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jrcolo

Opinions on new jumper with digital altimeter?

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If you're close to brown-out under a hard spinning mal, I'd bet that it would be easier to know if you're at your decide-and-act altitude with a well-marked analog alti. than with a digital.

$.02



I'm sorry but you have no base of experience for this opinion and example.

If you've let a malfunction last long enough to make it close to g-lock, then your altitude doesn't matter anymore. What kind of dytter or wrist mount altimeter doesn't matter. What kind of cool jumpsuit you're wearing doesn't matter. None of that matters. You already waited too long to chop and are 100% behind the curve.



Since you're big on people needing to be on the "cool kids" list in order for them to even have an opinion, I'll let you read this guy's opinion. Apparently he's on the "cool kids" list. His last name is Booth.

Risk of spinning mal with g-forces not allowing you to cut-away



I think the point is (assuming your profile is correct) that the bottom line is altitude awareness no matter what type of instrument that you use. Indeed as Bill states things can happen very quickly after a poor opening followed by a malfunction. The lesson to be learned is that you should be altitude aware during 1. breakoff 2. end of your track and 3. when you pitch your PC. Analog, digital - it's only a tool. Always stay altitude aware and you don't get in a corner during a high G malfunction.

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Cool kids? Nope. Having enough experience to know that if you're worrying about altitude when you're in a hard spinning malfunction, then you've missed something along the way OR you simply don't have any experience in this sport.

Please get with your S&TA and/or head instructor at your DZ to rectify a training error that appears to have appeared.
--"When I die, may I be surrounded by scattered chrome and burning gasoline."

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From a physics standpoint, Dave is right - if you're close to graying out due to a spinning mal, you've already waited too long...



Not true.

Low orthostatic pressure and things like dehydration can cause a person to blackout (not brownout, blackout) by just standing up from a seated position. And yes, I do have experience with this. It happened to me once 15 years ago. When it happened, I did enough research on why it happened to allow me to say from my experience that it can happen very quickly, and no matter how mentally together you may think you are at that moment, your ability to process information will degrade rapidly.

When a brownout happens, a person may find that "needle-in-the-dark-area" is faster to be recognized than "is one number (constantly changing number) on a digital display greater than or less than a number that I have in my head". I've never done research on this though. But, I know that a binary visual indication is more easily recognized than a calculated piece of information. Did you ever wonder why cars have "idiot lights" on the dashboard? Why do most tachometers have a redline marking (some even have an over-rev light and an audible)? Why not just leave the tach with numbers and assume that the driver will keep track of redline specs during their visual sweep? Why not do the same with oil pressure?

I'm not giving advice. Especially not to the OP. I'm just sharing my opinion and experience. Negate it logically, but don't just say that I don't have the base of experience to have an opinion. If I'm wrong, I'll say so, but Dave's comment on my opinion was laughable. I'll leave you guys to your opinions now. I'm going to go sit with the other kids.

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learn to referance altitude based on the horizon. Its something an old skydiver told me. Both analogue and digital altimeters can fail. If your eyes fail then you shouldn't be jumping
Divot your source for all things Hillbilly.
Anvil Brother 84
SCR 14192

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Are you done being ass-hurt because someone disagreed with you?

Fact: You discussed a spinning malfunction, not physiological effects from low static blood pressure or dehydration.

Fact: The gravest dangers from a hard spinning malfunction are G-LOC or the inability to bring your arms up enough to reach your handles....which is usually followed quickly thereafter by G-LOC. This is exactly what killed Chris Martin.

Fact: Given the above, unless you've just spun yourself up in the middle of your landing pattern, you ARE behind the power curve and should be executing your EPs, not dicking around with your altimeter.
Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

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Just in case there are any UK jumpers reading this thread, I believe that there are license restrictions here on when you can wear just a digital alti. I think it's a B license, but it may be a number of jumps.

You can wear one alongside an analog, but some instructors / CCIs aren't thrilled by the idea of people wearing 2 altis because of the increase in snag points.



