons of linetwists
and ends at:
-pulling so low that you will have a flying canopy overhead and a single digit second canopy ride

Compare the size of that window with the normal variability in height used during deployment for your system at the relevant airspeed and you should have some idea of whether you choose to apply that approach.


Now,

please do not ask me for numbers on any of these times/heights/variabilities, because no-one has accurate data of a statistically valid sample size.

i.e. Welcome to BASEjumping

Thanks for the 411 ;-)

nervous jumpers tend to pull higher than planned. (watch BD video if in doubt!)

pulling too early on a SU jump can lead to less reliable heading performance. this happens because of the low speed snivel. after a jumper achieves terminal velocity, this becomes a non-issue.

resisting the urge to pull at 4, rather than 7 seconds can prevent carnage.

Thanks guys. Good to know my thought process was in the right vicinity.