pchapman

Fine, but YOU can strap the crocodile in!

Some in Southern Ontario: DZ #1 dedicated ground radio instructor, out in the field with a radio & backup. DZ #2 dedicated ground radio instructor at a base station with spare radio, binocs, radio to manifest etc. But PFF instructors often carry a radio each just in case. DZ #3 (some years back) One instructor carries a radio, radios from under canopy and then on the ground. Due to staff, aircraft, or student volumes, a single channel for students is used by all.

Ok, just trying to make sense of the various threads. This one seems the best? Threads locked: Woman Guilty of Skydiving Murder Skydiving Murder in Belgium Fatality - Zwartberg, Belgium - 18 November 2006 (that was the Incident forum one - good stuff until locked because the trial is over -- although questions about the details of the actual incident remain.) Still active: Murder by Parachute Sabotage ( Recently updated but shorter) probably old but news on trial (Not updated in the past weeks) Keywords to help find this thread, many of which aren't actually here yet: Belgium, Belgian, Zwartberg, Els Clottemans, Els Van Doren. As for the actual sabotage, in the incidents forum it was reported that a rear riser got cut, and the main bridle at some place. The rear riser cut didn't apparently cause her to spiral in, but instead it whipped up and entangled with the bag, giving a bag lock. A lot of details are still hazy (to many of us) so it would be nice to see a long news report and not just the usual short ones being copied all around the world.

Loosening the chest strap can still be useful even if the slider stays at the top of the links. As the canopy swings back during the flare, a loose chest strap allows the jumper to move their body more upright for touchdown. There's less of a "about to fall over backwards" angled-back body position on landing. Some people don't care for the looser feeling, some really like it, even under a slow canopy.

I don't know what you were doing at deployment time, and I don't know much about Altitracks mounted on a wrist. But in general, errors from altitude recording devices are possible. Eg, my Protrack on the outside of a helmet always shows huge speed increases when I track off from an RW jump. I can track well and I'm certainly not doing 150+ mph downwards, but the gadget sees some sort of change in pressure due to body position change. The big speed increase disappears over time during a long sustained track. So keep checking around to see what people with Altitracks say.

I'd repack it, subject to good pull tests and making sure the jumper understood the canopy. Probably not the thing for a heavy freeflier. One can also argue about to what degree nylon degrades with age. But I don't condemn a canopy just because it won't flare as nicely as a newer design. Heck, I got a rigging 'save' on a Swift just this summer. I packed a buddies' old CRW rigs, he lent them out, and soon enough, they entangled and chopped...

Even as a newish PFF instructor here in Canada, the idea of a coach jump after a level 5 PFF or AFF seems odd. A student has to be under the care of of the appropriate instructor (eg, tandem, PFFI, Jumpmaster) until signed off for their Solo certificate. Using someone who is 'only' a Coach 1 or Coach 2 wouldn't be correct. So I am guessing that it is just a matter of terminology in this case, that the DZ or student is calling it a coaching dive because it isn't a new PFF level, rather than calling it a repeat level or whatever.

Judging the flare height based on trees, windsocks, and other objects further off might be a backup for a student whose radio is out, but one certainly wants to get away from that later. The depth perception issue comes up when dealing with flare problems. While there is a lot of technique to be learned, it is tougher for someone who for whatever reason doesn't have their depth perception and sense of movement as finely tuned to the kind of distances and speeds involved. Everyone learns from experience, but for flare heights, that can only work if one can perceive altitudes and speeds consistently. AggieDave is right. Keep working the toggles until the landing is finished. If you need to, think to yourself "fly! fly! fly!" right to that point. So many people turn off Flight Mode in their brain too early, when they haven't even touched the ground, or have just touched but have speed left. They unfortunately switch entirely to modes like Reach for the Ground or Run Like Crazy, while the arms do unhelpful things -- like not finishing the flare, lifting back up, or stabbing down on the low side. One could say that flare height on no wind days should be gauged exactly the same as on other days, by looking forward and slightly down roughly along the path one is going. (If descending near vertically, one would look up somewhat from the flight path, but that's another situation and another discussion.) Getting the flare height right, however, is a little more critical when there's no wind. One has to be able to ignore the ground whipping by quicker and not lose focus on the relationship between the altitude left and one's flare. The same goes for downwinders. I find that flaring is a matter of experience based on feedback between what one does with the brakes and what one sees and feels, taking into account past flares. So a sample train of thought might be, "...height looks right compared to previous good landings, hands are coming down, no that's not changing the flight path enough, move hands faster, OK, I can see I'm planing out, feeling the speed dropping, feeling the upwards acceleration and swing forward. Now leave hands where they are for a moment, not dropping too fast now, but still 2 ft to go vertically, a bit high, sinking at a moderate speed, keep that going as I'm running out of energy and need to get the altitude down to almost nothing within a couple seconds, OK, the ground is close now, move hands down more, fully planed out now at 6 inches, keep flying - don't forget the arms, finish the flare completely, arms are coming all the way down, dropping feet are down for a slight skid, slowing down, finish running it out, stop, drop the canopy..." Don't know if that can help anyone, but I wonder if novices sometimes aren't sure what they should be thinking of during the flare.

