Re: [beezyshaw] Fatality - 30 july 2006 - Romania

[bob.dino 1]

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Even though you deploy at around 1500, with even a slightly snivelly canopy you go whistling through a thousand feet with a partially inflated main. Well, at a thousand feet the AAD says "do it". So even though your main opens right at that instant, at about 700 ft your AAD will cut the reserve loop. And the reserve loop is cut a couple of hundred feet lower than you got a fully inflated main! The point to remember here is that just because you get your main opened does not prevent the AAD from activating. Once the device decides to fire, there is no stopping it.

A Cypres is designed to fire at ~750ft, if you're stable on your belly. When stable on your belly there's an area of low pressure around your main container (the burble). If you're vertical, there's no low pressure area there and a Cypres can fire as high as 1000ft.

So, if your snivelling main stands you up but doesn't slow you down below 78mph at 1000ft, you're likely to have a Cypres fire.

[beezyshaw 0]

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A Cypres is designed to fire at ~750ft, if you're stable on your belly.

My understanding after several conversations with my good friends at SSK and Airtec is that even though the CYPRES "fires" at the altitude you say, it makes the decision to fire somewhat higher than that, and regardless of how slow you get between that decision height and the actual firing height, nothing will stop AAD activation. Now, the fatality discussed in this thread involves the Vigil, not a Cypres, but that's probably not an important difference; I assume the two AAD's are very similar in that regard.

[billvon 3,118]

>My understanding after several conversations with my good friends at
>SSK and Airtec is that even though the CYPRES "fires" at the altitude you
>say, it makes the decision to fire somewhat higher than that, and
>regardless of how slow you get between that decision height and the actual
>firing height, nothing will stop AAD activation.

I've had the same discussion, and the cypres does not "decide to fire" and then fire later. When its firing criteria are met, it fires. If they are not met, it doesn't fire. Since the pressure over your back increases when you rotate belly-to-earth, it can fire higher than 750 feet. This leads people to think that it "decides to fire" at 1000 feet, when in fact it is just firing at what it thinks is 750 feet, as always.

[beezyshaw 0]

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I've had the same discussion, and the cypres does not "decide to fire" and then fire later. When its firing criteria are met, it fires. If they are not met, it doesn't fire. Since the pressure over your back increases when you rotate belly-to-earth, it can fire higher than 750 feet. This leads people to think that it "decides to fire" at 1000 feet, when in fact it is just firing at what it thinks is 750 feet, as always.

Yes, I retract my earlier statements about a "time delay". I now understand that it is only 10 milliseconds between the activation parameters being met and the loop being cut. That is instantaneous. The "urban myth" that I had believed to be a time delay is more related to pressure changes as your canopy sits you up during deployment, which can tell your AAD you're actually speeding up instead of slowing down. SSK just explained to me that, for instance, a CYPRES will fire at around 1000 ft if you're in a vertical freefall position but will fire at about 750 ft if you're belly flying because of the burble created in that body position.

[mjosparky 4]

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for instance, a CYPRES will fire at around 1000 ft if you're in a vertical freefall position but will fire at about 750 ft if you're belly flying because of the burble created in that body position.

I believe that is exactly what bob_dino said in his post.

My idea of a fair fight is clubbing baby seals

[Sockpuppet 0]

Would it not be a good idea for a AAD to be designed with 2 extra cutters attacked the to 3 ring system. Instead of pulling the cord out releasing them it could cut the cord.

This pic is quite good: http://en.wikipedia.org/wiki/Image:3ring.png

I.e. on the white para cord style stuff. If the AAD decides to fire the reserve it can also cut the cords so if you do dump late then all the main is going to do is sail up into the clouds.

If it fires the same time as the closing loop then the main shouldnt be entangled as it will be above the reserve and if the main is still in the container and you dont pull the main it should stay there untill the ground.

------
Two of the three voices in my head agree with you. It might actually be unanimous but voice three only speaks Welsh.

[wmw999 2,588]

Probably not. It would increase the complexity a lot. In a life-critical fail-safe system (i.e. failures don't leave you worse off), that would mean a lot of stuff.

I posted about some of the considerations here. The only reason I'm linking it is because, well, I used a lot of big words in that post.

Wendy W.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[mjosparky 4]

No.

My idea of a fair fight is clubbing baby seals

[billvon 3,118]

> Would it not be a good idea for a AAD to be designed with 2 extra
>cutters attacked the to 3 ring system. Instead of pulling the cord out
>releasing them it could cut the cord.

