ARGH! - please help, separation questions (yet again)

[kallend 1,646]

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> I am curious to hear if those with different exit separation theories
> would both feel comfortable/safe exiting a plane with someone like
> myself.

As long as:

a) you give the sorts of times you list (5 seconds after a solo, 6-8 seconds for a larger group) and add a few second if the uppers are higher, and

b) you're willing to listen to the pilot/loadmaster/manifester/S+TA if he tells you to wait longer

then no problem. Checking for a 45 degree angle also causes you to look out the door, and that can help you see traffic, which is even better. It doesn't help you with separation, but it doesn't hurt, either - as long as you count that 5-8 seconds (more in strong uppers) before exiting.

Bill, I am uneasy with this. Information gets distorted in transmission - before long someone will say "Bill Von recommended looking for a 45 degree angle, and he's an engineer and an instructor and world record holder, so it must work."

...

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

[billvon 2,426]

>the person who told me that the 45* angle was a good idea was a
> jumpmaster who is a master rigger, been jumping for something
> like 15-20 years, is a tandem master, AFF instructor, PRO rating,
> almost 9000 jumps....someone I respect intensely.

At the 300-way, I remember running into a woman who has been jumping for about 15 years, has around 2500 jumps, and has been on several world records. She had the free ends of her leg straps wrapped around her leg pads. It looked uncomfortable.

"Hey MP," I asked, "why don't you just stow the ends?"

"They're too long," she said. "They flap in the wind."

"Why don't you double them back?" I asked her.

"Huh?" she asked. I showed her what I meant. "Hey, that's really cool! Thanks! How did you learn that? Oh, you're an instructor, you must have learned that with students."

"Uh - yeah."

Another time, a master rigger with perhaps 3000 pack jobs was hooking up a kill line collapsible. He hadn't seen one before (most of his pack jobs were on student rigs and military rigs) but he was a master rigger, so it was no problem. He hooked both lines up to the bridle attach point. After several very slow openings and one bag lock, he figured out the right way to do it.

There are a lot of really skilled people in this sport. But mastery of one area (or even several) does not equate to mastery of any others.

[elfanie 0]

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There are a lot of really skilled people in this sport. But mastery of one area (or even several) does not equate to mastery of any others.

*nods* understand and absolutely agree...

but this isn't someone who is a RW flyer who's talking about BASE jumping..

wouldn't exit order and timing be pretty basic knowledge requirements for someone with any sort of instructional ratings? (and that was actually one of the questions we were asked on our oral exam for our A...exit separation)

I did have to chuckle when the other guy said that now I could "set him straight"..
heh..just the mental picture of me walking in and saying, "I know you have 20 years on me in the sport, and I only have 40 jumps and you have every rating and license available...but someone at dropzone.com said..."

And you think that students have a hard time listening and changing?
yeah...he'll listen to me, the 40-jump-wonder.

--------------------------------------------
Elfanie
My Skydiving Page
Fly Safe - Soft Landings

[billvon 2,426]

>wouldn't exit order and timing be pretty basic knowledge
>requirements for someone with any sort of instructional ratings?

I didn't know a damn thing about exit separation when I got my SL JM rating. By the time I got my AFF rating I thought I knew, but it really wasn't any more thought out than "leave more time when it's windy." It took our DZ getting a big plane (a Beech 99) and a few close calls for me to really sit down with the other JM/I's and talk about spotting and separation issues. None of that stuff was covered in any instructional course I ever took, or taught. Maybe that's an oversight.

[DBCOOPER 1]

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Maybe that's an oversight

No maybe about it.

Replying to: Re: Stall On Jump Run Emergency Procedure? by billvon

If the plane is unrecoverable then exiting is a very very good idea.

[billvon 2,426]

>No maybe about it.

The question isn't what do you cover, it's what do you leave out. In a 3-day ICC, you can't cover ATC operations, demo jumps, ops on all aircraft, exit separation under all conditions, first-responder medical care, teaching technique, common student problems, unusual student problems, liability issues, basic rigging, teaching leg turns vs arm turns, spotting, how to fly your canopy, how to _teach_ someone else to fly theirs, how to help them downsize, whether floating vs poised AFF exits are better, equipment problems with small women, jump runs where wingsuits get out first and last, landing on snow, use of weights on students, transition training after graduation, transition between different programs, transition between different gear . . .

