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skr

Dealing with uppers

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Well, I've been in kind of an out phase with respect to
skydiving and dropzone.com the last few months, but a
local jumper, Courtney Frasch, and then listening to
people talk on Safety Day, sort of prodded me to take
another stab at dealing with upper winds.

I did it in two parts.

http://indra.net/~bdaniels/hidden/sg_skr_dealing_1_uppers.txt

is mostly words and thoughts and conclusions.

For the hard core who want to see ascii diagrams and
mathematical handwaving I put that stuff in part 2 at

http://indra.net/~bdaniels/hidden/sg_skr_dealing_2_tables.txt

It all makes sense to me, but of course my writing always
does make sense to me until other people start reading it.

Maybe someday I will send some version of this to USPA
and see if any of it makes it into the SIM.

I know it's not as pressing as canopy control but I really
think after all these years of discussion there should be
something more than just "leave more time".

Skr

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wow! that stuff is really interesting. just made a copy to my hd cause it will take some time to get into the depth of it all.
and its definitely something that every LO should read and consider for himself!
thanks for a great post!


(sometimes it really bugs me that english is my second language)
The universal aptitude for ineptitude makes any human accomplishment an incredible miracle

dudeist skydiver # 666

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Nicely done, Skratch!

Some random thoughts:

1) Knowlegdable skydivers ask for, and pilots report, about upper winds. Your discussion seems to indicate that we should be concerned with ground speed on jumprun.

Various planes have different airspeeds on jump run, pilots fly at different speeds on jump run, and jump run may not be going directly into the uppers. So the relevant question to determine how much exit separation is required is "how quickly is the plane covering distance on jump run?"

2) In really strong uppers, it would be great if the spot was such that the first group opened over the landing area, or long of it. Then there would be no need to fly up jump run.

Of course this might work if winds at canopy flight altitudes were also strong and in the same direction as the uppers so that the last group could make it back. If they are opposite the uppers, or weak, the last group will not make it back, or have to do a go around.

(Kudos to Mile-Hi Skydiving: On safety day, they explained that they were quite willing to do go arounds to promote safe separation between groups. At DZ's where it is not safe or convenient to land out, this is a great philosophy. At DZ's like Skydive Arizona, you can often get back to the hangar quicker by landing out. You might get picked up by the van and the ever vigilant Bryan Burke, and ride back, rather than walk.)

Perhaps the answer is to arrange jump run perpendicular to the uppers on high wind days. Then there would be no reason to fly your canopy up jump run. The jump run would have to be shortened to ensure that everyone gets back to the landing area. But it's better to have adequate separation and do a go around than to die (or perhaps just be wishing you had a change of underwear after a close call).

3) Your discussion about using the ground as a reference is right on! I have had the same thoughts for a long time, but have never heard it put so succinctly. To ignore the ground is to lose the most solid dependable reference we have. In the strictest, most pointy-headed intellectual way of thinking, the ground probably isn't important for determining exit separation. But I don't know of any skydivers who are that pointy-headed on jump-run. Every now and then (perhaps not often enough) people tend to think of the anticipated freefall manuevers while on jump run.

4) The idea of having a GPS at the door is great except for one drawback: If it happens to quit working, people will be lost! I think it would be a great training tool. People could reference the visuals to actual data. The missing element then would be climb out times. There are rare occasions where a group anticipates a 15 second climb out and manages to get it done in under 10 seconds. If ground speeds are 60 mph this puts the group almost 500 feet closer to the prior group!

Keep up the good work! Perhaps some day you can publish the

"S(kratch)IM!"

Brian

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I found myself hesitating about reading this, because I knew I would have to think about it -- but I did, and I was very happy to see Brian's comments, and others, since this issue of dealing with upper winds is huge in Colorado.

Anyway, I read it, and laughed and puzzled about what to do in strong uppers. I told Skratch that hopefully some brilliant new minds out there will figure it out and share it!

***
DJan

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Thank you for taking the time to post this information. I too have printed it out and am going to sit down and read and re-read.

We are truly lucky to have you around our DZs in Colorado.
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. May your mountains rise into and above the clouds. - Edward Abbey

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Perhaps the answer is to arrange jump run perpendicular to the uppers on high wind days.



Then the plane would be going sideways as fast as it's going forward. The same problems would be in affect... When high winds occur as upper winds, I think it is best to just give a hell of a lot more time between groups. The plane may have to go around again but so what? At least everyone lives. Let's face it, the DZO has to take some of the chance too...
Green Light
"Harry, why did you land all the way out there? Nobody else landed out there."
"Your statement answered your question."

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Perhaps the answer is to arrange jump run perpendicular to the uppers on high wind days.



Then the plane would be going sideways as fast as it's going forward. The same problems would be in affect... When high winds occur as upper winds, I think it is best to just give a hell of a lot more time between groups. The plane may have to go around again but so what? At least everyone lives. Let's face it, the DZO has to take some of the chance too...



