The 45 Degree Rule… IS DEAD.

[kallend 2,147]

Quote

Quote

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).

.

Knowledge IS power

...

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

[billvon 3,114]

>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.

While I agree, the only reason it is better than nothing is that it delays people a little bit, and thus adds to exit separation. (In other words, it's better than just climbing out as fast as you can, but that delay is its only value.)

[peek 21]

Divalent posted: "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?"

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

You both make very good points. What I would like to see is more communication between pilots and jumpers. This covers Divalent's point.

Those of you who have jumped from Mike Mullins' King Air may have noticed that he asks people the details of the groups getting out so he can adjust the spot. This pretty much covers Kallend's point.

I wonder why there isn't more communication. Perhaps we should ask for it.

[3mpire 0]

Quote

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

It's an A license requirement that you essentially do all of that anyway. You are supposed to brief the pilot, you are supposed to give corrections and you are supposed to spot.

Nobody says that the rest of the load has to get out. Each jumper is responsible for their own spot. And everyone should know how to spot, right?

So if the person up front has a bad spot the following jumpers should see that and take responsibility for themselves and make corrections with the pilot or ask for a go around.

Nothing about that should be out of the ordinary. That should be happening on *every load*. If simply evaluating someone on something that should be absolutely routine puts jumpers at risk then we have a pretty big problem, don't we?

[popsjumper 2]

Quote

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.]

OK. We differ. In my book, determining exit separation is part of spotting. YMMV

Quote

In the age of GPS, for the life of me, can't see why is isn't used for separation....

Because it has been, and pilots have been, wrong and generates device dependency. And not every plane, pilot or DZ uses GPS.

Quote

You look through the "45 degree rule" thread (the one you resurrected) and the various alternatives are complicated,

We differ. The process is not complicated and the arithmetic is simple.

Quote

...and require the jumpers to know wind speed, plane air speed, directions, etc,

Things we all should know before we board. Is there a problem with that? My memory tells me that I taught you to know all that. Are you telling me you have trashed that advice?

Quote

then either do the math (pretty complicated)

Add, subtract, multiply and divide...again, not complicated at all.

Quote

most winds aloft values are estimates

True. There are no absolutes in skydiving.

Quote

none of the suggested alternative has become the universal standard method.

Read your SIM for the U.S. standard.

Quote

A working GPS will tell you correct information at that instant.

Better so than the winds aloft forecasts and reports, true.

IF you can get the most accurate information while on the plane and IF you can do the math while on the plane, then yes, using more accurate info will help.

Quote

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 done that was at several DZs with a list pasted on the bulkead. *LouDiamond posted a good one.

Now, you're used to depending on that GPS, the pilot having the info and the chart on the wall. What are you gonna do when you go to a place that has none of that?

Learning to spot and taking responsibility for your own safety and the safety of others is the simplest fucking thing in the world to do.

Quote

There is an app for that!

Let me know when you are "spotting" and using your app but please do so before I board.


I'll suggest again to you Peter that you learn what to do and how to do it for your own safety and the safety of others.

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

[Divalent 155]

Quote

No need for any theorems.

You do if jump run is not heading into the wind. At the Farm it almost always is due E or due W, regardless of wind direction, since the LZ is very long E/W, and not so much N/S (so even if winds are from the north, unless they are really honking, its an E/W jump run).

A GPS will effectively do the math for you, and it will be using actual conditions at that moment, not projections that are old.

Quote

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

Of course, but unlike using a valid method for generating an appropriate exit separation time, I think most jumpers are aware of this, and will adjust accordingly.

[popsjumper 2]

Quote

How would you evaluate it?

Quote

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.

I would like to think that everyone could/would do as you indicated. I do similar. Personally, I totally agree with making them actually do it, just as you do, to determine success but with one exception.

I let them do the math to determine earliest exit point, middle (perfect) exit point and latest exit point. Then take them up on the plane. I tell the pilot to fly off-line to check to see if the student does proper corrections. Then they tell me when they get to the first exit point and I verify or deny. I tell them on the ground, "If I land off, you will have to repeat the class and try again."


I, like you, prefer to do this on a 182 or such so that there would be fewer jumpers involved in the process and I would always take back control if the student was getting it so wrong as to endanger anyone with off landings. If their spotting is "good enough" to minimize the danger to other jumpers, I'll go ahead and exit.

On a larger plane involving more jumpers, I will let them do the same but I'll take control just before exit and take the responsibility myself instead of putting on the student.

Once he can prove some consistency, he on his own.

Good stuff, 3mpire.

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

[kallend 2,147]

Quote

Quote

No need for any theorems.