You can cover some of that, even most of that. The trick is to know what's important and what's not. Heck, I could fill a notebook with things it might be nice for instructors to know. Unfortunately, few people can afford to take three weeks off from work to attend an ICC. Instead, you have to assume that people who have been JM's for a year have a basic skill set. You have to assume they can land their own canopies, and after handling students for a year, you have to assume they can pull off a good AFF exit, can spot, know what exit order to use etc. That means that if someone shows up at an ICC that doesn't know how to land their canopy, they're not going to learn it, and they will be bad canopy coaches. Were I to re-teach an ICC today, the thing I'd concentrate on would be canopy control instruction, because that's what's killing people nowadays.

When I was teaching ICC's, the progression was generally SL-JM, AFF-JM, AFF-I. That was three courses - the SL one, which was quick and dirty, the AFF one, which was rigorous, but covered JM rather than instructor skills, and the ICC, which covered how to teach. Nowadays most instructors get two courses, the BIC and the JCC. That's _less_ time to cover the same material. I'd be all for spending two hours on exit separation, but if they had time to cover either exit separation in depth or canopy control instruction in depth (but not both) I'd vote for going quick on the exit separation, and spending the time on canopy control.

[AndyMan 7]

No, but you can put it in the IRM.

Unfortunately, there really isn't any useful information for instructors in the IRM, so I don't know why they'd start now...


_Am

__

You put the fun in "funnel" - craichead.

[DBCOOPER 1]

BIC is history.Only thing its good for now is a long break during the coaches course while they spend 1.5 hours covering what took 2 days in the BIC.Might be a good thing to cover in the coaches course.

Replying to: Re: Stall On Jump Run Emergency Procedure? by billvon

If the plane is unrecoverable then exiting is a very very good idea.

[saramorgan 0]

Hey- relax! When you stick your head out of the plane, you should see the group that just left @ a 45 degree angle before you leave. True there are a lot of variables, but try to keep it simple.

[billvon 2,426]

>When you stick your head out of the plane, you should see the
>group that just left @ a 45 degree angle before you leave.

That does not work. If you use that method, you risk injuring or killing the people in the previous group through collisions at opening time. Ask the pilot, a JM on the plane, manifest etc if you are unsure of how much time to leave between exits. That's better than relying on a method that tells you nothing about separation at opening time.

[bmcd308 0]

>>If you use that method, you risk injuring or killing the people in the previous group through collisions at opening time.<<

More likely, you risk pi$$ing off the pilot as you wait all day for them to fly their canopies far enough behind the plane that they are at a 45 degree angle. It has always appeared to me that with the exception of right out the door, the groups are falling down much faster than they fall behind the aircraft.

----------------------------------
www.jumpelvis.com

[billvon 2,426]

>More likely, you risk pi$$ing off the pilot as you wait all day for them
> to fly their canopies far enough behind the plane that they are at a
> 45 degree angle.

I agree; however, people use the "45 method" all the time and don't wait 60 seconds between groups. This indicates that they do not use the 45 degree angle method, but instead use a method that they _think_ results in a 45 degree angle. Which means it's pretty much anyone's guess when they get out.

Bill's project when I get back from Thailand - set up a video camera pointed at exactly 45 degrees from the horizontal out the door, and film a whole load getting out. Capture the images and show what really does happen.

[kallend 1,646]

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>More likely, you risk pi$$ing off the pilot as you wait all day for them
> to fly their canopies far enough behind the plane that they are at a
> 45 degree angle.

I agree; however, people use the "45 method" all the time and don't wait 60 seconds between groups. This indicates that they do not use the 45 degree angle method, but instead use a method that they _think_ results in a 45 degree angle. Which means it's pretty much anyone's guess when they get out.

Bill's project when I get back from Thailand - set up a video camera pointed at exactly 45 degrees from the horizontal out the door, and film a whole load getting out. Capture the images and show what really does happen.

Hey - I was going to do that!

I already have an inside the door shot of a 10-way speed (no show) exit leaving, but unfortunately no angle reference. It's pretty obvious that the angle hardly changes, and its less than 45 degrees.

