What do you say when people use 45 degree rule or try to get others to use it?

[MisterCrash 0]

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What I look for is how fast the previous (before next) group is shifting (with knowledge of the upper winds) and get out accordingly.

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And it would have to be one heck of a difference for you to see it with the eye.

So what you are saying is you jump out blind? There is a big shift difference when the plane has low or high ground speed because of high or low upper winds. I have seen relative groups stay underneath the plane for ages and I've seen them move along nice and smooth. The difference is not hard to notice. A machine has no brain and doesn't tell you when it has a wrong reading. My eyes don't lie.

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Where are you jumping that your students are not being supervised in the plane?

I won't say they didn't get the briefing. I wasn't in their classes. But what I do know is that at our dropzone freefly exits after flat (for the same reason of horizontal seperation theory) and experienced jumpers have the responsability to make shure student-graduates respect the seperation. Do you have an instructor staying by the door every time to drop AFF graduates? I don't think so.

Ask any AFF graduate to explain the exit order and seperation in detail, and many will fail to do so. That is why people come up with stuff like 7 seconds and 45 degrees. To be done with it the easy way...

I think RW jumpers should be happy to have freeflyers check students exit seperation. Unless offcourse you trow out the graduates last and hope they follow the rules. Because I'm not a big fan of hoping.

All speeding past collide and crashing, I'm in paradise.

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[DanG 1]

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Do you have an instructor staying by the door every time to drop AFF graduates? I don't think so.

You think wrong. We have at least a Coach supervise all pre-license jumpers up to exit. That includes checking exit separation (as well as other things that aren't being discussed here).

That's how it is supposed to be done. It's not hard at all to achieve. Often times one of the tandem videographers who is also rated will supervise students. If no one on the load is qualified, we put someone on the load to handle it.

If your DZ is not doing that, they are selling their students short.

- Dan G

[kallend 1,621]

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What I look for is how fast the previous (before next) group is shifting (with knowledge of the upper winds) and get out accordingly.

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And it would have to be one heck of a difference for you to see it with the eye.

So what you are saying is you jump out blind? There is a big shift difference when the plane has low or high ground speed because of high or low upper winds.

That is simply not true. Physics says it's not true. Experiment says it's not true. In conclusion, it's NOT TRUE.

...

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

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[billvon 2,380]

> I have seen relative groups stay underneath the plane for ages and I've seen
>them move along nice and smooth.

No, you haven't, unless you were exiting a balloon. A given group will look exactly the same whether the plane is flying into 100kt winds or flying with 100kt winds.

Now, that's not to say that you can't tell what's going on by looking out the door. You can, for example, see the airplane's ground speed. You can see exit separation in most cases by looking directly at the ground. Put people out 1000 feet apart (according to where you are over the ground) and in most wind conditions you will get good separation at opening time.

However, that's because you're looking at the ground, not because you're looking at the people who just got out. They always look the same.

>My eyes don't lie.

Apparently they do. However, cameras don't lie; let me know if you'd like the pictures that prove the above.

[peek 20]

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However, cameras don't lie; let me know if you'd like the pictures that prove the above.

Bill, I'm thinking the article in that post needs a permanent home. By all means point us to the post you first made after your research, or post them again.

[MisterCrash 0]

I found it myself: http://www.dropzone.com/content/Detailed/628.html
Will review my own theorie, but I still think going out blind counting separation is a bad thing.

All speeding past collide and crashing, I'm in paradise.

[chuckakers 369]

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I have seen relative groups stay underneath the plane for ages and I've seen them move along nice and smooth. The difference is not hard to notice. A machine has no brain and doesn't tell you when it has a wrong reading. My eyes don't lie.

Good grief.

Chuck Akers
D-10855
Houston, TX

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[popsjumper 2]

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suggestions?

Tell 'em they're wrong and that it's actually closer to 50 degrees.

My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

[BIGUN 1,049]

Show them Professor Kallend's trajectory model

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

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

[pilotdave 0]

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What do you say when people use 45 degree rule or try to get others to use it?

Unfortunately when you hear it, it's probably not a good time for a conversation about physics, computer animations, or something you read on the internet. Usually it's on a loud jump plane. And usually it's being used by someone that doesn't want your advice. He knows what he's doing.