You do if jump run is not heading into the wind. At the Farm it almost always is due E or due W, regardless of wind direction, since the LZ is very long E/W, and not so much N/S (so even if winds are from the north, unless they are really honking, its an E/W jump run).

A GPS will effectively do the math for you, and it will be using actual conditions at that moment, not projections that are old.

Quote

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

Of course, but unlike using a valid method for generating an appropriate exit separation time, I think most jumpers are aware of this, and will adjust accordingly.

Well, a previous poster cast doubt on jumpers' abilities to do any calculations. Now you expect them to make adjustments from your "simple" table. make up your mind what it is that you are trying to say.

Knowledge is power. GPS is a crutch. A very clever crutch, but a crutch nonetheless.

...

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

[popsjumper 2]

Quote

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.

I'll repeat for you what Divalent obviously missed:
(and for God's sake don't take it as harsh.)

Now, you're used to depending on that GPS, the pilot having the info and the chart on the wall. What are you gonna do when you go to a place that has none of that?

I know the answer of what I would do. I'm interested on what others would do when they don't have crutches of GPS and charts on the bulkhead to depend on.

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

[kallend 2,147]

Quote

Quote

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

It's an A license requirement that you essentially do all of that anyway. You are supposed to brief the pilot, you are supposed to give corrections and you are supposed to spot.

Nobody says that the rest of the load has to get out. Each jumper is responsible for their own spot. And everyone should know how to spot, right?

But you wrote previously

Quote

"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. "

You are being inconsistent.

Quote

So if the person up front has a bad spot the following jumpers should see that and take responsibility for themselves and make corrections with the pilot or ask for a go around.

Nothing about that should be out of the ordinary. That should be happening on *every load*. If simply evaluating someone on something that should be absolutely routine puts jumpers at risk then we have a pretty big problem, don't we?

Everyone spotting for themselves is not very convenient on, say, a 20 way.

...

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

[rehmwa 2]

Quote

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!"

This is GREAT. With common sense adjustments (Kallend's note about following a big way vs a bunch of solos) apply and most people aren't idiots - it works just fine.

1 - I look out the window (we tend to take jumprun into the wind - typically uppers are faster than ground winds - typically uppers close enough to the same direction as ground winds):
a - are we crawling along (relative to the ground)? I take a long delay.
b - are we screaming along (relative to the ground)? I take a short delay

2 - Our pilot will actually call out ground speed when he turns on jump run. It'll confirm my visual observation. But if I don't hear him, it's not a big deal.

3 - Door opens - check for traffic. Again, a glance tells us our penetration....

4 - Stage the exits accordingly

5 (seriously, it's assessed during the day anyway, and this rarely results in any difference than what the DZ designates based on 'doing the math' - but the personal check is just the right thing to do anyway)


if the winds (uppers vs grounds) directions and speeds are NOT 'typical' - then we use our brains.


it's not rocket science - or is it?

...
Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[rehmwa 2]

Doc -about throw - I once noted to another jumper that our approach to a big way base was really steep. She insisted that it was steep because the uppers were really high........

I pointed out that the airspeed of the airplane doesn't care about wind aloft in this case. She got angry and insisted on it. (I guessed that the base funneled on exit - right or wrong - it turns out, it did funnel)

This is why old 'rules' stick around. For that matter, her conclusions were even backwards when based on her personal and faulty theory.......



Canopy flight guys can best appreciate the frustration by noting this attitude is exactly analogous as when someone points out that front risering when landing into the wind will cause the canopy to roll under - because, obviously, the head wind pushed the nose under - but front risering on a downwinder is fine.... -

or, another good one - a tail wind pushes the canopy,,,,,

teaching relative reference frames for flight is VERY difficult when the audience is normally land based.

...
Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[kallend 2,147]

Quote

it's not rocket science - or is it?

Apparently it is, or the 2004 thread wouldn't need resurrecting every 2 years. If it were easy a dead squirrel could do it.

...

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

[kallend 2,147]

Quote

Doc -about throw - I once noted to another jumper that our approach to a big way base was really steep. She insisted that it was steep because the uppers were really high........

I pointed out that the airspeed of the airplane doesn't care about wind aloft in this case. She got angry and insisted on it. (I guessed that the base funneled on exit - right or wrong - it turns out, it did funnel)

This is why old 'rules' stick around. For that matter, her conclusions were even backwards when based on her personal and faulty theory.......



Canopy flight guys can best appreciate the frustration by noting this attitude is exactly analogous as when someone points out that front risering when landing into the wind will cause the canopy to roll under - because, obviously, the head wind pushed the nose under - but front risering on a downwinder is fine.... -

or, another good one - a tail wind pushes the canopy,,,,,

teaching relative reference frames for flight is VERY difficult when the audience is normally land based.

