Decision Alt vs Hard Deck

[fcajump 153]

On 10/27/2022 at 4:33 PM, riggerrob said:

I disagree with the notion of only deploying a reserve if you find yourself below altitude "X."

That tactic may have been relevant when round reserves were fashionable, but when was the last time you saw a round reserve in opened in the air?

If someone swoops through my main and shreds the left side at 300', it is clearly too low for a cutaway, but adding fabric might help.
I'm not saying at that point that you have a "normal/every-time" answer to the problem... just that there is an altitude that is too low to cutaway, too high to survive, and mid-air rigging/throwing more solutions at the problem is about all you've got left until the PLF.

JW

 

[al05r 2]

I also hate these terms.. even with consistent definitions, it's very easy for new jumpers to just flip the jargon around, and understand the wrong thing. 
I think this is one of those areas where the sport's military drilling style of training sometimes falls short.

Whenever I get asked about "hard decks" or "decision altitudes", rather than just spit out numbers I just try to reply in complete sentences, eg

I will deploy my main at minimum at X. If I find myself in freefall below that I will deploy my reserve directly. If a malfunction looks fixable I'll try until Y,  but then chop immediately no matter if I've almost solved the problem. I will not cutaway a mal below Z, I'll either ride it in or deploy my reserve in addition to the main. It's good to think about these and choose your own altitudes, but also understand that depending on the day, place, and jump some may need to be adjusted.

[sfzombie13 307]

2 hours ago, al05r said:

I also hate these terms.. even with consistent definitions, it's very easy for new jumpers to just flip the jargon around, and understand the wrong thing. 
I think this is one of those areas where the sport's military drilling style of training sometimes falls short.

 

what are your suggestions to replace them?  it's very easy to flip the jargon in the definitions the way they are, but they don't even say cutaway and are about as easy to understand as a legal definition of something.  students get lots of things mixed up, that's why we need to continue to drill them on the things they need to know to survive, not change the terms for them.  we need to change the official definition for sure, but not the words themselves.  you don't change something that has worked for 99.995% of the group so that a new member doesn't have to learn the terms we all use.  not unless you have a really good replacement in mind that everyone else will remember or you just trade the problem from one group to another.

[al05r 2]

I don't particularly care about replacing them - it's normal for written words to be misinterpreted or misunderstood.
In my experience the more you try to remove ambiguity from text, the more "legalese" that text becomes.

So, instead of assuming another person has the same definition in mind for "hard deck" as I do, I think its more effective to use a few more words and point out the significance of the various altitudes and the actions/decisions associated with them.

It takes but a few seconds, definitely less than looking up the definition in the SIM.
Once the concepts are clear, the nomenclature (should) be easier to understand.

[sfzombie13 307]

i just don't see the ambiguity between hard deck and decision altitude.  hard deck implies it's hard, no changes.  decision altitude implies that you make a choice, the only time you choose between cutaway and don't cutaway.  the numbers can change as you say, depending on lots of things, but that is after the student learns the definitions.  if we need more words to convey the meaning, i'm all for it though.  just because i understand it doesn't mean everyone does.  the way it is sucks pretty good though.  overall, i agree with you.

[nwt 131]

15 hours ago, sfzombie13 said:

i just don't see the ambiguity between hard deck and decision altitude.

I find this at odds with the rest of what you've been saying

16 hours ago, al05r said:

it's normal for written words to be misinterpreted or misunderstood.

normal doesn't imply safe or acceptable

[sfzombie13 307]

6 hours ago, nwt said:

I find this at odds with the rest of what you've been saying

 

nice.  i had to look up ambiguity to make sure i used the word correctly.  then i had to go back and read the entire thread to make sure i wasn't hallucinating or playing devil's advocate on something.  after all of that i am pretty sure that i have been saying all the time that the two phrases are pretty  clear to me, and included what i thought the definition should be.  i said that the uspa definitions are clear as mud, meaning that they are hard to understand, and they don't even use the term "cutaway", which is what they are supposed to be referencing.  perhaps that is what you mean. 

[nwt 131]

3 hours ago, sfzombie13 said:

nice.  i had to look up ambiguity to make sure i used the word correctly.  then i had to go back and read the entire thread to make sure i wasn't hallucinating or playing devil's advocate on something.  after all of that i am pretty sure that i have been saying all the time that the two phrases are pretty  clear to me, and included what i thought the definition should be.  i said that the uspa definitions are clear as mud, meaning that they are hard to understand, and they don't even use the term "cutaway", which is what they are supposed to be referencing.  perhaps that is what you mean. 

Sorry I didn't mean to make you go back and read a bunch of stuff. Your definitions seem clear but both seem to mean the same thing to me, which I don't think is intended? I've said this before.