I can only remember hearing anyone actually recommend it in real life a few times. One was an AFF instructor teaching his student on the ride up at a DZ I was visiting. Not touching that. Wrong time, wrong place.

Another time it was an old jumper organizing a newbie group at a boogie in FL. He explained it to my group, getting out behind his group, as we were boarding the plane. Why bother trying? Wasn't going to work. His group was getting out first anyway. My friend and I just agreed we wouldn't try to combine our groups later in the day like we had been considering.

The good news is that, at least in my experience, it doesn't come up often. Thanks to the internets.

Dave

[Jumpah 0]

It had been a while since the last huge thread on this worn topic. I was wondering what was going on

Here's an attempt...instead of telling them they've been doing it wrong for years and years, show them the new method and why it has advantages.

[strop45 0]

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There is a big shift difference when the plane has low or high ground speed because of high or low upper winds. I have seen relative groups stay underneath the plane for ages and I've seen them move along nice and smooth. The difference is not hard to notice. A machine has no brain and doesn't tell you when it has a wrong reading. My eyes don't lie.

This is the essential problem. It seems that a great number of people have convinced themselves that they are seeing the 45 degree rule work under all sorts of circumstances. This makes discussion a waste of time.

Just because it doesn't work in practice, doesn't mean it can't be made to work into theory.

The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

[pilotdave 0]

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Just because it doesn't work in practice, doesn't mean it can't be made to work into theory.

I'd say it's the opposite. It works in practice, but not in theory. It only works because people attempting to use it happen to wait enough time for adequate separation most of the time. If it didn't work in practice, we'd have seen way more collisions or near-collisions. So it works as well as counting the planes parked on the airport or the fleas on the dropzone dog.

Dave

[rhys 0]

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: >45 degree rule is a bit better than nothing.

Well, sort of. If you actually use the 45 degree rule you won't get out, ever.

So not only does the 45 degree rule not work, the people who use it don't even understand it. So who knows what they're actually doing?

I will assume that most of the people that 'bash' the 45dgre thing and say it is crap and all this stuff without explaining a better system, have never jumped between 40 and 50 degrees lattitude?

example;

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At best it's wrong. At worst, it could lead to inadequate separation. It is not better than nothing.

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In Reply To
suggestions?

Tell 'em they're wrong and that it's actually closer to 50 degrees.Wink

and comments like these;

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The group ahead of you will only "shift" at a different rate if there is a difference in the wind speed at the aircraft's altitude and the group's altitude. And it would have to be one heck of a difference for you to see it with the eye.

Lead me to believe these strong advocates/postwhores have no experience with strong upper winds.

The sad thing about this conversation is that the origional poster is in New Zealand and will most likey be subject to strong upper winds on a daily basis.

when I say strong I mean strong like up to 50knots+ at altitude.

most posters here have never been near the 45degree south latitude (Roaring forties) where these type of winds are prevelant yet wish to be outspoken about such exerience.

I have many (over 2500) of my jumps in Queenstown, New Zealand and around that town which is smack bang at 45 degrees lattitude, smack in the middle of the roaring forties.

Let me tell you nay sayers, there has been plenty of times where we have had to wait for at least 45 seconds on a jumprun between exits (12000' jumps), the aircraft (cresco, cessna 185, porter) has been stationary due to thier slow run in speeds and similar speed upper winds.

In this situation the group in fact does stay directly below you, waiting any less time would put you in serious danger.

When we (my wife and I) come to tropical climates, the dz staff wonder why we are so concerned with upper winds and laugh at us as though we are amateures! But from time to time, even in the tropics, strong upper winds can be there, and these guys still pile put on top of each other like lemmings.

The origonal poster deserves a better description than what has been given, bickering between one another to prove a point, inflate an ego or increase post numbers is doing nothing for the safety of the person that needs this information the most.

For the OP,

If your DZSO or CSO requests that you use this rule, I suggest you do so. although 45 degrees might never happen as explained in various hypothesies, a good shift in the position of the previous group towards the tail indicates adequate separation is being achieved.

Never rely on counting alone, use your eyes and your instincts as well.