I would have to call bull on this one. Not sure what your reference is for assuming this, but AFAIK this is one thing that the BPA have not regulated yet!

From the Apr 08 Ops Manual:

4. INSTRUMENTS

4.1. Altimeters must be worn by all Student Parachutists (other than Tandem Student Parachutists), jumping Piggyback equipment. Also altimeters must be worn by parachutists carrying out planned delayed openings of 15 seconds or more, (other than Student Parachutists jumping Traditional equipment, on their first successful 15 second delay).

4.2. The minimum instrument is a serviceable non-sensitive visual read out altimeter, securely mounted in a suitable position.

4.3. Instruments should be positioned so as not to interfere with the use of other parts of the equipment.


You only need to have a serviceable non-sensitive visual read out altimeter. Some centres are actually starting to use digital altis for RAPS.
***************

Not one shred of evidence supports the theory that life is serious - look at the platypus.

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Denete - experience base listed:
Jumps: 22
License: Student
In sport: 1 years

Dave and Mike are correct (want to make that your sig, guys). If you are greying out for whatever reason in a skydive, you shouldn't be dicking around with your altimeter.
...

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

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Denete - experience base listed:
Jumps: 22
License: Student
In sport: 1 years

Dave and Mike are correct (want to make that your sig, guys). If you are greying out for whatever reason in a skydive, you shouldn't be dicking around with your altimeter.



;) See sig... :P
Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

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You just contradict with yourself.

No, I'm not.

With a regular clock, there's not much of the piechart effect as there is with the Altimaster. So I read an analog clock at a different speed than I read the altimaster.

But, when you read the history of the Altimaster's, it is true that the people behind the Altimaster designed the face to resemble a clock. But there's the coloring at typical decision altitudes. If I see the arrow exactly between the colored area and the 6 o clock, I know it's the 4500 breakoff (typical small RW breakoff). If I see the arrow just about touching the colored area, I know it's time to pull if clear.

However, I am also a good English speed-reader while still retaining sufficient contextual information, so I am pretty comfortable at sub-second quick chance glances of numeric displays. I find I process numbers better than analog displays, but Altimaster compensates by providing the pie-chart effect (The yellow and red zones). In an actual computer test, I can read a digital clock flashed 1/60th of a second, but I cannot read an analog clock flashed 1/60th of a second. (Persistence of vision allows reading 4 numbers post-mortem in the following fraction of a second, assuming I am already glancing in the exact direction where the numbers briefly flashed) Tests show that it's truth that people can read a limited number of digits purely by persistence of vision alone, for a numeric display instantly flashed -- if they're glancing at the general direction and expecting to read numbers. (For sake of context: The quick urgent glance at an altimeter while you're trying to save your life in an emergency situation). This is because my brain is trained to recognize numbers very quickly. Thus, I only need a near-instant glance at a digital alti and know my altitude from simple persistence of vision.

