Divalent

Unfortunately that is not possible. Just like it is not possile to have zero doubts that the guy driving towards you in the opposite lane isn't going to veer into your lane and cause a headon as you drive down the highway. All you can do is evaluate the statistical likelihood and either accept the risk or not. I've never heard of an AFF student falling out of their gear. For that matter, I've never heard of any skydiver falling out of gear that was otherwise properly secured (chest strap on, legs in the the leg straps). The risk must certainly be vastly less than 1 in 10 million. For this particular scenario, I'd venture the risk is less than the risk you took just driving to the DZ. There are things to "worry" about in skydiving, but on the scale of things, IMO this one is pretty near the bottom of things I could conceive of.

you obviously did not RTFM (or you didnt understand it). Hint : Page 18 from Cypres2 manual Well, I think pchapman responded on point to this. I'll just note that the general recommendation to recycle and put in an offset at the take-off point whenever the elevations differ has to have some practical limits which take into account the magnitude and direction of the difference, the reasons for doing it, and the effort to do so. A 20 ft difference either direction I don't think anyone would worry about. A 130 ft higher airport (as we have at the Farm) looks like it gives you two acceptable choices: you can either recycle and offset, or accept that the trigger altitude is raised by ~130 ft. But 130 ft in the lower direction, you might want to recycle and offset (unless your are comfortable with a 620 ft trigger altitude).

It wouldn't be *wrong*. It just means that your AAD is likely set to fire 130 ft (~40 meters) higher than one might have expected if you assumed the AAD was referencing DZ level. It is not a large difference, and as I said, given the presences of some hills nearby that are close to that elevation, it might even be desirable. The main point is, I think, that jumpers should be aware of this and (if they don't recycle at the airport and set a negative offset) plan their jump and behavior around this higher trigger level.

@sparky As I said, I did RTFM and I do understand how one would do that. But that was not my question. Rather, my question was an attempt to find out what the Cypres would do in that situation. Would it adjust to the airport level? Or, given the amount of time spent at the airport, would it keep its ground reference at DZ level? (Or would it be somewhere in between?) That specific information is not in the manual, and would depend a lot on the specific algorithm used to track changes in ambient atmospheric pressure relative to the algorithm used to detect airplane takeoff. @piisfish They recommended that I set an offset at the airport if I wanted the trigger level to be based on DZ altitude. They also said that if I didn't mind a ~130 ft offset, then I could just do nothing. I'll note that I have never observed another jumper cycling their AAD and setting an offset at the airport, so I'd wager that virtually every Farm jumper effectively has a ~130 ft offset on their AAD for loads originating at the airport.

I put the question to Airtec (mfg of the Cypres) and they indicated that my Cypres likely would adjust its ground reference to that of the airport under the scenario I gave. In effect, then, my Cypres effectively has a ~130ft offset (~40 meters) upward anytime we depart from the airport. (I.e., it's trigger altitude would effectively be 750+130 = 870 ft above the LZ.) For me, I actually would prefer this, as there are some hills near the Farm (completely forested!) that are ~100 to 140 ft higher than the LZ. So given that the offset 1) is not very big and 2) it is in an arguably beneficial direction (particularly with respect to the surrounding terrain), it is something I am comfortable living with. Presumably other brands of AAD would do a similar adjustment, although it would depend on their algorithm for tracking ambient pressure.

But the issue is this: the Cypres does adjust it's ground reference pressure to account for changes in atmospheric pressure (so that, for example, if a high pressure front moved it and changed local barometric pressure at the DZ, it will adjust to that change). So my question is whether or not the 5-10 (or 15, if delayed) min at the airport 130 higher would result in the AAD instead thinking that the local barometric pressure had changed (rather than the altitude).

A question about how AAD adjust their ground reference (all brands, really, but I have a Cypress): The Farm DZ (LZ, manifest, hanger, packing area, beer refrig, etc) is located about 130 ft below the airport runway elevation. (IOW, the unit is turned on, and almost all non-jumping time is spent, at the DZ). The drive over is about 4 miles, pretty much flat until we ascend a hill (over the course of 60 sec or so) and arrive at the airport. Once there, time on the ground before lift off might range from 5 to 10 minutes. Would a Cypres reset it's ground reference elevation to that of the airport? How about other AAD brands? (Yes, I did RTFM, but it only spoke generally about making adjustments during the day to account for weather changes. I'm hoping someone might have a bit more specific knowledge about how it adjusts and whether the time spend at the airport would cause it to adjust it's ground reference upward.)