In New Zealand winds can change abruptly (as I am sure you are aware) and the uppers play a strong role in what happens in the big picture, when the uppers are so strong, it usually indicates the weather is going to change, the wind on the ground will usually increase significantly not long after strong upper winds are recorded, but sometimes though it can be 60 knots at 12000 and 8 knots in the landing area all day long.

Be safe, be aware and listen to the experienced jumpers from 'your regon', they have the most knowledge of what happens at your dz.

Have fun while doing so!

"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

[pilotdave 0]

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Let me tell you nay sayers, there has been plenty of times where we have had to wait for at least 45 seconds on a jumprun between exits (12000' jumps), the aircraft (cresco, cessna 185, porter) has been stationary due to thier slow run in speeds and similar speed upper winds.

In this situation the group in fact does stay directly below you, waiting any less time would put you in serious danger.

No, they don't stay directly below you. It's just that your path through the sky will be very close to their path through the sky if you exit too close to them. Watching them will not tell you anything about how long to wait. I don't see how 45 seconds would ever be necessary considering the group in front of you will likely open 45 seconds before you and fly away in strong wind. But assuming no canopy drift, yes, it might take 45 seconds for the plane to move far enough to separate the groups. But you still can't tell anything by watching the group in front of you. Point is that you can calculate that 45 seconds you need between groups on the ground before you get in the plane.

Dave

[brettski74 0]

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Let me tell you nay sayers, there has been plenty of times where we have had to wait for at least 45 seconds on a jumprun between exits (12000' jumps), the aircraft (cresco, cessna 185, porter) has been stationary due to thier slow run in speeds and similar speed upper winds.

In this situation the group in fact does stay directly below you, waiting any less time would put you in serious danger.

You're deluding yourself. The only way an exiting jumper will stay directly below you is if the aircraft from which you launch is horizontally stationary within the air mass. Untethered balloons are excellent at this. You could also get this situation if you exit from a helicopter that is hovering stationary within the air. Despite your post, New Zealand is not the only place in the world to experience strong upper winds, nor are you the only person to have jumped in strong uppers.

The upper winds tell you how fast the air mass at a particular altitude is moving with respect to the ground. Since neither you nor the aircraft are tethered to or pushing off the ground in any way, this has absolutely no effect on your trajectory with respect to the aircraft once you leave. If I exit from a Twin Otter doing 85 knots IAS, it will look pretty much the same from the door of the aircraft whether the upper winds are doing 10 knots, 50 knots or -200 knots. It will look different to an observer on the ground, for sure, but that's because they are tethered to the ground and the body of air through which I'm falling is moving with respect to them and therefore pushing me horizontally with respect to them.

But you jump from slower flying aircraft, you say. Great! Finally something that *will* make a difference to what you observe in the door. If you jump from a slower moving aircraft, you will appear to fall away from the plane more steeply, but again, absolutely nothing to do with the upper winds and everything to do with the aircraft's indicated air speed.

[pirana 0]

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>45 degree rule is a bit better than nothing.

Well, sort of. If you actually use the 45 degree rule you won't get out, ever.

So not only does the 45 degree rule not work, the people who use it don't even understand it. So who knows what they're actually doing?

Not true at all. Eventually, the group before you will acheive 45 degrees. Probably about 15 seconds after they deploy.

" . . . the lust for power can be just as completely satisfied by suggesting people into loving their servitude as by flogging them and kicking them into obedience." -- Aldous Huxley

[billvon 2,380]

>Lead me to believe these strong advocates/postwhores have no experience
>with strong upper winds.

You'd assume wrong. There are places other than New Zealand that have very strong winds. Case in point -

A few weeks ago I had to spot a load into a very tight area that had a 20kt wind coming out of the west at ground level and a 46 knot wind coming out of the south at 12000 feet. I watched the first group exit from the lead plane in those winds - and they followed exactly the same trajectory they always follow. Winds don't affect people when they get out of the plane, because the winds THEY feel are always the same (80 knots coming from the nose of the plane.)