With the issues you found, it is pretty easy to say to send it to the factory and see what they can do with redoing it all... The bit about the zig zags is interesting. The bulletin can be read two ways. It mentions a bartacker, and a stitch pattern. Then it says, "Alternatively..." and says that an equivalent stitch pattern is acceptable, as long as it has a center stop and start. One interpretation is that it always must be bartacked, but one can have certain variations in the machine and stitch pattern used. The other interpretation is that the "alternatively" relates even to the bartacker, that one can use a zig zag stitch -- as long as one sets things up to mimic a bartack with center start & stop to avoid ravelling. For many things that's an acceptable replacement for a true bartack. I'll let the experts decide on that though. In any case, what you found goes well beyond that discussion. (Like zig zags going above the seam stitching into the rest of the cell!)

FWIW, for the King Air accident at Pitt Meadows, BC that PhreeZone referenced, the original incident thread was http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3287168

It is true that the canopy flares the same in a steady upwind vs. downwind. But it is also quite reasonable to worry about one's flare & flare height when going downwind -- because it can become a lot more critical to get it right, to efficiently plane out right down low so one can slide it out.

The suspense is killing me.

Just musing: That brings up new issues in the argument riggers have about having to pack things according to the manufacturer's manual. While using the original manual makes sense here, in the FAA's eyes does no manufacturer's instructions available equal 'grounded' or equal 'pack any way you like'?

Lots of good skydivers, some well organized DZ's, and a pretty good number of turbines. But: Mandatory AAD's at all but a couple smaller Quebec DZ's. So I avoid the place as much as possible.

Really? Or just when going beyond the optimum span, and not doing something like holding slider area constant (narrowing it front to back at the same time). Which is sort of saying that it is true only when it is true. FX's seem to have had their slider sized changed at least twice. For example, for the FX88 Kirk Smith noted in '08 that the factory slider is 58cm by 73 cm, or about 23" by 29". I saw an earlier FX88 slider that was 21.5" by 26.5" . And an even earlier FX88 slider that was 20.5" by 25.5". (These latter two pairs of dimensions are along the edges, a logical way to measure, even if I've seen measurements along the center to be the official one. Add an inch or so for centerline measurements.) I can't be sure whether the sliders were original, but it suggests there were changes in the early years of the FX. A wider slider does help with stowing the slider, but presumably the increases in width were not making the canopy open harder and harder. Maybe now the limit has been reached, and it makes sense to add more to the chord or dome it if trying to slow the opening even more.

This is an old topic I suppose, but there are still insurance forms around that ask the most inane questions about skydiving, based on understanding of the sport from something like 1960. A financial advisor and I recently filled one out. Some questions were reasonable, about licence level, when I got licenced, and how many jumps per year. Other questions got weird. Did I participate in delayed openings? Yes, most of us don't just do hop and pops. Amazingly, some airshow jumpers figured out how to fall stable in the 1930's, and in something like 1958 the word was being spread around North America about French stable freefall techniques. So I don't have to do any of those 'dangerous' freefall jumps where one counts to 3, hand on ripcord, as the world spins by blue/green/blue/green. Did I perform baton passes, stunts, or aerobatics? Aerobatics? While not quite clear what that is, I had to say yes, that's a part of normal skydiving. Everyone does it from the time they do their first back loop. Baton passes? This isn't 1960. But in my case, yes, I did baton passes in balloon suits, using round canopies, just two years ago. Do I belong to a club? I just answered yes, instead of trying to explain that there are few clubs, but there are national sporting organizations and organized DZ's these days. Where did I jump, and over what terrain? Do they rate people differently if you jump in the Alps, or subdivisions are encroaching on the airport?

No kidding, when the news reports a propeller in a pit down below. Probably worth burning the thing!

And it was all part of the big "Ground Zero" project! 1999: Awesome name. 2001: Oops. Down the drain for that branding & marketing plan. Not Precision's fault of course. (Ask Rhys though, he has some ideas about whose fault it was. )

Funny, to me the Reflex is the best looking part of the deal. Sure they have a couple little things to watch for, and are getting older, but are still well respected around my area at least. Everyone has their own opinion.