Yes, let me also defend another perspective from naysayers who may respond with the calculation perspective: Yes there is, on a population average, slightly slower speed of comprehension of estimating differences (i.e. 5200 versus 7500 on digital-versus-analog alti, or 12:15 versus 12:40 on digital-versus-analog clock) on digitals than analog. Yes it may be slower than knowing the needle moved a little over two ticks on an analog. But, even this isn't universally true, and sometimes this is less important than knowing how close you are to impacting the ground. (i.e. a simple bigway jump where there's already a central breakoff signal and you're already using an audible, and that in an emergency situation when you finally pull, certain people will indeed survive better with digital -- then that's when the digital versus analog will matter for that particular person). Sometimes the superiority of digitals are very dramatic for a small niche of people: People who already know their addition tables, do fare well though -- i.e. People who instantly know the difference between 5 and 7 is always 2. Now, if I was graying out, and my Altimaster did not have the piechart effect, I'm going to trust a digital more than an analog to know if I hit my hard deck under a confusing mal, because I take less time reading a digital display -- I don't even need to continue staring at it - I only need a quick glance, and read it 1/2 second later from my persistence of vision. The only reason the analog is faster is because the hard deck is conveniently red-colored, that only requires an instant glance too as well. (But what if the hard deck for a specific type of parachuting activity, such as freefly, especially as a deaf guy it's hard for me to rely on an audible except for the Optima LED?) Anyway, many people agree that they read a digital faster. But yes, some operations are faster with a digital and some operations are faster with an analog - people process different types of info at slightly different speeds. Some people actually process almost all operations on a digital than an analog (even instantly knowing 75XX feet and 52XX feet is about 2.3Kfeet different without needing to math calculate. Just good addition-tables memory). Some people never grew up with an analog-dial telephone so many people haven't developed brainpower to process circular-analog display, especially if they're heavily schooled on numbers to the point where they've got all their 100/100 addition table memorized (good for the upper 2 digits of the digital alti). But yes, this is the exception to the rule, and some people only process digitals faster for some operations (not all operations) than analog. Almost everybody knows when they glance (either digital or analog) at 6000 feet for a flatfly jump that requires a 3000 feet altitude, they know they have approximately 20+ seconds before pull - the question now becomes, can they survive better in an emergency situation with the digital or the analog? Hard to say, but I am willing to bet big money that the answer is not 100% universally the analog. I say: varies by person.

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You are drifting. Analog and digital readout is studied in ergonomics and psychology, it has nothing to do with computers or etc.

You're contradicting yourself. Many reputable institutional classes speciallizing UI design has a lot to do with ergonomics and psychology. Have you studied Apple books recently? Have you taken any courses in this? I have. Have you?

Most people do function better with certain UI than others, but what I am saying that there's no cookie-cookier "one size fits all" quickest way for everybody. Exactly the same thing applies for analog versus digital.

I reiterate that I side with the school of thought that some people, on average, function better with analog, and others function better with digital. On average, yes, it bias towards one end but I disagree with the assertion of the one-size-fit-all approach. Personally, I function okay with either technology and I can see the advantage/disadvantages of the two...

Some people have very good number-relationship memory. They glance 5XXX feet in less than 100 milliseconds and know it's 10 seconds to pull time. (This is true: In tests, people can read a digital clock that has been flickered on-and-off in less than 1/10th of a second in front of them -- the digital altimeter with a 4 digit display is the same number of digits.). Instantly knowing that 7[0-4]XX feet from 5[0-4]XX feet is around 2000 feet, without needing to calculate or trying to remember. (It's just simple hard-wired addition tables in your memory, knowing the numbers 5 and 7 have a difference of 2). True, what you say may be a travesty to the poor level of numbers ability of many people today, analogs are much much better in this case.

What's definitely true, is that not 100% of people read digitals faster than analogs. However, some properly literate people read digitals much faster than analogs.

Yes, analogs are better in general (when not knowing what's best for the person), but this is not universal. And it even varies by discipline. A certain swooper might prefer analogs for very excellent reason, but that a certain RW flyer performs more flawlessly with a digital, and another may have no real preference. People revert to their childhood mode of oepration in an emergency situation (read analogs faster), but many certainly didn't grow up around analog dials as a kid, and would survive an emergency situation better with a digital, especially if they already have a reasonably good ability to glance numbers (an addition table memory is useful so that NO mental calculating is needed). Certain things are totally effortless for some while for others it is not. In fact, I seem to be a digital-era person instead of analog-era: I seem to somehow struggle badly with a circular compass, but I instantly function with a digital-degrees readout display or ruler. (Hmm, I bet you can stir up some interesting debate with airplane pilots about what compass they prefer)

Sorry, I get defensive, but when someone disputes correct information incorrectly, I will throw some more facts. If we wish, we can begin posting references to educational studies and all (I'm ready), but I think that's going overboard and will just make both of us unpopular to others. I declare I'm already going overboard, so that's where I get off this train.

What's important is that we have fun skydiving, and safe skydiving. This subject is a dead horse. There are friends on dropzone.com to enjoy skydiving with.

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