Years back during Santa Ana conditions in San Diego we'd have 50kt winds out of the east at altitude and 10kt winds out of the west at ground level before they switched. This is the absolute worst case; your separation is reduced even further by the contrary ground winds. Even with a fast airplane (a King Air) we had to leave 30-40 seconds between groups. And in every case, the exits _looked_ exactly the same.

One day at Otay I outfitted an Otter with cameras and had them run upwind and downwind jump runs. If there's a difference, surely it would be very clear in those pictures. Once again, no difference.

>In this situation the group in fact does stay directly below you . . .

No, it doesn't, unless you are in a balloon.

Think about what you're saying. Are you saying that, if you threw a paper bag out the door on jump run, and the winds were 80kts on the nose (i.e. the plane had zero ground speed) the paper bag would fall straight down? If the winds were 90kts, and a group exited, would the group end up in FRONT of the airplane from your perspective?

No. From the perspective of the guy in the door, the paper bag gets blown backwards like it always does, and those groups exit and get blown backwards about the same amount every time.

The 45 degree rule does not work, period. It does not give you any useful information about what the winds are doing. It does not tell you how much separation you need. If you use it correctly, you will never get out. If you use it incorrectly, you'll get out at a random time that has nothing to do with winds.

Now, it may well end up providing adequate separation, because people who use it may think "wow, the winds are 46 knots! I better look at them a long time before exiting!" If so, great - they are using timing-based exit separation (which does work) and just calling it something else. That's fine, as long as they always leave enough time, and they wait longer the stronger the winds are.

But if you say "I'm going to wait until the group before me makes a 45 degree angle, and then go" or "I'm going to see if you get blown back" - then you'll be exiting before our group. Not because of a silly internet argument, or a desire to "prove" anything to anyone, but because incompetence in this sport can kill - and I'm going to try to avoid that outcome with my group.

[billvon 2,380]

>instead of telling them they've been doing it wrong for years and years,
>show them the new method and why it has advantages.

I have done that several times. Usually their response is "that's great, thanks, but the 45 degree rule is simpler and I'm used to it."

[pchapman 261]

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Let me tell you nay sayers, there has been plenty of times where we have had to wait for at least 45 seconds on a jumprun between exits (12000' jumps), the aircraft (cresco, cessna 185, porter) has been stationary due to thier slow run in speeds and similar speed upper winds.

In this situation the group in fact does stay directly below you, waiting any less time would put you in serious danger.

I agree that this makes little sense.
The closest it can come to working, is if one is talking about open canopies down low in an area of low wind, behind the aircraft.

Then the plane may be crawling across the ground in the high uppers, upwind of the DZ, canopies open up over the airfield, and stay there in the low lower winds. Since the high uppers are only experienced during freefall, the spot isn't all that far upwind, so the airport is relatively close to 'below'. So yes a long time between exits is needed which matches modern theory (ground speed minus lower wind speed is very low). But as they exit the groups are still going to going far behind the plane.

(Or do late divers on speed stars in strong New Zealand winds somehow all have to dive straight down?!)

[JohnMitchell 14]

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If as a freeflyer, I get a student in front of me (who hasn't gotten any separation briefing), I don't have the time and resources to brief him inside the plane.

The guy leaving ahead of you is not a hazard to you. The guy behind you is.

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What I think is best is to have them look outside,

And what is he looking for??

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visually follow the group in front of him and checking with me, or with another experienced jumper before exiting.

What are you basing your "go" decision upon?

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I tend towards the 45 degree rule myself, even if it has been proven that they never get to 45 degrees. It's just a name fella's. It has more effect than sayin' 7 seconds maty! Cause a nervous student counts FAST!

So you use a rule you know is proven false? What's wrong with teaching what works, and teaching the student to count aloud "1-1000, 2-1000, etc."?

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What I look for is how fast the previous group is shifting (with knowledge of the upper winds) and get out accordingly. The knowlegdge of the upper winds gives you an estimate on how long to wait, but you still have to LOOK!

Once again, what are you looking for?

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If somebody is telling a student to wait 7 seconds, it is just to save their own ass and not explain how exit seperation works.

What's wrong with saving some asses?

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And it always seems to come down to the freeflyers trying to brief students about horizontal separation, not to kill the relative guys.

