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The 45 Degree Rule… IS DEAD.

 

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BrianSGermain  (D 11154)

Mar 27, 2012, 11:52 PM
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The 45 Degree Rule… IS DEAD. Can't Post

The 45 Degree Rule… IS DEAD.

I got my ass handed to me this week, and I am big enough to admit it. I have been around for a few years, and so it turns out, some of my old assumptions are outdated. One of them came to light a few days ago when I posted a short article in one of the forums on exit order, as a response to a specific request by a jumper. I am always happy to share what I know, but in this case, I illuminated something that I didn’t know I didn’t know.

For years and years, many of us old-timers have taught that keeping your eyes open on jump-run is the best way to ensure exit separation from previous groups. Obviously we must wait significantly longer when the ground speed of the airplane is slow due to high uppers, but many of us have continued to teach the value of watching the previous group drift behind the aircraft. The widely accepted rule became, wait until they are at least a 45 degree angle behind the aircraft, relative to the horizon. This, it was believed, would ensure that they would not be under you when you exited. Apparently, this is not even remotely the case.

It is funny when we repeat the dominant paradigm enough without examining the validity, we can brainwash ourselves into believing it is the truth, and inadvertently be preaching untruth. When we consider the effects of aircraft ground speed on horizontal displacement, the angle relative the aircraft is not the issue. The core of the issue is about how far the airplane has actually moved across the ground. There are several people who have spent far more time on this issue than I have, and I am quite certain that they will chime in here and add further value to this discussion, and I look forward to reading all of it. The point I want to make with this post is that we all must remain open to new ideas, and continually look for more answers. There is a great deal to know about this sport, and the body of information is growing by the day.

So, if you catch one of us old fogies talking about watching the previous group drift to at least 45 degrees, please direct them to this thread and others like it. I will not pretend to understand the whole story here, but I want to make it clear that the bottom line is: time is what matters. Your eyes can fool you into thinking that it is safe to exit because the previous group is no longer under the plane, when in fact you may still get to see them again. Counting is still the best tool, and if the folks behind you start yelling and freaking out on you, turn to them and smile and tell them that everything is going to be OK, and continue to count. Peer pressure is rarely the best means to safety.

Yup, I got reamed on dropzone.com. It happens. Learning requires being wrong and then finding out what is right. I am thankful to all of the kind folks who helped clarify this issue for me, and hopefully in my wrongness, I will help others to see the truth on this issue. Together we learn, together we survive.

Love y'all
Bri


shropshire  (C License)

Mar 28, 2012, 3:21 AM
Post #2 of 70 (3217 views)
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Re: [BrianSGermain] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

Cool


pchapman  (D 1014)

Mar 28, 2012, 5:50 AM
Post #3 of 70 (3129 views)
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Re: [BrianSGermain] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

Hallelujah!
We have a new convert -- who is a teacher to a lot of other skydivers and can help others understand too.
(If he doesn't keep on just going on and on about canopies. Smile)


Divalent  (C 40494)

Mar 28, 2012, 5:55 AM
Post #4 of 70 (3121 views)
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Re: [BrianSGermain] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
... Counting is still the best tool, and if the folks behind you start yelling and freaking out on you, turn to them and smile and tell them that everything is going to be OK,

If I understand the take home message from the long standing thread on this issue, Ground distance traveled is the best tool. Counting is the NEXT best tool IF (and ONLY IF!!!) you have determined the proper count time based on the ground speed. And usually ground speed can only be estimated by wind and plane speed. Ideally planes would have a gps that gave actual ground speed at jump run time with that information used to determine the best count.(but apparently it's not common for plane gps information to be communicated to jumpers for that purpose).


(This post was edited by Divalent on Mar 28, 2012, 5:56 AM)


5.samadhi

Mar 28, 2012, 6:05 AM
Post #5 of 70 (3104 views)
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Re: [BrianSGermain] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

I really look forward to taking a canopy course with you some day...your attitude is exactly what I would want in a teacher :)


popsjumper  (D 999999999)

Mar 28, 2012, 6:11 AM
Post #6 of 70 (3098 views)
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Re: [BrianSGermain] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

Once again, you prove yourself to be Da' Man!
Smile


popsjumper  (D 999999999)

Mar 28, 2012, 6:26 AM
Post #7 of 70 (3079 views)
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Re: [Divalent] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
If I understand the take home message from the long standing thread on this issue, Ground distance traveled is the best tool. Counting is the NEXT best tool IF (and ONLY IF!!!) you have determined the proper count time based on the ground speed. And usually ground speed can only be estimated by wind and plane speed.
Yes, you have it.

In reply to:
Ideally planes would have a gps that gave actual ground speed at jump run time with that information used to determine the best count.
...but then you lost it with the "ideally" word.

