Pulling at lower altitude than declared at boarding.

[Tolgak 0]

While it's been a while since I've gone jumping, a phenomenon that's been happening during that time has really bugged me.

In a good half of the jumps I've done, on which I was not the last man out, I've seen jumpers blaze past me after my canopy has been opened. Every load I have been on establishes pull altitudes to avoid collisions, but I have yet to go a day without seeing someone disregard the altitude he told us he would pull at.

I make an effort to have my pilot chute in the air at the exact altitude I specify, but it now looks to me that it's a dangerous idea. I realize that it takes a few hundred feet to open. But that doesn't explain why a guy will get 1000 feet below me before he moves his hand to his hacky.

Is this a common problem at your DZ?
Am I being more concerned than I should be?


Also, a bonus inquiry. I jumped at Clewiston a while back, and the cut-away cord on the rented gear would come out of its sleeves after opening. I consulted the rigger there and he said that this was a normal occurrence and nothing to worry about. He insisted that it was the proper length. Is that true, or should something like that never happen?

Dropzones are terrible places for inspiration. What does one think when one looks up for a sign only to see a bunch of people falling?

[GLIDEANGLE 1]

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I jumped at Clewiston a while back, and the cut-away cord on the rented gear would come out of its sleeves after opening.

Are you referring to the "sleeves" on the risers which hold the free ends of the cut-away cables?

The choices we make have consequences, for us & for others!

[Tolgak 0]

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I jumped at Clewiston a while back, and the cut-away cord on the rented gear would come out of its sleeves after opening.

Are you referring to the "sleeves" on the risers which hold the free ends of the cut-away cables?

Yes I am.

Dropzones are terrible places for inspiration. What does one think when one looks up for a sign only to see a bunch of people falling?

[Will_Evo 0]

Ive had people fly past me before too, not very close to me, but ive been able to see them fall past me. I think it's because of the way loads are organized, aka not by opening height, but by discipline. A few of the DZ's I have been do biggest RW group to smallest RW, than biggest FF to smallest FF, then AFF, Tandems, and CRW. It might just so happen that someone on the 3 way climbing out after your 4 or 5 way may be opening lower than you Just a guess as to why you see this happening, but I imagine as long as a good 5-6 seconds is kept between groups, you don't have to much to worry about. I could be wrong though, just a guess on my part.


-Evo

Zoo Crew

[kallend 1,623]

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Every load I have been on establishes pull altitudes to avoid collisions, ?

HORIZONTAL separation is the way to avoid collisions. You can't trust vertical separation for the exact reason you have discovered.

...

The only sure way to survive a canopy collision is not to have one.

[skybytch 259]

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HORIZONTAL separation is the way to avoid collisions.

Horizontal AND vertical separation is even better.

[NewGuy2005 51]

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Every load I have been on establishes pull altitudes to avoid collisions, ?

HORIZONTAL separation is the way to avoid collisions. You can't trust vertical separation for the exact reason you have discovered.

I agree. Even if there is a 10 ft. VERTICAL difference in your pull altitudes, if the next guy on the load hits you, you will be just as dead as if there was a 500 ft difference in you pull altitudes.

Everyone can pull at the "same" altitude and no one will be in the saddle at the same altitude.

The only safety is in HORIZONTAL separation.

[AndyMan 7]

It's extremely difficult to accurately estimate altitude under a parachute or in freefall.

While it's smart, prudent, and wise to organize ourselves in the airplane by exit altitude, this is not enough to guarantee a sufficient separation of jumpers during deployment.

First, remember that altimeters are very crude devices. Even those that have precice digital display have very crude barometers as their primary altitude detection device. These tools should not be considered precicely accurate .

Second, remember that the person reading the altimeter is a human, and humans aren't terribly precise either. For some people (especially newbies) there's going to be a delay of often up to half a second between registering the indicated altitude and acting on it.

Third, remember that even when a person decides to start the process of pulling, it can take time to wave off, find the handle, and pull.

All these add up to the fact that declared pull altitudes are a very rough estimate. If someone declares a pull at 3000 feet, I would not be surprised at all to see them pulling anywhere between 3600 and 2400 feet - a range greater than 1000 feet!