[sundevil777 93]

22 hours ago, sfzombie13 said:

the two phrases are pretty  clear to me

Quite right, it isn't obvious when things are ambiguous, which makes it so dangerous.

I think the use of the term "decision" in one of the terms, but not the other, because the hard deck doesn't involve a decision or whatever...is awful.  Only a committee of overeducated experts could get such a lousy result designing the terminology which ought to be used.  

[sfzombie13 307]

except it isn't ambiguous at all.  the word 'decision' in the first one says you make a decision to cutaway or not, which could be phrased like "when you reach this altitude, make a decision to either cutaway what you have or ride what you have to the ground".  hard deck says nothing about a decision, but rather SHOULD say something to the effect of "do not cutaway your main below this altitude.  deploy your reserve and if you need to, then cut the reserve away."

i just do not see how anyone can mess this up.  they are completely different terms, and they mean completely different things, uspa definition notwithstanding.  this way we can modify what we teach new students while keeping the terms the same as every other student has heard.  uspa needs to clarify the terms, and then update the training to ensure that all instructors use the terms correctly.  sounds like a good safety day gimmick.

 

[sundevil777 93]

5 hours ago, sfzombie13 said:

i just do not see how anyone can mess this up.  they are completely different terms, and they mean completely different things, uspa definition notwithstanding.

If asked "what is your hard deck?" the reply of many will be their decision altitude.  If asked for both, the distinction is forced. 

[sfzombie13 307]

17 hours ago, sundevil777 said:

If asked "what is your hard deck?" the reply of many will be their decision altitude.  If asked for both, the distinction is forced. 

that is a result of poor training, not poor terms.

[sundevil777 93]

21 minutes ago, sfzombie13 said:

that is a result of poor training, not poor terms.

How shall we fix the poor training, by telling the instructors to do it better?  

How shall we prevent people from giving their decision altitude when asked what their hard deck is? 

The misunderstanding has existed for as long as the terms have been used.  The 3rd post especially shows how this has persisted.  The use of these terms is a significant part of the misunderstanding.



 

[sfzombie13 307]

1 hour ago, sundevil777 said:

How shall we fix the poor training, by telling the instructors to do it better?  

How shall we prevent people from giving their decision altitude when asked what their hard deck is? 

The misunderstanding has existed for as long as the terms have been used.  The 3rd post especially shows how this has persisted.  The use of these terms is a significant part of the misunderstanding.



 

pretty sure i've been asking anyone for a suitable substitute.  you know, one that does the job of communicating the difference between decision and no decision without also throwing off the thousands of skydivers who have gotten it right.  you fix the poor training by retraining.  repetitions of the terms until it is understood.  much easier to do with newer students, but not that hard to do for everyone. 

 

yeah, no way we can make it any more clear than having the word "decision" in one term and not the other.  but again, i'm open to suggestions. 

[wmw999 2,116]

Most people don’t really think they’re going to take a significant amount of time to go from decision to action. So to them the decision altitude is the action altitude.
Maybe instead just make an arbitrary definition of “decision altitude” as being 500 feet (or some other number) above the execution altitude. Or call it execution altitude. 

Wendy P n

[nwt 131]

11 hours ago, wmw999 said:

Most people don’t really think they’re going to take a significant amount of time to go from decision to action. So to them the decision altitude is the action altitude.

I think this is what I've been trying to say.

[sfzombie13 307]

and that is the failure of the training.  when a student starts jumping, they don't know anything.  if they get this idea, they got it from not having the real situation drilled into their heads.  they two altitudes are a bit apart, and this needs to be emphasized.  every skydiver at my dz knows the difference, maybe we train them better, maybe they're smarter, maybe we got lucky. 

making it an arbitrary number is the worst thing we can do.  as mentioned in this thread, the number can change based on lots of things.  at my dz we use seatbelts and helmets in the plane until 1500' not the 1000' in the sim due to hills around the dz that are about 500'.  this also raises the others, and most of us have raised our aad firing altitude just in case.  maybe having a variable altitude is what makes our jumpers more aware of the correct terms.  perhaps we should emphasize this with students, and not stop emphasizing it until they are d licensed.  that would solve the problem, just randomly talking about the two terms constantly.  

Edited November 7, 2022 by sfzombie13

[wolfriverjoe 1,340]

2 hours ago, sfzombie13 said:

...  at my dz we use seatbelts and helmets in the plane until 1500' not the 1000' in the sim due to hills around the dz that are about 500'... 

Lots of places have raised 'helmets & seatbelts' to 1500, even flat places.

My understanding is that:
#1 - nobody's going to get out that low.

#2 - the amount of time you have from an engine failure to impact from 1000' is a LOT shorter than most realize, and the amount of time it will take to find & reattach the seat belt is a LOT longer.

