Separation Anxiety

[UKKid35 1]

Shortly after gaining my A licence I found myself on a load where I was last to exit. This was my first time not having someone tell me when to exit. I don't ever hesitate to exit, I'm always very eager to get out, but I was also keen to ensure that I maintained separation and started counting the ten seconds after the last group exited. After about three seconds the pilot started shouting at me to jump, I stubbornly continued until about seven seconds after which I gave in to the shouting from the pilot.

I checked with the JM both before and after the jump that I was correct to leave ten seconds separation. I wish I'd asked the pilot why he was so keen to get me out, but at the time I thought that asking the JM should have been enough.

What should I have done in the air, and what should I have done afterwards?

[speedy 0]

Sadley, you will find that on any one load, that only a very small percentage of the jumpers have any clue on how to calculate how much seperation is needed.

If you want to learn more, look at the information on John Kallends web site.
http://www.iit.edu/~kallend/skydive/#resources
Of particular interest is the Powerpoint presentation on separation with freefall sim.(updated 3/2004).

Dave

Fallschirmsport Marl

[pilotdave 0]

Shoulda given the pilot some spotting directions while he was yelling at you.

When you're last out (or any time), don't forget to check the spot before leaving... you could be really long. The pilot might have wanted you to get out ASAP so he wouldn't have to do a go around for you or something. But landing off beats a freefall collision any day.

And I was told to use the 45 degree rule AGAIN last weekend. When will the old timers learn??

Dave

[FrogNog 1]

Seems weird to me that the pilot would yell at the last jumper to get out. I don't see how the last jumper hanging around for another 15 seconds would hurt the pilot any.

And the nice thing about flying jumprun into the wind is long spots are upwind, and opening higher can usually deal with it.

Now, not all jump runs are into the wind, for various reasons. And opening higher, even when last out of the plane, has its safety issues. But I'll take a long spot over insufficient exit separation any day. (Note that my jumps tend to be small groups, and I habitually open near the top of the standard acceptable range.) And I still don't get the pilot yelling at the last jumper to get out.

Maybe he realized the freefliers had all gone so someone else had to do their job.

-=-=-=-=-
Pull.

[BIGUN 1,075]

You did the right thing. The pilot ain't jumping - you are. I know I'm gonna catch some $h!t for this, but my rule is; the pilot has control of the aircraft until the door is open. Once that door comes open, jump safety becomes my responsibility.

I remember a time when pilots worked with the jumpers rather than with the GPS.

Nobody has time to listen; because they're desperately chasing the need of being heard.

[BigH 0]

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Sadley, you will find that on any one load, that only a very small percentage of the jumpers have any clue on how to calculate how much seperation is needed.

If you want to learn more, look at the information on John Kallends web site.
http://www.iit.edu/~kallend/skydive/#resources
Of particular interest is the Powerpoint presentation on separation with freefall sim.(updated 3/2004).

Very interesting presentation
Question: I understand why a solo free flyer has less freefall drift than a solo flat flyer but why does the free flyer have more forward throw when they exit the plane?

[speedy 0]

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why does the free flyer have more forward throw when they exit the plane?

Generally, when free fliers exit they do not present as much surface area to the relative wind as belly fliers. Therefore, the speed they have from the plane flying forward is not reduced as quickly leading to more forward throw.

Dave

Fallschirmsport Marl

[peregrinerose 0]

I had the same issue. Was leaving the plane second though, my husband was first, it was my first jump without an instructor with me. As soon as I hit the door (and I was right on my husbands ass, no delay in me getting there) the person behind me was telling me to jump, I waited another 4. It was a minimal wind day, but I'm too new to want to be all that close to another jumper at this point. It wasn't a full load, so plenty of time for others to get out as well.

The way I see it, it is my jump, that extra 4 seconds wouldn't delay others much. My husband is lucky to hit 100mph in freefall, I am closer to 120. The last thing I need is to be a new jumper and be in a freefall collision with my husband who is also fairly new (50 jumpsish).

Jen

Do or do not, there is no try -Yoda

[funks 1]

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You did the right thing. The pilot ain't jumping - you are. I know I'm gonna catch some $h!t for this, but my rule is; the pilot has control of the aircraft until the door is open. Once that door comes open, jump safety becomes my responsibility.

I remember a time when pilots worked with the jumpers rather than with the GPS.