As you probably already know, spotting is a lost art these days. Few people really know how to spot.
We used to use WDIs which was good for canopy descent under rounds but it didn't take into consideration the freefall drift we had for higher altitude jumps.

The advent and use of GPS for skydiving is the single-most contributor to the loss of real spotting skills in the sport.

Unfortunately, many instructors teach "spotting" simply as looking out the door, checking for clouds, air traffic and the LZ. That's not spotting.

Spotting involves determining exit and opening points and directing the pilot to be at the proper place at the proper time and altitude.

While GPS is good for telling were you are, when it works properly and when the pilot interprets properly, it tells you nothing about proper exit and opening points.

We as skydivers are the ones who determine that. Only knowledge, practice and skill can set those spots properly with some degree of reliability.

It would behoove us all, particularly you young jumpers, to learn to spot properly. And it only comes from putting a pencil in your hand and doing the math. One of these days, YOU are going to be the one to be telling people when and where to exit. I hope you put them on the LZ.

If you are not completely sure how to determine opening and exit points, come talk to me. I will be thrilled to show you.


stayhigh  (F 111)

Mar 28, 2012, 6:46 AM
Post #8 of 70 (3053 views)
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Re: [BrianSGermain] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

I teach em about 45 degree only and only when no other sources are available.

If pilot tells me "I have no clue", and there was nothing down by the manifest, and if no one on the load knows, 45 degree is better than nothing.


skydiverek  (C 952)

Mar 28, 2012, 7:00 AM
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Re: [stayhigh] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
I teach em about 45 degree only and only when no other sources are available.

If pilot tells me "I have no clue", and there was nothing down by the manifest, and if no one on the load knows, 45 degree is better than nothing.

45 degree rule is a source with ZERO VALUE. Having NO DATA whatsoever, I would watch the ground covered distance with my eyes, or, if ground view was partially obstructed by clouds, leave 15 seconds between groups just to be safe.


kallend  (D 23151)

Mar 28, 2012, 7:17 AM
Post #10 of 70 (3012 views)
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Re: [stayhigh] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
I teach em about 45 degree only and only when no other sources are available.

If pilot tells me "I have no clue", and there was nothing down by the manifest, and if no one on the load knows, 45 degree is better than nothing.

Well, DON'T.

It's NOT better than nothing. It has no validity whatsoever.

That has been proven both theoretically and by empirical observation.


kallend  (D 23151)

Mar 28, 2012, 7:18 AM
Post #11 of 70 (3008 views)
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Re: [BrianSGermain] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

SmileSmileSmileSmileSmileSmileSmileSmileSmile


airtwardo  (D License)

Mar 28, 2012, 7:34 AM
Post #12 of 70 (2987 views)
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Re: [skydiverek] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
In reply to:
I teach em about 45 degree only and only when no other sources are available.

If pilot tells me "I have no clue", and there was nothing down by the manifest, and if no one on the load knows, 45 degree is better than nothing.

45 degree rule is a source with ZERO VALUE. Having NO DATA whatsoever, I would watch the ground covered distance with my eyes, or, if ground view was partially obstructed by clouds, leave 15 seconds between groups just to be safe.

Yeah I'm just an old fart...but I believe if you can't spot efficiently by your C license you'd better take some lessons. If I were King it would be part of the D license requirements.

Stay aware during the climb, look outside of the aircraft. You can tell upper winds by watching the cloud shadows on a sunny day, by seeing the drift of the aircraft as it makes turns during the accent.

Watch from the ground where other loads are exiting and opening, evaluating the ease or difficulty they have getting back.

Create a 3D picture in your mind of a cube of space around the LZ and use your observations to factor an equation that works...Winds can dogleg or even reverse direction in the cube, understand how that effects your exit and opening points and adjust.

As far as the 45 degree rule, IIRC it's an olden days thing that was used when we were doing belly RW with balloon suits and the like, it was 'good enough' until folks started going head down etc.

I always went with the 10 count...and count -s l o w- like you're waiting for dinner with the in-laws. . . THEN start your climb-out for your exit. Look down before you start, if you've gone way past the 'spot' either plan to pull higher and let those behind ya know or go around.


airtwardo  (D License)

Mar 28, 2012, 7:37 AM
Post #13 of 70 (2977 views)
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Re: [kallend] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
SmileSmileSmileSmileSmileSmileSmileSmileSmile

I never really used the 45 degree rule but heard it often and understood the theory...that is until I looked at the little illustration you made a few years back showing how not only was it not valid...it was dangerous.

That tool taught this old dog a new thing or two. Cool


Arvoitus  (D 3917)

Mar 28, 2012, 7:45 AM
Post #14 of 70 (2967 views)
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Re: [airtwardo] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
In reply to:
In reply to:
I teach em about 45 degree only and only when no other sources are available.

If pilot tells me "I have no clue", and there was nothing down by the manifest, and if no one on the load knows, 45 degree is better than nothing.