Perhaps a dead Einstein could be brought along.

...

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

[popsjumper 2]

Quote

Quote

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!"

This is GREAT. With common sense adjustments (Kallend's note about following a big way vs a bunch of solos) apply and most people aren't idiots - it works just fine.

1 - I look out the window (we tend to take jumprun into the wind - typically uppers are faster than ground winds - typically uppers close enough to the same direction as ground winds):
a - are we crawling along (relative to the ground)? I take a long delay.
b - are we screaming along (relative to the ground)? I take a short delay

2 - Our pilot will actually call out ground speed when he turns on jump run. It'll confirm my visual observation. But if I don't hear him, it's not a big deal.

3 - Door opens - check for traffic. Again, a glance tells us our penetration....

4 - Stage the exits accordingly

5 (seriously, it's assessed during the day anyway, and this rarely results in any difference than what the DZ designates based on 'doing the math' - but the personal check is just the right thing to do anyway)


if the winds (uppers vs grounds) directions and speeds are NOT 'typical' - then we use our brains.


it's not rocket science - or is it?

Couple of questions:
1. How do you determine when the winds are not "typical at the middle latitudes?

2. How exactly do you determine how long of a delay to take?

3. What does "crawling" and "screaming" mean and what's the dividing line between the two?

4. What does "stage exits accordingly" mean?

And no, the math is not rocket science. It beats the hell out of guessing.

And yes, we can adjust as the day progresses from load to load when the winds are consistent. We re-calculate when the winds demonstrate radical changes. Simple as that.

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

[popsjumper 2]

Quote

or, another good one - a tail wind pushes the canopy,,,,,.

Oh hell yeah! This is one of my favorites!
You'd be surprised how common this misconception is.


or really,

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

[Southern_Man 0]

Quote

I'll repeat for you what Divalent obviously missed:
(and for God's sake don't take it as harsh.)

Now, you're used to depending on that GPS, the pilot having the info and the chart on the wall. What are you gonna do when you go to a place that has none of that?

I know the answer of what I would do. I'm interested on what others would do when they don't have crutches of GPS and charts on the bulkhead to depend on.

Well, if the uppers are posted (I have not been to a drop zone where I could not get that information) then I know what the timing should be based on the forecast. I am also more than capable of sticking my head out the door and verifying that the plane has traveled at least .2 miles over the ground since the last group exited.

"What if there were no hypothetical questions?"

[popsjumper 2]

Quote

Perhaps a dead Einstein could be brought along.

Now wait just a minute here! It's bad enough that the bean-eaters are on the plane and now you want to add a dead Einstein?

Ewwwwww.

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

[rehmwa 2]

Quote

Couple of questions:
1. How do you determine - winds aloft chart posted in the hanger

2. How exactly rough calcs to achieve approx 1000 ft of separation at opening

3. What does crawling - are we pretty much stationary over the ground? expect this when winds are 85/90/100 mph at altitude - see the winds aloft chart for expectations. Screaming - very definite progress across the ground - winds aloft are low

4. What does - if I'm following a big way, I add a bit, if I'm out of order like belly after FF I add a lot - if you ask me to define "a bit" or "a lot" I'll mail a bag of dead cat to you

I get the feeling that in the case of exit separation, you are arguing the differences within the normal variation of just how fast people count and climb out. rather than just process. (or,..... this is a training opportunity to clarify to the quiet audience.....)

We can discuss it at a boogie someday,


Point is, we did the math correctly, and DZ says "take 8 seconds between groups". If I look down and the plane is at a standstill - I will adjust and take a much longer delay - and I will let the other jumpers know that winds have pick up significantly at altitude. things change - it doesn't hurt to look and think

...
Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[popsjumper 2]

Quote

Well, if the uppers are posted (I have not been to a drop zone where I could not get that information) then I know what the timing should be based on the forecast. I am also more than capable of sticking my head out the door and verifying that the plane has traveled at least .2 miles over the ground since the last group exited.

There you go! Therein lies the answer. Stick your head out and watch X number of feet go by. It works when winds are "typical".

I see you are using the winds aloft forecast and you're right...that's what we have to go on to start with. Wind direction and speed in the middle layers are also taken into consideration.

You with your experience are doing some of those calculations in your head and that comes with experience. It comes with knowing what you are doing in the first place.

My personal opinion is that it's more dependable to show the math in different conditions than it is to simply explain it to the young jumpers.