An early design concept for the cypres provided just that functionality. They ended up not using it because it would greatly increase the odds of a misfire killing you. (Imagine being "cut away" at 200 feet.)

[riggerrob 643]

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> Would it not be a good idea for a AAD to be designed with 2 extra
>cutters attacked the to 3 ring system. Instead of pulling the cord out
>releasing them it could cut the cord.

An early design concept for the cypres provided just that functionality. They ended up not using it because it would greatly increase the odds of a misfire killing you. (Imagine being "cut away" at 200 feet.)

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Correct!
However, a few military freefall bundle systems use a similar system to deploy main canopies. Typically, bundles are rolled off the ramp of a C-130 and a static-line deploys a drogue. When they reach deployment altitude, an FXC pulls a pin from the 3-Ring release, while more modern systems use a Cypres cutter to cut the white nylon loop, releasing the 3-Ring at the bottom of the drogue bridle.
Most of these systems have quick-chance white loops similar to CT-7 military freefall rigs.

[Sockpuppet 0]

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> Would it not be a good idea for a AAD to be designed with 2 extra
>cutters attacked the to 3 ring system. Instead of pulling the cord out
>releasing them it could cut the cord.

An early design concept for the cypres provided just that functionality. They ended up not using it because it would greatly increase the odds of a misfire killing you. (Imagine being "cut away" at 200 feet.)

Now a cutaway at 200 feet is really going to ruin your day but how often to AADs misfire? More than once would be too much in this situation, but as the electronics get better maybe they could use GPS to work out your height above the ground +/- 10 meters with a traditional back up maybe someday allowing this tech to go into production as an advanced AAD.

------
Two of the three voices in my head agree with you. It might actually be unanimous but voice three only speaks Welsh.

[mjosparky 4]

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> Would it not be a good idea for a AAD to be designed with 2 extra
>cutters attacked the to 3 ring system. Instead of pulling the cord out
>releasing them it could cut the cord.

An early design concept for the cypres provided just that functionality. They ended up not using it because it would greatly increase the odds of a misfire killing you. (Imagine being "cut away" at 200 feet.)

Now a cutaway at 200 feet is really going to ruin your day but how often to AADs misfire? More than once would be too much in this situation, but as the electronics get better maybe they could use GPS to work out your height above the ground +/- 10 meters with a traditional back up maybe someday allowing this tech to go into production as an advanced AAD.

If they work at real hard they might come up with a gadget or gismo to do everything for you and you can just call the jump in from home.

People already bitch about the high cost of jumping and adding another layer of complexity to safety devices sure ain’t going help bring it down.

My idea of a fair fight is clubbing baby seals

[mdrejhon 8]

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An early design concept for the cypres provided just that functionality. They ended up not using it because it would greatly increase the odds of a misfire killing you. (Imagine being "cut away" at 200 feet.)

The design might be rethought for certain flyers under experimental tiny canopies (sub-70sq feet canopies). This would save unconscious people going down in an uncontrolled high-G spinning linetwists. Because spinning linetwists are already beyond cypres firing parameters, an automatic cutaway followed by a reserve ride would occur.

I noticed an old dropzone.com thread suggesting this, where someone went in sometime under a small parachute not designed to be landed (A 21 square feet Xaos 21 I think -- yes, 21 square feet, not to be confused with the model number 21.)

[billvon 3,118]

>The design might be rethought for certain flyers under experimental tiny
>canopies (sub-70sq feet canopies).

If you really want to do that, get a tandem two-cutter cypres for the main and a standard expert cypres for the reserve. No new hardware required. You still have the problem of pulling tens of G's for a few minutes; that may not be survivable to begin with.

[billvon 3,118]

>but how often to AADs misfire?

I've seen 3-4 happen in the air for no apparent reason. Last one was a cypres 1 misfire due to landing near an airport radar installation; it fired at about 50 feet. It would really suck to get cut away at that altitude.

>maybe they could use GPS to work out your height above the ground
>+/- 10 meters with a traditional back up . . .

Seeing the trouble we have getting GPS to work even on moving trucks, I think that might be easier said than done. Keep in mind that skydivers start inside airplanes where you can't receive GPS, and even in good hot-start conditions it can take a GPS 30 seconds to acquire.

[riggermick 7]

Now a cutaway at 200 feet is really going to ruin your day but how often to AADs misfire?



Not necessarly, an RSL equiped rig with a properly packed reserve should be "functionaly open" well within 200'. @ 100' all bets are off. That being said it's still an unworkable idea, it presents more problems than it solves. Remember the KISS princible (keep it simple, stupid!), there's a lot to be said for that maxim!!!.



Mick.