45 degree rule is a source with ZERO VALUE. Having NO DATA whatsoever, I would watch the ground covered distance with my eyes, or, if ground view was partially obstructed by clouds, leave 15 seconds between groups just to be safe.

Yeah I'm just an old fart...but I believe if you can't spot efficiently by your C license you'd better take some lessons. If I were King it would be part of the D license requirements.

In Finland you can't get your A-license without being able to spot and/or use a WDI to determine the exit point.


DBCOOPER  (D 24112)

Mar 28, 2012, 7:50 AM
Post #15 of 70 (2962 views)
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Re: [airtwardo] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

I use the 45 degree rule all the time. It works perfectly. If its 45 degrees or colder I don't jump.


jaitken  (B License)

Mar 28, 2012, 8:05 AM
Post #16 of 70 (2938 views)
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Re: [skydiverek] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
45 degree rule is a source with ZERO VALUE.

The quote that has always stuck with me is: "So using the '45 degree rule' in combination with time is as sensible as using the number of fleas on my dog in combination with time to ensure separation."

Thank you Dr. Kallend. Smile


kallend  (D 23151)

Mar 28, 2012, 8:48 AM
Post #17 of 70 (2899 views)
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Re: [jaitken] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
In reply to:
45 degree rule is a source with ZERO VALUE.

The quote that has always stuck with me is: "So using the '45 degree rule' in combination with time is as sensible as using the number of fleas on my dog in combination with time to ensure separation."

Thank you Dr. Kallend. Smile

You're very welcome. Smile


scottd818  (C 41314)

Mar 28, 2012, 8:56 AM
Post #18 of 70 (2889 views)
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Re: [Arvoitus] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
In reply to:
In reply to:
In reply to:
I teach em about 45 degree only and only when no other sources are available.

If pilot tells me "I have no clue", and there was nothing down by the manifest, and if no one on the load knows, 45 degree is better than nothing.

45 degree rule is a source with ZERO VALUE. Having NO DATA whatsoever, I would watch the ground covered distance with my eyes, or, if ground view was partially obstructed by clouds, leave 15 seconds between groups just to be safe.

Yeah I'm just an old fart...but I believe if you can't spot efficiently by your C license you'd better take some lessons. If I were King it would be part of the D license requirements.

In Finland you can't get your A-license without being able to spot and/or use a WDI to determine the exit point.

Its on the A license proficency card from the USPA as well.


kallend  (D 23151)

Mar 28, 2012, 8:56 AM
Post #19 of 70 (2889 views)
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Re: [airtwardo] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:

Yeah I'm just an old fart...but I believe if you can't spot efficiently by your C license you'd better take some lessons. If I were King it would be part of the D license requirements.

How would you evaluate it?


jhh166  (B License)

Mar 28, 2012, 9:01 AM
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Re: [BrianSGermain] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

Nothing wrong with learning something new. Nobody knows everything (well except for a few on DZ who eventually learned the hard way). You posses a good leadership trait - admitting you were wrong allows you to move along and master more knowledge.

I owe you a few thanks for teaching me some skills that I have already used in potentially dangerous situations!


Divalent  (C 40494)

Mar 28, 2012, 9:18 AM
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Re: [popsjumper] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
... you lost it with the "ideally" word.
As you probably already know, spotting is a lost art these days. Few people really know how to spot. ...

Spotting for exit separation, as far as I can see, was never an art to have been lost. (Or else, why did they have the 45 degree rule?) [Spotting for exit point is a different matter.]

In the age of GPS, for the life of me, can't see why is isn't used for separation (backed by visual confirmation). You look through the "45 degree rule" thread (the one you resurrected) and the various alternatives are complicated, and require the jumpers to know wind speed, plane air speed, directions, etc, then either do the math (pretty complicated) or do some math and then consult a spreadsheet. And at best it is an approximation, since most winds aloft values are estimates generated many hours in advance, and might not be relevant to conditions right now, as you are poised in the door frame about to jump. That fact that the suggestions in that thread have little value is made clear by the fact that it’s a 7 year old thread that gets resurrected about every 6 months, and none of the suggested alternative has become the universal standard method.

A working GPS will tell you correct information at that instant. Many planes have them. Why not have the pilot announce the value as he begins jump run, and then a quick consult with a simple table will give you the right number? It's the simpliest fucking thing ever!

Pilot: "ground speed is 70 knots"
One jumper consults table posted in the plane: 70 knots = X second for 1,000ft of exit separation
Jumper: "use a count of X seconds between groups!"

No math, no having to remember winds aloft speed and direction (old data anyway) and then having to vector that with jump run air speed and direction (applying pythagorean theorem and doing square roots to get hypotenuse). Ground speed, ground speed, ground speed. There is an app for that!