When you're sitting there under canopy and see someone blow by in freefall, it can appear as though their smoking past their declared pull altitude, when in-fact the difference is likely easily explained through the three factors identified above.

It's for that reason that the skydiving community has largely moved to enforce horizontal separation as a superior means of ensuring pull safety.

Of course, horizontal separation has its whole bag of issues too, so your best bet is to try for both.

As for the cable coming from the sleeve in the riser, no - it is not "normal". It is an indication the cables are a bit too short for the rig. However, as long as there's a good 4 inches of excess cable above the cotton loop in the riser, it's a minor annoyance more than a critical issue.

_Am

__

You put the fun in "funnel" - craichead.

[NewGuy2005 51]

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While it's smart, prudent, and wise to organize ourselves in the airplane by exit altitude, this is not enough to guarantee a sufficient separation of jumpers during deployment.

I agree with everything you said, but I'm wondering how you would organize the load by altitude?

[AndyMan 7]

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I agree with everything you said, but I'm wondering how you would organize the load by altitude?

A few examples:

Most dz's put "high pullers", including Tandems, Students, and CRW out last.

On a full load of hop-n-pops, jumpers usually self-organize by planned deployment altitude, since there will no tracking to achieve horizontal separation. That said, it's becoming more common to see jumpers organize by wingloading, but that's a different issue.

_Am

__

You put the fun in "funnel" - craichead.

[kallend 1,623]

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HORIZONTAL separation is the way to avoid collisions.

Horizontal AND vertical separation is even better.

You can't trust vertical separation for the exact reason the OP discovered.

...

The only sure way to survive a canopy collision is not to have one.

[billvon 2,400]

>Most dz's put "high pullers", including Tandems, Students, and CRW out last.

While that's true, I think that has more to do with tandems/CRW being able to make it back from longer spots than because of desired vertical separation. It's a nice side effect though.

As others have said, all you can really count on is horizontal separation. If you can get adequate horizontal separation, and _then_ add in some vertical separation, even better.

[Butters 0]

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HORIZONTAL separation is the way to avoid collisions.

Horizontal AND vertical separation is even better.

You can't trust vertical separation for the exact reason the OP discovered.

You can't trust vertical separation because of malfunctions.

"That looks dangerous." Leopold Stotch

[rehmwa 2]

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HORIZONTAL separation is the way to avoid collisions.

Horizontal AND vertical separation is even better.

You can't trust vertical separation for the exact reason the OP discovered.

Horizontal is the best item - (I'll except for CrW and Tandems for disparate reasons)

relying on fun jumpers for vertical separation is just wrong



that sets up exit order pretty clearly when considering drift factors

(WITHIN a discipline - I'm a big fan of trying to ensure the highly loaded canopies are positioned to land first - IMO this is smarter than ordering WITHIN a fall rate discipline by group size)




we had a small plane this weekend - typical load was 4way, one or two FF, and tandems/Students

just a little wind up and nothing down - spot well short of the airport for first out

So - since the plane was moving pretty good (ground speed, remember air speed is always about the same no matter what the winds) - there was little time between the groups

the winds up being higher speed from the lowers, but in the same direction and upwind jumprun - indicated RW before FF (but the difference was so little, I don't think that mattered much in this "specific" case)

the 4 way had big canopies
one FF had little canopies
one FF had big canopies

so, 4 way out first
no delay but relaxed climbout gave sufficient separation
FF (little canopies) out 2nd
no delay, but relaxed climbout gave sufficient separation
FF (big canopies) out 3rd
all the working stuff out last

it worked very nicely

the 2nd out was directly over the airport and lowest on opening (even though out 2nd, not 1st) - get down and out of the way

the 4-way landed 2nd

the other FF 3rd

zero traffic, plenty of separation, the entire day with this method went super clean

the ONLY traffic issues was AFF instructors under their rockets spiraling down into the fun jumpers stackup - but that's not due to vertical or horizontal separation - that's something else entirely....

...
Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[danielcroft 2]

I'm loading @ 1.23. I jump with people who load up over 2 regularly. I don't know if loading based exit order is really practical in all but the most convenient situations. Maybe I'm missing something?