pchapman

For what it's worth, I found another document from SSK that mentions the altitude compensation* also from 15+ years ago: http://www.cypres-usa.com/cyp13.htm * altitude or pressure or body position adjustment, correction, compensation, allowance, variance, differential, whatever term you prefer

A few manufacturers make the status of the white loop more easily seen by either a) having a bit of the bar tack stick out below the confluence wrap ("we didn't forget the bartack"), or b) have the very top of the white loop visible at the top of the confluence wrap ("the white loop isn't slipping"). But this is relatively uncommon.

Cypres must compensate for the burble -- even if they ignore the whole issue in their manuals! As previously posted in a link, Cliff Schmucker of SSK wrote, in the document on the SSK site: The NTSB report was written by people who don't understand skydiving and missed that point.

So "USPA's" reference is to an SSK document that suggests +300 ft for the Cypres. Thanks. Anyone got an even better source from SSK or Airtec directly about their burble compensation?

Add +260 to the Cypres too. (It isn't unfortunately mentioned in the manual, unlike for the Vigil, but it is also a factor.) So it is Vigil 840+260=1100' Cypres 750+260=1010' While it could be the plane slowed down just enough after the Vigil fired but before the Cypres would have, I think there's suspicion that the 'hair trigger' Vigil may have fired off in a situation where the Cypres wouldn't. Whether the aircraft was truly dropping over 78 or 79 mph, in its spin or whatever it was, I'm not sure.

Again I'm thinking this sort of situation could be just one of miscommunication, plus a little defensiveness on the part of Airtec. Airtec will have seen plenty of cases where someone says "it just popped!" where it later turns out "uh, I guess I did really pull way lower than I thought". Whether it is because of a good Cypres track record, or excess pride in their own gadget, maybe Airtec after an incident says that the AAD probably fired due to a low main deployment. That's their opinion, or verdict, or whatever one wants to call it. If the jumper still strongly disagrees with that, then they need to provide additional information about the incident, and need to get that AAD sent in for analysis. If the AAD isn't sent in, Airtec thinks everything is all hunkey dorey, all fine, since they don't hear anything more; no complaints. They log the AAD firing as just another low-pull 2-out. Meanwhile the jumper goes away pissed off that he's been dismissed out of hand, and starts telling his friends about Airtec coming up with a magic explanation without ever seeing the unit. Years later here we are arguing about it and having trouble distinguishing fact from fiction. P.S.- I checked and was told that Airtec still has the Moscow ground firing incident (the original thread topic) under investigation and is trying to get additional info about what happened from those at the DZ. Edit: P.P.S. - Despite the big improvements made by AAD manufacturers to overcome static electricity issues, and given that the Cypres may not have recorded setting off the cutter, I gotta wonder how cold and dry the air was on that February day in Moscow. Might be on the upper end of bad days for static charge buildup.

Interesting that your way worked well enough. I figured the idea of the big FXC plate was to provide stiffness, to ensure that the pin got pulled out, rather than the FXC housing being pulled towards the pin. I suppose that with any reasonably well filled main tray, you found that the pin would pull, rather than compressing up the soft flap?

Maybe there was some honest confusion in that case about which unit Airtec had? Even if one is suspicious about Airtec, would they really think it worthwhile to issue a statement about testing a particular unit when a DZ can show they still have it sitting in their hands and not at Airtec? What did Airtec say after actually receiving the unit? If someone still had the unit number written down, I'd guess that Airtec would still have their records from the time. It's tough to figure these things out years and years later...