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

[kallend 2,147]

Quote

Quote

Couple of questions:
1. How do you determine - winds aloft chart posted in the hanger

2. How exactly rough calcs to achieve approx 1000 ft of separation at opening

3. What does crawling - are we pretty much stationary over the ground? expect this when winds are 85/90/100 mph at altitude - see the winds aloft chart for expectations. Screaming - very definite progress across the ground - winds aloft are low

4. What does - if I'm following a big way, I add a bit, if I'm out of order like belly after FF I add a lot - if you ask me to define "a bit" or "a lot" I'll mail a bag of dead cat to you

I get the feeling that in the case of exit separation, you are arguing the differences within the normal variation of just how fast people count and climb out. rather than just process.

We can discuss it at a boogie someday,


Point is, we did the math correctly, and DZ says "take 8 seconds between groups". If I look down and the plane is at a standstill - I will adjust and take a much longer delay - and I will let the other jumpers know that winds have pick up significantly at altitude. things change - it doesn't hurt to look and think

See - it IS rocket science.

...

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

[rehmwa 2]

Quote

See - it IS rocket science.

or taxidermy

...
Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[popsjumper 2]

Quote

I get the feeling that in the case of exit separation, you are arguing the differences within the normal variation of just how fast people count and climb out.

Well, no I haven't alluded to that intentionally but it IS a very good point.

Quote

this is a training opportunity to clarify to the quiet audience.....)

Well, yes, I DO hope that at least someone takes away something positive from all this, and other threads dealing with spotting. I resurrected one thread just for that purpose...education for the youngsters who may have been led astray with other methods.

Quote

We can discuss it at a boogie someday,

Yes, hopefully so.

Quote

Point is, we did the math correctly, and DZ says "take 8 seconds between groups".

No dead cats please!


Central to my entire point, and I thank you:
"Point is, we did the math correctly,"
Good stuff. Everything else is gravy....and the good gravy comes with the experience.

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

[rehmwa 2]

Quote

Central to my entire point, and I thank you:
"Point is, we did the math correctly,"
Good stuff. Everything else is gravy....and the good gravy comes with the experience.

See, I don't think it's gravy. the math is the gravy. The meat is that you need to develop the ability to confirm, real time (before climbout), based on direct observation, that the calc remains true. (spotting skills come in handy here - use a hard edge on the plane - window frame, edge of door etc to reference the progress across the ground)


as for error bars.....if we decide 10 seconds, and I see people getting out between 8 and 18 seconds, I'm pretty much happy they are doing their best to comply - most people take a lot longer than they think


blues - this is always a worthwhile discussion. And Brian's attitude here is a great role model for us. We always learn.

...
Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[Divalent 155]

Quote

..Well, a previous poster cast doubt on jumpers' abilities to do any calculations. Now you expect them to make adjustments from your "simple" table. make up your mind what it is that you are trying to say.

Okay, now you are just being silly. A very high percentage of all jumpers on a typical load could not tell you what the upper wind velocity was, let alone the direction. And of the few that did know, some of them could not tell you the plane's air speed. And of the remainder that know both, I'd be willing to bet a lot that, in the last year, of the millions of jumps made in the world, only a tiny tiny fraction of those jumpers actually did the math in their head to derive a time for whatever exit separation distance they wanted.

But I will also bet that almost all of those jumpers, if told that XX seconds is the normal group separation for the conditions at the moment will be smart enough to add more time to account for a big way in front of them. And most big ways I've been behind, at least one of the participants was reminding the groups behind them to give them more time. This is not a problem: I've seen that typical jumpers do get this, and they do attempt to adjust accordingly.

Any method is useless if it is impractical and/or complicated and/or goes against the known abilities and actual behavior of the bulk of the skydivers on the load. It's not so much the complexity of the math, it's the number of variable in the equation. There is absolutely nothing wrong with teaching everyone the logic and the method (in fact, better to state that "it is absolutely the right thing to do"), but the reality is that it isn't being put into practice. The original thread (that you started) is 7 years old, and don't you think it's telling that the author of the best selling canopy book and teacher of the most famous canopy course is (was) advocating the 45 second rule? (I heard "the 45 second rule" being urged on a load last month.) It seems to me that you have to keep beating down the "45 second rule" like a whack-a-mole because no one is advocating a practical workable substitute.

A working GPS will tell you ground speed regardless of the conditions: air speed, wind speed, whether flying directly into the wind or crabbing, the otter or the king air or the 182, whatever. Yes, instruments can fail. Jumpers should use their eyes to make sure what the GPS accords with reality. But a GPS does do the math for you (with the correct data). It get you the penultimate number you need: ground speed. The ultimate number (exit count) is just one step away, easily obtained from a simple chart, that requires the jumper to know only one variable that is apparent only from the grouping on the plane: exit separation in distance.

Quote

Knowledge is power. GPS is a crutch. A very clever crutch, but a crutch nonetheless.

So are hand held calculators, altimeters, airspeed indicators, speedometers, and fuel tank gauges.