Then why is it in emergency situations if the pilot says to get out...you get out.....In this case how do you know there was not some sort of emergency? I do understand that ultimately we are responsible for ourselves, however i have seen discussions where people agree that if the pilot says to get out, you get out.....thoughts?

also...the poster originally said that the pilot was continuously yelling at him....that would lead me to believe something was wrong. If it was just a matter of separation time i think the jumper should have gotten out...if there was traffic below or some other reason not to get out then he did the right thing. Otherwise, i personally think he should have gotten out and then brought the issue up with the DZO or S&TA.

[pilotdave 0]

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Once that door comes open, jump safety becomes my responsibility.

I partially agree, but it's still a team effort. The pilot can see and hear things you can't, and you can see and hear things the pilot can't. We all have to work together to do this safely.

Where I jump, the pilot uses GPS to put the plane (Super Otter) onto the jumprun. Red light comes on a couple miles early, and green light comes on when the pilot believes it is safe to jump, but NOT necessarily over the correct spot. We do the spotting ourselves, and decide when to jump. But the pilot is far more aware of traffic in the area and ATC issues that the jumpers don't know about. So no green light, no jump, no matter how perfect the spot is. And that can include the light shutting off mid-jumprun.

Dave

[BIGUN 1,075]

I like your style. How does the pilot communicate forecasted winds aloft vs. actual winds aloft so the jumpers know what the separation should be?

Nobody has time to listen; because they're desperately chasing the need of being heard.

[BIGUN 1,075]

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In this case how do you know there was not some sort of emergency? I do understand that ultimately we are responsible for ourselves, however i have seen discussions where people agree that if the pilot says to get out, you get out.....thoughts?

also...the poster originally said that the pilot was continuously yelling at him....that would lead me to believe something was wrong. If it was just a matter of separation time i think the jumper should have gotten out...if there was traffic below or some other reason not to get out then he did the right thing. Otherwise, i personally think he should have gotten out and then brought the issue up with the DZO or S&TA.

Green light = jump
Red light = No jump

When no lights, DZO's, S&TA's, Instructors, and skydivers need to have an SOP regarding verbal commands.

For example:

Skydive! Jump!, etc. could mean your free to go.
Stop!, Stop!, Stop!! could mean don't jump.

EMERGENCY EXIT!!!
EMERGENCY EXIT!!!
EMERGENCY EXIT!!!

Means get the hell outta the plane.

Nobody has time to listen; because they're desperately chasing the need of being heard.

[winsor 187]

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I like your style. How does the pilot communicate forecasted winds aloft vs. actual winds aloft so the jumpers know what the separation should be?

Winds aloft have more of an effect on spotting than separation. Check out John Kallend's simulation to see what I mean.


Blue skies,

Winsor

[BIGUN 1,075]

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actual winds aloft so the jumpers know what the separation should be?

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Winds aloft have more of an effect on spotting than separation.

If spotting for the release point, then separation would have the same effect.

Nobody has time to listen; because they're desperately chasing the need of being heard.

[winsor 187]

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actual winds aloft so the jumpers know what the separation should be?

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Winds aloft have more of an effect on spotting than separation.

If spotting for the release point, then separation would have the same effect.

No.

Spotting is a three-dimensional problem, but separation is four-dimensional. For spotting you only need to know where, but for separation when is important.

It has been done to death. Please review enough of the readily available materials that it sinks in, since it is important for safety and you don't quite get it.


Blue skies,

Winsor

[BIGUN 1,075]

I did not expand enough on my last statement and if you're saying that I miscommunicated, that's one thing. If you're saying that winds aloft do not have an effect on both spotting and separation, then we have a disagreement.

However, no disagreeement need be left on the note of the belittling comment as the one made here.

You may view it as an opportunity to correct me if I am wrong or an opportunity to engage in educational debate. But, you may not take it as an opportunity to denigrate.

Nobody has time to listen; because they're desperately chasing the need of being heard.

[winsor 187]

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I did not expand enough on my last statement and if you're saying that I miscommunicated, that's one thing. If you're saying that winds aloft do not have an effect on both spotting and separation, then we have a disagreement.

What you said was;

"If spotting for the release point, then separation would have the same effect."

That is wrong.

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However, no disagreeement need be left on the note of the belittling comment as the one made here.

My point is that what you said displays a fundamental lack of comprehension. Rather than discuss it here, the most effective way for you to come up to speed is to review some of the very good material covering the subject. It's out there and available.

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You may view it as an opportunity to correct me if I am wrong or an opportunity to engage in educational debate.

As I have said before, physics is not subject to solution by quorum. What's to debate?

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But, you may not take it as an opportunity to denigrate.

