The "45 degree rule" for exit separation DOES NOT WORK

[gowlerk 1,903]

wasatchrider

am I the only one that does not know what the 45 degree rule is?

Go to the beginning of the thread. Read the 3rd post.

Always remember the brave children who died defending your right to bear arms. Freedom is not free.

[yoink 321]

wasatchrider

am I the only one that does not know what the 45 degree rule is?

That's great!

Seriously.

[gowlerk 1,903]

yoink

***am I the only one that does not know what the 45 degree rule is?

That's great!

Seriously.


ouch

Always remember the brave children who died defending your right to bear arms. Freedom is not free.

[yoink 321]

Why ouch?

I'm dead serious.


If people don't know what the 45 degree rule is, that means it may not be propagating as much. That's really good for us.

[JWest 0]

Mark,

Basically just waiting till the previous jumper was horizontally at 45 away from the plane. I don't use it, I count and everyone on the load usually does.

[mark 102]

JWest

Basically just waiting till the previous jumper was horizontally at 45 away from the plane. I don't use it, I count and everyone on the load usually does.

You don't use it because it doesn't work? Or just doesn't work as well as counting?

Also, "usually" means there are cases where at least one person does not use the counting method. What method does that person use?

Mark

[fcajump 153]

mark

***Basically just waiting till the previous jumper was horizontally at 45 away from the plane. I don't use it, I count and everyone on the load usually does.

You don't use it because it doesn't work? Or just doesn't work as well as counting?

Also, "usually" means there are cases where at least one person does not use the counting method. What method does that person use?

Mark

The 45degree method (which I was taught when I started) has been mathematically, computationally and empirically proven not to work.

The person who does not count, is relying upon past experience and luck to given them the separation we need.

The best method we have so far seems to be a GPS derived ground speed on jump run, separation count chart with notations for larger groups/higher breakoff with longer tracks, and a calm/reliable count.

Note: if you are counting and THEN starting your climb-out, u're doin' it wrong. The full separation count should INCLUDE your climb-out and exit count time. If you're the last out, whatever... but in the middle of a large plane this can be an issue.

JW

Always remember that some clouds are harder than others...

[gowlerk 1,903]

yoink

Why ouch?

I'm dead serious.


If people don't know what the 45 degree rule is, that means it may not be propagating as much. That's really good for us.

I agree. But when looking at his profile, he probably knows very well what it is. He is just strongly encouraging everyone to act a though there is no such thing. Which we both agree on. "ouch" was because I didn't pick it up at first.

Always remember the brave children who died defending your right to bear arms. Freedom is not free.

[mark 102]

fcajump

******

You don't use it because it doesn't work? Or just doesn't work as well as counting?

Also, "usually" means there are cases where at least one person does not use the counting method. What method does that person use?

Sorry, I should have been clearer. I wanted to know what JWest thought.

-Mark

[chuckakers 369]

fcajump

******The best method we have so far seems to be a GPS derived ground speed on jump run, separation count chart with notations for larger groups/higher breakoff with longer tracks, and a calm/reliable count.

Even this commonly accepted technique fails to include the most critical data of all - the difference in wind speed and direction between the exit altitude and the planned deployment altitude.

Chuck Akers
D-10855
Houston, TX

[fcajump 153]

chuckakers

*********The best method we have so far seems to be a GPS derived ground speed on jump run, separation count chart with notations for larger groups/higher breakoff with longer tracks, and a calm/reliable count.

Even this commonly accepted technique fails to include the most critical data of all - the difference in wind speed and direction between the exit altitude and the planned deployment altitude.

Agreed... hence the caviot that its "the best method we have so far"...

This is where (in addition to looking/paying attention) the feed-back loop is essential... jumpers both on the ground and in the air should note how well things are working and get the next load to adjust their spot/jump-run/timing/etc... to get the necessary location and separation.

Its bad enough when one load has issues, repeating it on the next (few) is just wrong.

JW

Always remember that some clouds are harder than others...

[billvon 2,380]

>am I the only one that does not know what the 45 degree rule is?

You are fortunate! It's like not knowing what a Nova was.

[billvon 2,380]

>Even this commonly accepted technique fails to include the most critical data of
>all - the difference in wind speed and direction between the exit altitude and
>the planned deployment altitude.

It still works extremely well, because it relies on the assumption that winds at opening altitude are usually a similar direction but lower strength than the winds at altitude - and that is correct 99% of the time.

In the very rare instances that that assumption is not correct (as is the case during some _very_ unusual weather conditions) then you can see less separation than you expect.

[rehmwa 2]

"45 degree rule"

is that Kelvin?
degrees Fahrenheit?
degrees Rankine?
or degrees Celcius?

because I have to wait a LOT longer for a couple of them

...
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

[chuckakers 369]

billvon

It still works extremely well, because it relies on the assumption that winds at opening altitude are usually a similar direction but lower strength than the winds at altitude - and that is correct 99% of the time.

Not everywhere. Here in Houston (south side, nearest the coast) we often have uppers that are as much as 180 degrees from the wind direction at deployment altitude and with dramatic differences in speed as well. During some months it's quite common.

I know the "uppers only" calculation works for most DZ's most of the time, but it's important for jumpers to understand that it is not the upper winds alone that determine safe exit separation. Without a correct fundamental understanding it is entirely possible for a jumper to believe all the bases have been covered and then find themselves in a deadly situation.