While I understand we need a 'short & simple' term for these altitudes, I don't like them (no, I don't have any viable alternatives).

I've always clarified them. 

"Decision Altitude" is the lowest you will "decide to stop fucking around with a questionable canopy and chop it". 
As noted previously (or maybe in a different thread), it's a minimum.
Making that decision at a higher altitude gives one more options, more time, more altitude to deal with any potential issues after the chop.

"Hard Deck" is simply the lowest altitude I will pull the cutaway handle. 

They are different because of the potential to have a situation arise below decision altitude (canopy collision is the one that comes to mind, but there are others).

I really dislike 'hard deck' because it is a specific term, with a specific purpose. It was misused during the original Top Gun, and has been misused by those outside of airplanes ever since.

What it is is 'simulated ground'. That is, if you 'bust the hard deck', you're (administratively) dead.
In the movie, when both Jester & Mav went 'below the hard deck', they should have been 'declared dead' for CFIT (controlled flight into terrain). 

For civilian aerobatic pilots, it's the same thing. Airshow guys work quite close to the ground. They get to that point by having a 'hard deck'. So if they (for example) pull out of a loop 'below the hard deck', then they would have died had they done that for real.

[pchapman 261]

Side conversations:

a)  I'd say that Hard Deck in other forms of aviation isn't always the simulated ground level. It may just be the level you plan to never go below, because that would imply a failure of your flying the maneuvers as you wanted. So I've seen a hard deck of 1500' mentioned for Sportsman level competition aerobatics.... because that's the minimum you are allowed to fly at, in that category, without getting severely penalized (like scoring zero for your whole flight).  It isn't as if a Sportsman level aerobatic competitor is pretending to do low level aerobatics simulating the ground at 1500'.  It is just the "don't ever go there!" altitude.

b) If we have a Hard Deck in skydiving, then logically speaking there must also be a Soft Deck, perhaps as the desired but not absolutely minimum cutaway altitude... which is maybe the Decision Altitude!  But since nobody every says Soft Deck, better just ignore that idea entirely instead of trying to change the whole sport's terminology.

Back to the main topic:

I don't have good answers either to this whole thread, but if talking to a newbie jumper I'd probably say something like: 

"The Cutaway Decision Altitude is often just abbreviated to the Decision Altitude when talking about malfunction emergencies. It is the minimum altitude at which you normally would want to be cutting away. Cutting away is also known as Breaking Away. You would prefer to make the decision to cut away, and actually do so, higher than the Cutaway Decision Altitude. But you can cutaway lower if you somehow accidentally find yourself lower than the Decision Altitude, and have a malfunction. Then the absolute minimum altitude at which you would ever cut away is the Cutaway Hard Deck, often just abbreviated as the Hard Deck when talking about malfunction emergencies."

 

 

[sfzombie13 307]

that would make my head spin.  it makes a good comedy skit in my head, like fandango or some crap.  why not just say the decision altitude is where you make a decision to cutaway or not.  hard deck don't cut away, ever, but deploy your reserve if you have to and do a canopy transfer if you have to (downplane or some other scenario).  i mean, whatever gets the message across, but if we keep it simple and try not to change things too radically or all at once, we can absolutely substitute anything that makes sense.  i just haven't heard one, except maybe soft deck, but we are skydivers so you know how class is going to go with those terms...

[nwt 131]

29 minutes ago, sfzombie13 said:

why not just say the decision altitude is where you make a decision to cutaway or not

because deciding to cut away isn't enough, you need to actually do it

[sundevil777 93]

57 minutes ago, sfzombie13 said:

you make a decision to cutaway

It has been asserted there is obviously no decision made at the hard deck.  Perhaps that is the source of the argument.

If any of us tried to put on paper a hard deck algorithm, there would be diamond shaped decision boxes, correct?  You could call them if-then boxes if you want, but a person must do the evaluation of the situation and make the correct thing happen as must be done at decision altitude.

[sfzombie13 307]

3 hours ago, sundevil777 said:

It has been asserted there is obviously no decision made at the hard deck.  Perhaps that is the source of the argument.

 

there is no decision whether to cutaway or not.  that is why it is a hard deck, you DO NOT cutaway.  no decision to be made, just ride your main in.  deploy your reserve as needed but DO NOT cutaway first.  yep, that's where the argument is, no room for a decision in my line of thinking. 

[sundevil777 93]

1 minute ago, sfzombie13 said:

there is no decision whether to cutaway or not.

A person must realize their situation and apply the right action.  There is evaluating and responding going on.  Many will see that as synonymous with a decision. 

Decades worth of evidence supports the ambiguity of the terms.  An outsider would conclude new terms would likely work better than a new effort to train better.