My initial thoughts: I also kind of snicker at the idea that one needs all these beeps to be able to skydive and fly a pattern. And it's true, you don't, and I'm against anyone who thinks they are necessary or the "proper" modern way to do things. But I don't see a lot of harm in Brian's ideas. He's advocating under-canopy altitude alerts as a useful addition to normal practice. The beeps don't force you to turn onto base as soon as you hear the 500' beep or start your swoop turn at the 670' beep, but are a reminder of the altitude. I do everything under canopy, including amateur swooping, with a big old analogue Altimaster on my wrist. It certainly takes some time to stare up at it and figure out what my altitude is when the last 1000' is a small section of the dial. Compared to that, I was going to write about the benefits of keeping "eyeballs out of the cockpit" with a beeper, but now that I actually looked at Brian's article, it looks like that's what he's preaching anyway. In many ways, under-canopy altitude alerts are far less hazardous to over-rely on than freefall altitude alerts (which have been endlessly debated). 1) In freefall, waiting for the beep without trying to be altitude aware is clearly dangerous. Under canopy, if you just wait for the beep to turn crosswind or final, and miss it, you just sail off a little further under canopy and don't land quite where you want. Sure you can get yourself into bad terrain, but far slower than the ground approaches in freefall. 2) Under canopy you should already be actively watching your path relative to the ground (in addition to others in the air nearby). That's different than in freefall where you focus on the jumpers you are with, and are often not looking at the ground at all. So the beeper does not become your sole reference. 3) Beeps under canopy don’t act as straightforward commands like in freefall, to breakoff or to pull. Under canopy, they are basically saying, "You are now at the altitude where you normally do such and such a turn -- but you have to decide that for your self now, depending on where you are over the ground." The alerts are more advisory in nature. There probably will be some discussion about how best to introduce these gadgets to newer jumpers.

Not everybody says that. Following some people's recommendations, you would never want to talk to anybody about anything. Never talk about personal finance without a certified financial advisor. Never talk about food except with a nutritionist. Never talk about getting along with your boss without a psychologist and PhD in Organizational Behaviour. Never discuss your drop zone's aircraft maintenance without an aircraft maintenance engineer. Never discuss how to flare your canopy without Brian Germain personally present. It isn't that a professional wouldn't be useful, but they aren't the only source of information. And of course, never listen to anyone, ever, on the internet.

I'll call bullshit on the bullshit. You don't need psychobabble to learn the technical aspects of canopy flight. If you're having fear issues as a student, sure. Plenty come to dz.com for advice on such issues. Now I don't disagree that some understanding of psychology is can be useful in different aspects of life, including learning effectively or dealing with stress. But jeez, do you really need therapy to learn how a canopy flares, or different approaches to flying landing patterns? Brian knows about psych, and likes to have it in his course. Fine. But some just don't want to be paying for that.

The free-from-medications thing is usually just a legal cover their ass move by the drop zone. Just like having to sign that you have no unhealed injuries or infirmities. So if you have a weak ACL from an old injury and damage it on landing, they have a defense against getting sued. Clearly one wants to be reasonably healthy with no large risk of major side effects. As with a lot of medications, sudden changes in dosage or type of medication is a risk factor, but if on something at a steady dose, you and your doctor should have a good idea if there's any significant impairment. But I'm not sure what the FAA formally wants of "just" tandem passengers these days. A doctor may know nothing about skydiving (or drop zone waivers), so in a way they are as useless to ask as strangers on the internet. But they should have an idea if someone is fit to engage in active sports, or drive a car -- good general proxies for ability to skydive.

Yeah, it was at Skydive Toronto last October. I wasn't able to make it to do camera that day. The footage was used for this appearance of Shania on the brand new Oprah Network, also apparently timed to match up with Shania's new book. I think it was just a badly timed flare. Haven't seen the video yet to see how badly though! Some instructors are generally decent and reliable but not everyone is at the top of the game.

Mind you they don't say they DISAPPROVE either, just that they don't APPROVE.

I never met Martin H.-T., but here are a couple pics from a memorial facebook page. Appears to be a fully articulated Mirage with full width, double thickness chest strap, with foldback. Of course I don't know what he was jumping at the time but these are from a bunch of recent photos where he has that jumpsuit and rig. The second photo isn't as high quality but shows that the rig is better fitting than one might guess from the under canopy, chest strap loosened photo.

So this would be about the May 8, 2011 accident that had little revealed about it in the Incidents forum: http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4116896;

Re: gasoline & baffles Ah, so there was a trick to it. I don't recall the trick being talked about at the time. (Or am I wrong?) The videos in effect created an erroneous impression of the flammability of nylon. Deceptive bastards. But scientific standards don't hold up in entertainment tv...