I think I do a pretty good job as a relative worker briefing exit separation, both on the ground and in the air. Drop by on Safety Day and I'll give you the long version.

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Because we have to make shure they wait long enough and we get to see sometimes how fucking fast they get out.

So it's a time thing after all?

45 degrees or 7 seconds, they are both wrong (but used when there is no time for briefing). The 'right thing' is a 30 minutes briefing on exit order and horizontal separation. Which should happen BEFORE the first solo jump.

[Reginald 0]

This is why I get a laugh at the discussions of exit separation. It’s almost like someone mentioning a communist in the early 50’s or health care reform at a town hall meeting today, or throwing a litter of kittens into chummed, shark infested waters.

I state "If the previous group has not moved sufficiently over the ground (which is the actually visual reference one is supposed to be looking for in the “45 degree rule”)"

And then get jumped on “Here's an even better idea. Know what the uppers are doing each day, time your exit, then stick your head out the door and look DOWN until you're ready to go.”

Forget the fact that I specifically referenced that looking at the ground (which is down by the way in case anyone forgot) is part of the process. It’s then followed up with the presumption that I wouldn’t be looking for other issues such as planes, which is just stupid; OF COURSE one should be looking for those other things. It’s so obvious I would hope it wouldn’t need to be stated. Please excuseeeeuse me (in my best Steve Martin impersonation) for using the generic reference although I already explained that is not the actual intent, "looking at the group that previously left" in future sentences.

I then state, “There is valid information to be gained from sticking one’s head out the door and LOOKING at the group that left previously.” Forget that I already stated that one is really looking for separation over the ground (which means looking down at the distance the plane is traveling over the ground; this is of course ground speed which is a combination of the planes airspeed and the upper level winds). Gee that’s what “timed separation” is trying to do too.

The response I get is,”Well, yes, you can see whose jumpsuit matches whose rig. But while that is perfectly valid information, it doesn't help you know how long to wait.”

So after the silly parsing of words, misconstrued, assaults and other non-sense that goes on anytime someone talks about separation on the site let me put it in simple words for everyone.

I agree timed separation is good; in case anyone missed it in my post I use it. I also believe that looking out the door is good; and believe (other than the usual things one should be looking for such as incoming planes, clouds etc.) that one can get a measure of separation by understanding how fast the plane is traveling over the ground, i.e., making an “eyeball” determination of separation over the ground between groups.

Wow, I think I’ll go protest for Media rights in Venezuela next, the level of discourse is more tame there.

"We've been looking for the enemy for some time now. We've finally found him. We're surrounded. That simplifies things." CP

[billvon 2,380]

>I agree timed separation is good; in case anyone missed it in my post I use it.
>I also believe that looking out the door is good; and believe (other than the
>usual things one should be looking for such as incoming planes, clouds etc.) that
>one can get a measure of separation by understanding how fast the plane is
>traveling over the ground, i.e., making an “eyeball” determination of separation
>over the ground between groups.

Cool, we agree. However, that isn't what you said before. Looking at the group that just left doesn't tell you anything, which is what the 45 degree rule claims.

[MisterCrash 0]

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One day at Otay I outfitted an Otter with cameras and had them run upwind and downwind jump runs. If there's a difference, surely it would be very clear in those pictures. Once again, no difference.

Can you post those pictures or video of those exits? Might be a great help to idiot people like me... Cause I see what the exit separation similator does and I totally believe you can calculate time for adequate seperation. But I still believe exits up and downwind will have a noticable visual difference to them.

Call me hardheaded, I know.
But as long as I don't see god I'm no believer XD.

All speeding past collide and crashing, I'm in paradise.

[strop45 0]

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If your DZSO or CSO requests that you use this rule, I suggest you do so. although 45 degrees might never happen

For the record, neither the DZSO or the CSO or any of the staff at the DZ in question have ever suggested the use of such a rule, they use timed separation based on the difference in wind speeds at exit to opening altitude.

And in any event, how/why do you suggest anyone uses a rule that doesn't work even if a responsible person such as the DZSO required it? If the DZSO required every second person to land downwind because "its safer if skydivers can see each other" would you do it?"

The difference between stupidity and genius is that genius has its limits." -- Albert Einstein