Chuck Akers
D-10855
Houston, TX

[BrianM 1]

rehmwa

"45 degree rule"

is that Kelvin?
degrees Fahrenheit?
degrees Rankine?
or degrees Celcius?

because I have to wait a LOT longer for a couple of them

It can't be Kelvin. Kelvin isn't measured in degrees (it's just Kelvin, not degrees Kelvin).

"It's amazing what you can learn while you're not talking." - Skydivesg

[JWest 0]

Quote

Sorry, I should have been clearer. I wanted to know what JWest thought.

-Mark

Apparently my reply never went through yesterday. I say usually because I can't guarantee that they counted. Also its a 182 so it doesn't compare to big DZ where the exit timing is way more important. aka We don't have big ways with horizontal drift.

Jumpers aren't going to reach 45 degrees. I don't use it because it has been shown not to work. Now I'm not going to say that the method doesn't work at all. I will say that it does not work as it appears on the surface. We can all agree that more separation is better than less. The 45 method makes students get used to waiting. Since as we know the previous jumper is not going to reach 45 they should wait all day but they won't. It is also likely that they will rush their count if told to wait X amount of time. Once people get a little experience ( like 15 ish jumps) they become better at counting. When this happens they can be introduced to the counting system. Thats pretty much what happen to me. Along with all the other things that fall under the category of (not a student anymore so we do it differently). So do I think it works as a method to get proper exit separation? No. Do I think it's a way to manipulate student into waiting longer? Yes.

[kallend 1,621]

JWest

We can all agree that more separation is better than less. The 45 method makes students get used to waiting. Since as we know the previous jumper is not going to reach 45 they should wait all day but they won't. It is also likely that they will rush their count if told to wait X amount of time. Once people get a little experience ( like 15 ish jumps) they become better at counting. When this happens they can be introduced to the counting system. Thats pretty much what happen to me. Along with all the other things that fall under the category of (not a student anymore so we do it differently). So do I think it works as a method to get proper exit separation? No. Do I think it's a way to manipulate student into waiting longer? Yes.

You shouldn't ever be making someone learn something they have to unlearn later. Clearly some people never manage to unlearn it even after becoming AFFIs.

...

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

[JWest 0]

I have learned so many things that I was later told to forget because we have a better way of doing it that I would not of been able to accomplish as easily. This goes for life not just skydiving. Math and sciences are a good example of that.

Not all people are equal, or try to learn new things.

[jumpsalot-2 2]

JWest

Quote

Sorry, I should have been clearer. I wanted to know what JWest thought.

-Mark

Apparently my reply never went through yesterday. I say usually because I can't guarantee that they counted. Also its a 182 so it doesn't compare to big DZ where the exit timing is way more important. aka We don't have big ways with horizontal drift.

Jumpers aren't going to reach 45 degrees. I don't use it because it has been shown not to work. Now I'm not going to say that the method doesn't work at all. I will say that it does not work as it appears on the surface. We can all agree that more separation is better than less. The 45 method makes students get used to waiting. Since as we know the previous jumper is not going to reach 45 they should wait all day but they won't. It is also likely that they will rush their count if told to wait X amount of time. Once people get a little experience ( like 15 ish jumps) they become better at counting. When this happens they can be introduced to the counting system. Thats pretty much what happen to me. Along with all the other things that fall under the category of (not a student anymore so we do it differently). So do I think it works as a method to get proper exit separation? No. Do I think it's a way to manipulate student into waiting longer? Yes.

So ..... you are in the 182 at the exit point flying at 80 knots for exit. The uppers are 80 knots in your face. You are unaware of the upper wind speed because you never asked. The jumper ahead of you exits and quickly clears the airspace under the plane. How long do you plan on counting ?

Life is short ... jump often.

[billvon 2,380]

>Also its a 182 so it doesn't compare to big DZ where the exit timing is way more
>important. aka We don't have big ways with horizontal drift.

My first jump in Ireland there were five people in a 206. It was us (a 2 way) and a 3 way. 3 way got out first. The jumpmaster (in the first 3-way) said "winds are really strong today so get out as fast as you can before the plane gets pushed out of position!"

So it's applicable to small aircraft too. (Sometimes more so since they tend to have lower ground speeds.)

[JWest 0]

Quote

So ..... you are in the 182 at the exit point flying at 80 knots for exit. The uppers are 80 knots in your face. You are unaware of the upper wind speed because you never asked. The jumper ahead of you exits and quickly clears the airspace under the plane. How long do you plan on counting ?

So basically the winds are 180 MPH in your face? Assuming that the original 80 Knots was ground speed. Or was that supposed to be essentially zero ground speed? Rephrase your question so it's not crap. There are so many variables that it is unanswerable.

I have never experienced uppers that strong so If I was aware of them I would ask an instructor before we even left the ground.

Billvon- of course there will always be situations that contradict some statement. We are speaking generally here.

[jumpsalot-2 2]

Man you are lost ... stop giving advice.

Life is short ... jump often.

[JWest 0]

jumpsalot-2

Man you are lost ... stop giving advice.

Lol not lost, that was just a shitty question. I could go into the physics of why it's a shit question but I will spare everyone.

The advice I'm giving, use the counting method to determine exit separation. Don't use the 45 method.

[kallend 1,621]

JWest

I have learned so many things that I was later told to forget because we have a better way of doing it that I would not of been able to accomplish as easily. This goes for life not just skydiving. Math and sciences are a good example of that.

Not all people are equal, or try to learn new things.

But were you deliberately taught something that is well known to be incorrect? Is it really harder to count to 8 or 10 seconds than to eyeball a 45 degree angle that will never happen anyway? Really?

...

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