Just leave the batteries in. Internally there's an aneroid capsule and it depends on making electrical contact with the electronics. But I'm guessing the electronics are always powered, so it has a sense of sequence and can interpret a series of events (e.g., Being set on the ground, then passing the set altitude going up, and then going down through that altitude, with the aneroid making or breaking contact at those points). So the Dytter should be like some modern device that stays in a sleep mode all the time (some iPods). A better analogy is probably a watch with an alarm. Perhaps someone with more experience with them will recall how long the 4 little watch batteries lasted. Seemed to me it must have been at least a season? Can't recall. (Attached is a poor quality photo of the insides.)

Could you please post the link here? I would read it I just meant the AIAA paper that is your citation #2 (and shows up I think in html form as citation #1).

A maneuver looking like a flat spin is more likely to have been a consequence of a breakup than the initiator of a breakup. Such a spin has relatively low stresses on the aircraft.

I agree Sparky. I was trying to point out how I think Rhys' scenario of the bag being out in freefall is unlikely, while the evidence is consistent with the bag coming out on impact.

As others have pretty much said, you aren't doing a low altitude BASE jump so normally there's no change in packing. And it is nice to have a canopy set up that it doesn't matter if the type of jump changes or you are late on the pull. But if one say had a hard opening canopy where one rolls the snot out of the nose (to coin an expression), then for subterminal one could avoid the rolling. Generally to speed openings, the technique would be to expose the nose more. Don't roll the nose, don't stuff back into the pack job, but keep it exposed and spread out front, maybe even with the tail not rolled around the nose, with the center cell nose well spread open to catch the air. More like a BASE or reserve pack job.

Although your post was on the wordy side, I did find the links to the AIAA flight mechanics paper to be useful. That's a nice summary of rocket energy balances and factors in flying suborbital. Some of the ideas in your post are similar to those for the bailout from orbit scenarios examined by the MOOSE project and similar ones back in the 60s. Quite a fun bunch of engineering studies. (e.g., http://www.astronautix.com/fam/rescue.htm)

I can see that at first glance, a bridle around a lines just below a freebag doesn't look good. A big issue with Rhys' scenario is that it implies that the freebag came off only at impact (since the canopy is so neatly folded) , and that the lines stayed perfectly extended and straight after impact. The bag is towed with 10+ feet of lines at 110+ mph into the ground, and ends up in that neat configuration, instead of bouncing all over? Rhys wrote: It seems harder to avoid a tangled mess if the freebag is whipped into the ground at the end of the lines, than if it were in the container. In both scenarios (freebag in or out of container before impact), you need the freebag whipped out to the end of the lines to leave them and the canopy straight. In the scenario with the bag out in freefall, whatever wraps around the bottom of the freebag have to loosen off enough that the bag could slide off the canopy, and be left with bridle rotated just 3/4 of a turn around the lines. (Or, just 1/4 turn if one excludes the bag having landed on its back.) In the scenario with the bag in the container during freefall, all the bag has to do as it flings out is rotate right , and be thrown off to the right, leaving some bridle that was ontop of it, now underneath, while the PC gets thrown off to the left, and voila: neat lines, canopy & bag land upside down, 3/4 wrap of bridle around the lines below the canopy. And as the bag hits the end of the lines, the bag's safety stow unlocks, and momentum carries even a light weight freebag off the canopy. (That's much like what happens when hand tossing a paragliding emergency parachute while on the ground, a light weight bag coming off the canopy.) I think the 'unusually neat' configuration argues for the bag coming out on impact. So is Rhys' scenario basically that the rigger packed the reserve with the bridle wrapped once around the lines? And there are the torn fibres in the cutter, which can't be a design feature, older style cutter or not.

For the student freefall rigs, they are of the style with a main ripcord, like old style US AFF. The mods are to add an FXC to the main container. Also, the ripcord handle will be in the BOC location - not sure off hand if that is an option or a custom mod. (The DZ has had other rigs since about 2003 set up that way too. Those will still be used. They were also custom modified for main AAD's, but with the design & installation done by me at the DZ when I was a staff rigger.) Anyway, it shows Aerodyne is willing to work with DZ's even for fairly unusual requests, rather than taking a take it or leave it attitude.