(This post was edited by Divalent on Mar 28, 2012, 9:20 AM)


kallend  (D 23151)

Mar 28, 2012, 9:28 AM
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Re: [Divalent] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
In reply to:
... you lost it with the "ideally" word.
As you probably already know, spotting is a lost art these days. Few people really know how to spot. ...

Spotting for exit separation, as far as I can see, was never an art to have been lost. (Or else, why did they have the 45 degree rule?) [Spotting for exit point is a different matter.]

In the age of GPS, for the life of me, can't see why is isn't used for separation (backed by visual confirmation). You look through the "45 degree rule" thread (the one you resurrected) and the various alternatives are complicated, and require the jumpers to know wind speed, plane air speed, directions, etc, then either do the math (pretty complicated) or do some math and then consult a spreadsheet. And at best it is an approximation, since most winds aloft values are estimates generated many hours in advance, and might not be relevant to conditions right now, as you are poised in the door frame about to jump. That fact that the suggestions in that thread have little value is made clear by the fact that it’s a 7 year old thread that gets resurrected about every 6 months, and none of the suggested alternative has become the universal standard method.

A working GPS will tell you correct information at that instant. Many planes have them. Why not have the pilot announce the value as he begins jump run, and then a quick consult with a simple table will give you the right number? It's the simpliest fucking thing ever!

Pilot: "ground speed is 70 knots"
One jumper consults table posted in the plane: 70 knots = X second for 1,000ft of exit separation
Jumper: "use a count of X seconds between groups!"

No math, no having to remember winds aloft speed and direction (old data anyway) and then having to vector that with jump run air speed and direction (applying pythagorean theorem and doing square roots to get hypotenuse). Ground speed, ground speed, ground speed. There is an app for that!

No need for any theorems. You don't make your point valid by exaggerating.

Trouble with the "simple table" is that two 10-ways need more separation than 2 solos.

Knowledge IS power.


3mpire  (C 39657)

Mar 28, 2012, 9:33 AM
Post #23 of 70 (2834 views)
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Re: [kallend] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

Quote:
How would you evaluate it?

Make someone spot for the whole load, and require that everyone open up wind and in a position where people are able to promote a smooth pattern for landing.

If they are too early then people will be opening downwind. If they are too late the last people out may need a go-around.

Make them look at the winds aloft and estimate separation times and have them communicate that to the load before leaving the ground.

Have them tell the pilot what jump run they want and have the pilot fly that jump run.

Have the pilot give them a MEGA early green light so they have to open the door and actually look, identify the spot, and then climb out.

If they can do that say 5 times over at least two different days then you could argue they have an idea of how to spot.

I love spotting. It's like a puzzle where you take in all the data inputs you have and then seeing it all come together is really fun. That's easier to do at a smaller DZ though.

When it's a 182 you can ask for any jump run you want and you have more control over it.

If you've got a tandem filled otter then you pretty much just get out when you are told because they don't have time to waste because they're trying to keep things moving.


kallend  (D 23151)

Mar 28, 2012, 9:35 AM
Post #24 of 70 (2828 views)
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Re: [3mpire] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
Quote:
How would you evaluate it?

Make someone spot for the whole load, and require that everyone open up wind and in a position where people are able to promote a smooth pattern for landing.

If they are too early then people will be opening downwind. If they are too late the last people out may need a go-around.

Make them look at the winds aloft and estimate separation times and have them communicate that to the load before leaving the ground.

Have them tell the pilot what jump run they want and have the pilot fly that jump run.

Have the pilot give them a MEGA early green light so they have to open the door and actually look, identify the spot, and then climb out.

If they can do that say 5 times over at least two different days then you could argue they have an idea of how to spot.

I see, 5 loads of jumpers put at risk so you can evaluate someone's spotting ability. Got it.


(This post was edited by kallend on Mar 28, 2012, 9:35 AM)


Southern_Man  (C License)

Mar 28, 2012, 9:36 AM
Post #25 of 70 (2823 views)
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Re: [Divalent] The 45 Degree Rule… IS DEAD. [In reply to] Can't Post

In reply to:
Pilot: "ground speed is 70 knots"
One jumper consults table posted in the plane: 70 knots = X second for 1,000ft of exit separation
Jumper: "use a count of X seconds between groups!"

No math, no having to remember winds aloft speed and direction (old data anyway) and then having to vector that with jump run air speed and direction (applying pythagorean theorem and doing square roots to get hypotenuse). Ground speed, ground speed, ground speed. There is an app for that!

This is what my drop zone does. It works. Yes, to answer Kallend's next point, we allow a few extra seconds for larger groups (it is not a problem as a larger group or two means you have less groups overall, so jump run doesn't get strung out as far).

Not sure why every drop zone doesn't do this? At least the ones w/ GPS or otherwise able to give an accurate ground speed.


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