No - a crosswind jumprun on a high wind day has some distinct advantages for separation.

Also the extra time between groups on an upwind jumprun doesn't automatically lead to a go-around since the plane gets to spend more time on jumprun anyway.

Just Physics 101
...

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

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>the problem of winds at opening altitude opposite the direction of jumprun, which would tend to decrease separation.

Thanks, I will put that back into part 1.

I wrote both parts in parallel intending part 1 to be
words and concepts and part 2 to be details and
calculations.

If you have say a 10 knot opposite lower wind that's
equivalent to a 10 knot slower aircraft ground speed
so you can just look at the next row down for the answer
instead of doing another whole table of some kind.

I didn't think many people would feel moved to read
part 2 and I was trying to make part 1 readable as
a stand alone document, but I'm going to adjust them
based on feedback.

Skr

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Hey Brian, sometimes it feels funny emailing someone
when I could just talk to them at the dropzone, but then
sometimes DJan and I email each other when she's just
20 ft away in the next room.

Modern times I guess :-) :-)

>Perhaps the answer is to arrange jump run perpendicular to the
uppers on high wind days.

Yes, or even curving up wind and then back down wind.

It's the only idea I've heard so far that addresses the really
strong uppers case.

I've heard of pilots doing this, but it seems like a much
more difficult thing to do than zeroing in on the GPS
coordinates for green light on and off.

It will be interesting to see how this plays out 10 years
from now.



>Your discussion about using the ground as a reference is right
on!

Yes, when I started everything was ground referenced,
spotting, pulling, everything. It was VFR skydiving.

Somehow it has evolved into IFR skydiving. I know some
pretty experienced jumpers who say they never see the
ground until they're open, even when they're tracking
away. One guy (3,000+ jumps) told me he looks at his
chest altimeter when he's tracking away!

I've wondered whether that is a by product of switching
to AFF as the main doorway in.



>The idea of having a GPS at the door is great except for one
drawback: If it happens to quit working, people will be lost!

Hence the need for a heads up display in everybody's
helmet :-) :-)

I don't think this is as pressing as the abyssmal lack of
canopy training but OPEC did start raising the oil prices
in 1973 and multiple groups per pass became common
within a few years after that.

So really, you'd think that after almost 30 years we'd be
further along than just "leave more time".

I think I'm losing my patience in my old age.

Skr

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***One guy (3,000+ jumps) told me he looks at his
chest altimeter when he's tracking away!

Quote

Yikes, nobody has ever collided with his own altimeter. That guy should look where he's going when he's tracking.:o Talking about all this separtion stuff, the best backup is to look down and in front on breakoff for canopies below you. Pull high, dodge them, whatever, it's the "reserve" to your "main' attempt to have safe separation. It's also hard to end up pulling low when you're seeing the whole damn planet moving up at you.:P

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Yikes, nobody has ever collided with his own altimeter.



Not entirely true - one jumper died on landing when he fell and his chest-mount altimeter came up and crushed his throat. But that's a morbid subject on an otherwise good thread. Thanks, Skratch ;)
Trapped on the surface of a sphere. XKCD

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OK - It looks like it's now sliding down the page
into finished threads so thanks everybody for the
encouragement and feedback.

On the crosswind jumprun in high uppers there
will have to be a large crab angle to maintain
a course across the ground perpendicular to the
uppers so the ground speed of the plane will be
greater than flying into the uppers but still small
enough to require more thought.

But I think this tables approach would help remove
the chaos from the low to medium range.

Skr

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***Not entirely true - one jumper died on landing when he fell and his chest-mount altimeter came up and crushed his throat. But that's a morbid subject on an otherwise good thread.
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Okay, I remember that now. And every old timer remembers being smacked in the mouth by the reserve mounted altimeter on opening. However . . . when tracking, there are better places to look, in the interest of safety, than staring at an altimeter, ya gotta agree with that, right?

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>However . . . when tracking, there are better places to look, in the interest of safety, than staring at an altimeter, ya gotta agree with that, right?

:-) :-)

I was stunned speechless when he said it, because
I knew he wasn't kidding.

Here was an S&TA, AFF instructor, been on a couple
big record attempts person looking at his altimeter while
he was tracking away.

The gap in our outlooks was just too great bridge, so I
changed the subject.

Skr

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However . . . when tracking, there are better places to look, in the interest of safety, than staring at an altimeter, ya gotta agree with that, right?



Yep - you are right. So if you guys wouldn't mind humoring a relatively inexperienced jumper for a moment, and I hope I'm not diverting the point of the thread too much.:

Ideally, on my track away, I would be looking forward most of the time (to see what I'm flying at), with an occasional glance at the ground (to check how high I am), and toward the end of the track, barrel-roll to check above me, then slow down a bit and dump.

Does that sound like a better plan than just staring at an alitimeter? It's what I do now.
Trapped on the surface of a sphere. XKCD

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