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while hiking in the california wilderness this last weekend, i came across a granite cliff with around a 350' rock drop. the thing is, bottom of this cliff is around 9000' ASL. kinda got me wondering what effect this kind of altitude has on openings (delay, etc.). i searched around on this forum, but for the most part all i found was discussion of the effects it would have on landings.

also, just to clarify, i'm not planning to go jump it like some of the kids that post on here. i'm a newish skydiver and just wanted to see how that sort of thing works. :)

I jump regularly with landings between 6000-8000 and have not noticed a difference in the opening but this is not super low objects where it is a concern. Landings are a little faster.

I started skydiving in a Mountain town in Colorado where the landings were 8800' MSL so most parachute openings were 2-3000' above that, but since that's where I made my first jumps, it all seemed normal at the time. I have a number of BASE openings above 12000' and even 13000', I never felt that there was anything especially unusual in opening characteristics. Anyway, that's just my perception, others might have a different perspective,

Regards,B.

Let me know where you e found this cliff and I will demonstrate the effects first hand

When we did the "Skydive Everest" jumps we were opening at around 15,000FT MSL. I expected it to make a difference and was pretty anxious but it ended up being a non event. This was on a Navigator 260.

On the other hand that was at 4000 AGL, I might be more scientific about it at 350. I have to think PC performance is linked to altitude\density altitude.

When worried I size up on PC to take the edge off (or just let my buddies go first).

Are you looking for quantifiable, scientific predictions? or applicable advice on the differences?

awesome, thanks everyone.

calvin, if you know enough theory behind air density and it's effects i'm all ears for sure. :)

i was kinda just asking to see if anyone had any practical knowledge or experience, but the if you or anyone knows enough of the science to practically apply it, that's sweet too.

I can definitely say that wingsuit starts are noticeably longer at these altitudes. As for openings? it goes kind of like this:
We basically have 2 stages of interest
1. PC inflation and its pull force.
2. Canopy inflation.

For a slider down jump, PC inflation is critical. Lower air density definitely affects PC performance.
As for canopy inflation, that stage occurs right after packjob hits clean air(this is why we have that rubber band on the lines. linedump hurts). And altitude loss between that and inflated canopy for slider down is what? 10 meters? So if you have a density effect of, say 70 percent(which is a lot in terms of air pressure), you would have 17 meters instead of 10. Now 350 feet ain't much, so every inch counts, put that is nothing compared to PC performance.

So to sum it up, I'd recommend a 48" ZP no apex, hand held upyours go'n'throw. And have that center cell fully exposed.