I do not wish to hurt your feelings. I would like it if you would do your homework before holding forth on this subject.


Blue skies,

Winsor

[BIGUN 1,075]

You are correct that I said, "If spotting for the release point, then separation would have the same effect." And, that was probably my fault for not expanding enough.

And, since you haven't addressed my comment that winds aloft have an effect on both spotting and separation, I am assuming that we are in agreement.

Everything else is then apparently moot. Including my need to break out the numerous books regarding the physics, math, and qualitative experience from the myriad of skydiving professionals I've come to know over the years - including yourself. And for what you've taught me and for our discussions, I thank you.

Nobody has time to listen; because they're desperately chasing the need of being heard.

[vibeke 0]

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If you want to learn more, look at the information on John Kallends web site.
http://www.iit.edu/...d/skydive/#resources

I cant find this website - link appear to be broken. However others seem to find it with out trouble?
Can anyone provide me with a throughout written link or perhaps an other link to the same presentation?!
Thank you.

[winsor 187]

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since you haven't addressed my comment that winds aloft have an effect on both spotting and separation, I am assuming that we are in agreement..

For the record, no, we are not in agreement. Winds aloft, in and of themselves, have nothing in particular to do with separation.

If you want to consider separation at opening altitude, the relevant parameter is airspeed with regard to winds at opening altitude. Groundspeed (like from the GPS) plus the magnitude of winds at opening altitude (the headwind component, at least - it's actually vector subtraction) gives you this value.

Rather than rehash the whole thing again, or have you spend a semester studying Kinematics, you would do well to simply do a search on the subject on DZ.com.

Be advised that many people put forth physical models therein that are complete hogwash. A good rule of thumb is that if they disagree with John Kallend, they're wrong (I'm serious).


Blue skies,

Winsor

[BIGUN 1,075]

http://www.iit.edu/~kallend/skydive/

Then click on; "Downloadable freefall modeling program for Windows"

It's a great tool "to determine the most likely trajectories of (groups of) skydivers with different fall rates, given the fall rate, airplane speed, and winds." (Kallend)

Nobody has time to listen; because they're desperately chasing the need of being heard.

[sundevil777 94]

I don't have powerpoint, so can't check out Kellend's simulator.

As jumprun groundspeed approaches 0 (really high winds), the opening point for jumpers with the same fall rate becomes the same, correct? I don't want the small bit of drift you get by winds at opening to be what provides separation. Groundspeed of 0 is of course extreme, but I think it proves the point.

I'm sure I'll be corrected if I'm wrong, but isn't this why in general we increase the time separation if a jumprun is flying into high upper winds? Isn't this an argument for crosswind jumpruns, so that we don't have to remember to increase the time between groups?

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[winsor 187]

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I don't have powerpoint, so can't check out Kellend's simulator.

As jumprun groundspeed approaches 0 (really high winds), the opening point for jumpers with the same fall rate becomes the same, correct? I don't want the small bit of drift you get by winds at opening to be what provides separation. Groundspeed of 0 is of course extreme, but I think it proves the point.

Not hardly. With sufficient uppers, everyone can exit at one over the ground and open at another point over the ground - and still have plenty of horizontal separation!

How's that, you ask?

Simple. Remember those winds we mentioned before? They are busily blowing the first group downwind long before the next group gets there. It's only when you try to occupy the same place at the same TIME that things get dicey.

If you throw in the extra dimension of time, you get a different picture.

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I'm sure I'll be corrected if I'm wrong, but isn't this why in general we increase the time separation if a jumprun is flying into high upper winds?

No, it's more like why a dog licks his balls - because he can.

If you have the opportunity to take more time between groups and still get back, by all means use it.

About the only factor that dictates a longer delay with more headwind is the difference between winds at exit altitude and winds at opening altitude. That's where the groundspeed plus winds at opening altitude (minus if the directions are opposite) comes in.

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Isn't this an argument for crosswind jumpruns, so that we don't have to remember to increase the time between groups?

No.


Blue skies,

Winsor

[UKKid35 1]

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I don't have powerpoint, so can't check out Kellend's simulator.

You can download Powerpoint Viewer free here:

http://www.microsoft.com/downloads/details.aspx?FamilyID=428d5727-43ab-4f24-90b7-a94784af71a4&displaylang=en

[BIGUN 1,075]

Download Kallend's, "Downloadable freefall modeling program for Windows" and replicate the parameters in the attachment.

Nobody has time to listen; because they're desperately chasing the need of being heard.