Stratostar is right. An emergency or intentional cutaway is still needed for Strongs. http://www.strongparachutes.com/Documents/PDF_Files/Tandemprerequisites.pdf

No longer required in the last couple years. Not sure exactly when it changed.

1. I wonder how many Mantas with ZP are out there from back then. Probably not many. The ad doesn't even say when anything was built, just when the owner bought it. (New, used??) But maybe it does have the ZP. Anyone packing it should know the difference. 2. ZP or not, I'd imagine a newer canopy design, like a Navigator, would be nicer to land. (And I'm saying that as someone who doesn't mind jumping F-111.) 3. If the Raven III -M was built in approx. 1996 to April 1999, it should have the bartack bulletin done. Even with added stitching, some regard the canopies built outside that date range to be better, due to the type I attachment tapes. "Ask your rigger." The seller should be telling you about exactly when the Raven -M was built.

FWIW, I use the FlashGot add on with Firefox. It is regularly updated so it is only occasionally that some site plays video using a method that it can't capture. A button appears when there's video that it can capture. It can also be used to grab a bunch of photos linked from a web page, etc. For really tough stuff, I use HiDownload, that intercepts streaming media, but that's paid software.

Great history lesson Lee! BillVon has a good point with: I agree that the mattress effect is overrated. There is some effect in having a partially closed nose or airlocks to prevent air escaping too easily, and avoiding too much 'breathing' of the canopy. And speed does make the canopy more solid. But in the end, it is mainly angle of attack that will determine whether the nose folds under or not. Lee's example of front risering the Conquest really shows the effect. Depending on the nose design, one can get the area of highest pressure around the stagnation point wandering off of the inlet, bulging in some of the shaped nose (and thus equalizing pressure again in that area, between inside and outside). But if that highest pressure area goes too far, one can get too much nose distortion or the whole nose folding under. It is hard to get enough anecdotal evidence to figure out what is really happening. Parachutes are messy to analyze because of the interaction of the canopy and the payload, the jumper down below. Speed up or slow down and the drag and weight of the jumper will affect to what degree the canopy pitches up or down, trimming to a different angle, with some angle of attack changes happening too. Say that it is correct that if one decreases the load on a canopy, it will fly at a lower angle of attack. (As Alberto has suggested.) For an aircraft flying level at a given speed that of course is true, but as I said it gets messier to prove for a parachute. A low angle of attack might not exist if the canopy was trimmed to match that light wing loading in the first place -- but it might if the canopy is flying at a much lighter loading than designed for, or tested & tweaked. The effect of a lower angle of attack might then not really be noticeable unless the canopy has small nose openings. If someone is on a lightly loaded, partially closed nose canopy, and does a sudden one sided front riser pull (at altitude), it should be easier to unload the nose and get the feeling that it about to fold, that one better not pull down as fast / far / hard. That tests the issue in this whole thread. If a lightly loaded canopy with a partially closed nose is more susceptible to jumper induced nose collapse, then it is probably also more susceptible to turbulence. So if someone could do some front riser turn tests with a Crossfire at under 1.4 WL that would be great... The natural angle of attack won't be the only factor though. As the canopy flies slower, any given turbulence, if hit suddenly, will change the canopy's angle of attack more if the canopy is slow, than if the canopy is fast. (That's not the effect of all turbulence though, as for some turbulence, it will be better to get into it slowly to let the canopy adjust to the conditions. So the exact nature of the turbulence also affects to what degree faster or slower is better.)

It was brought to my attention that the Vigil II manual now states: Do not open the door of the plane during the flight in the activation zone to avoid a possible pressure variation, which could result in an unexpected activation. There was no fanfare about this change that I'm aware of. This is in the current manual that was published some time in June 2010, v II.0.3. Earlier versions didn't have that. (At least not II.0.1 which had been around a while -- I guess the "II" refers to the Vigil II, not revision 2, so this new manual is in essence v 0.3) The "activation zone" would I suppose be at least the range from 150 ft (arming) to 840 ft + 260 ft = 1100 ft to include the belly vs. non-belly pressure adjustment. In Student mode, 1040+260= 1300 ft max. If Tandems are on board, no door open until 2040 + 260 = 2300 ft max. Technically this new rule could prohibit, say, sliding open an Otter door after seat belts are off when students or tandems are on board. In practice though, I figure it is more a precaution for C-182's and the like, with a smaller cabin volume and doors that can go from well-sealed to popped open very quickly. Perhaps 'cracking' the door open for a moment while holding the handle might be better than just letting the door fly right up. For intentional door openings, the altitude range is of most concern if there's a tandem on board, and one were thinking of throwing a wind drift indicator or dropping a hop & pop. For unintentional door openings, there are obviously still concerns about rare but not impossible AAD firings.