...

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

[skr 1]

>wouldn't exit order and timing be pretty basic
>knowledge requirements for someone with any
>sort of instructional ratings?

It should be common knowledge for everybody,
but it seems to be harder to get that established
than anybody would have believed when we
first started talking about this about four million
ascii tons of discussion ago :-) :-)

I think one reason it's confusing is that our
intuition about how things work when you jump
off of something developed for limited situations
like jumping off of a chair.

If it's right under me I will land on it, but if it's
over there at a 45 degree angle I'll miss it.

That intuition doesn't work when you have
upper winds and forward throw and 60 seconds
worth of freefall drift and hundreds of feet of
canopy motion from the group in front of you.

It gives you wrong answers and what we have
to do is make the effort to expand our intuition
to this new, more complicated situation.

I wrote something about that once. Go to

http://indra.net/~bdaniels/ftw/index.html

and go down to the bottom in the learning section
and look at "Learning how to do Separation" at

http://indra.net/~bdaniels/ftw/sg_skr_coach_weekend.html#septop


I found John Kallend's freefall simulator pretty
helpful in expanding my intuitive feel for how
it works. And I agree with billvon's way of
formulating it, he's been part of this discussion
for 10 or 12 years.

Skr

[DBCOOPER 1]

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"Don't hose the last groups out" translates to "Just kill the people
in the first ones instead".

Amen.

Quote

when we first started talking about this about four million ascii tons of discussion ago

There are a lot of newbies
Would rather beat a dead horse then bury a skydiver.
Very well written and informative.
I think it should be posted with the other Safety & Training:Exit articles.

Replying to: Re: Stall On Jump Run Emergency Procedure? by billvon

If the plane is unrecoverable then exiting is a very very good idea.

[saramorgan 0]

So are you saying that the 45 degree angle is actually unattainable, it may look like the previous group is 'there', but they slide down the hill & then start dropping straight down? What would be a better way to explain in a simple way the separation issue? That we want enough sep. that each group can turn & track for 5 sec. without getting in someone else's airspace... That standard count out of an Otter is 5, out of a CASA is 3, and if the uppers are strong the add more on top of that? Thanks, I'm learning , I am trying to keep it simple.

[billvon 2,426]

>So are you saying that the 45 degree angle is actually unattainable,
> it may look like the previous group is 'there', but they slide down
> the hill & then start dropping straight down?

Well, yes, but they never quite reach that 45 degree angle. 30-35 degrees is more like it.

>That standard count out of an Otter is 5, out of a CASA is 3, and if
> the uppers are strong the add more on top of that? Thanks, I'm
> learning , I am trying to keep it simple.

Basically. In order of accuracy, you can use:

1. Wait X seconds before groups, and add time if the headwinds are strong or groups are large. (5 seconds for an otter in no winds is absolute minimum.)

2. Calculate it. Sneak a look at the pilot's GPS; look for ground speed in knots. Multiply by 1.7. That's the number of feet you will move over the ground every second. At 80kts groundspeed, you cover ~140 feet per second. Want 800 feet between groups? (a reasonable number) Then wait 7 seconds.

3. Do the exhaustive calculation. Figure out the plane's groundspeed. If the winds at opening altitude are from the opposite direction, _subtract_ them from the plane's speed. This gives you actual separation at opening time, assuming people fall straight down. At the same 80kts from the above example - if the winds at 3000 feet are from the opposite direction at 20kts, then you're really only covering 100 feet per second, relative to where you'll be at opening time. So you have to wait 8 seconds to get 800 feet.

(You can also use vector calculations to determine what to do if there's a quartering tailwind at opening altitude, but that's a bit hairy.)

What most DZ's do, in my experience, is to use method 1 and see how it goes. If people open up too close, they add a little more time. It's basically trial and error, and that works for places that can afford to be conservative (i.e. just leave a lot of time and take a second pass.) At places like the WFFC, you have to be a little more careful since second passes are generally not possible, and there are a lot of people in the air.

[saramorgan 0]

That's what I learned @ my home DZ. Where I am now, it's always 'What's the separation?". So I look& count @ the same time. It can be hard sometimes to re- think the basics that I was taught. I am glad I said something , this is how we learn!

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