Yeah, I'd like to know, too! (I just put my rig on and no way could I reach my BOC hackey with my left hand. - I could use my left arm to move my right arm sorta in position to grab it, but I don't know what sort of pull/throw a dislocated shoulder would allow.)

So do they swoop at the exact same time (like, synchronized swooping)?

I'd be less concerned about the second hand smoke in the LZ than the presence of something burning. IMO, it shouldn't be allowed where jumpers have to be (packing area, LZ, near manifest counter, in the plane, and indoor areas).

Have you run across this guy's story? More extreme than you, but a similar strategy of setting a goal. http://www.youtube.com/watch?v=3Z-RhMvR1OA

The UGa group was out at the Farm some time last spring (and a few other times in the prior year) so they were at least active as of that time. Skydive Monroe is closer, so I think they normally jump there. (They came to the Farm to practice exiting from an Otter in preparation for an upcoming competition: SDM only has a King Air).

I had one made by my rigger recently. I'm not sure of my terminology, but it was made out of webbing material like that of a bridle but narrower: about 1 cm (1/2 inch) wide (similar to the size of the material that provides the stop to my kill line). They cut a longer piece and then formed loops at each end by folding the ends back and sewing them to the main body of the extension. One loop was bigger so that you could do a larks head attachment going over the D-bag. (the smaller looped end was attached first to the canopy). The larks heads make you lose almost an inch of length: I think mine was about 8 inches long uninstalled and adds about 6 inches installed.

European or African? How do you know so much about swallows? Jeez, I didn't expect the Spanish Inquisition... Nobody expects the Spanish Inquisition!

Although I don't mean to diminish Tink's achievement, is that so unusual? What is the industry average for chops? A general figure I hear bandied about is one cutaway per ~700 jumps on average. If tandem rigs are similar and they are random, you'd expect almost 25% of TI's to make to 1000 jumps without one. (It drops to about 14% if the rate is 1 in 500; or about one out of about every 7 TIs would achieve that distinction).

Thoughts/ideas based on your description (particularly since it records 10 minutes continually under descent, which suggests it is something to do with the shutter button): - does it only shut off when you are in high wind? (climbout/freefall, or sometimes when in plane?) - does it work properly if you use someone elses housing? (I.e, is the a faulty/flaky shutter button on your camera, or a faulty/flaky housing shutter activator?) - can you get it to stay on if you put it in "one Button" mode? In this mode, the shutter button is disabled: it starts recording when you power it up with the power button. If the shutter button (either of camera, or the housing) is flaky, this mode should allow you to get the video you want. (I just RTFM, as I just bought one )

You are asking for simple answers to non-simple questions (in this thread and others). You might want to review your HS (or college?) physics. You really would have a better understanding if you worked it out yourself. Here's a good place to start: http://en.wikipedia.org/wiki/Free_fall

clicky

your second link made my virus/malware software explode.

Yeah, its boring as fuck. But this sport attracts people like the character Dunbar in the novel Catch 22, who figured out that time passes slowly when you are bored. So you end up living a seemingly longer life if you actively seek out boring pasttimes. And for the boredom factor, what can beat skydiving? Come join us and you can live long too!

The concept is illustrated here very nicely: http://www.youtube.com/watch?v=R2a8TRSgzZY

0ft/sec x 7 sec = 0 ft: all the watermelons land on each other. I must be missing something here, because he clearly was advocating using ground speed to determine exit separation (the "7 sec" was his example), which is the right way to do it, yes? [by that I mean, of course, you have to rearrange the equation to be: X = Z / Y Where X is exit interval time in secs, Z is desired separation distance in ft, and Y is the ground speed of the plane in ft/sec]

He gave the answer in his question: ground speed (in ft/sec) times 7 seconds.

Visit their web site and see what information is available there. When was about to visit Z-hills, I was able to download their waiver form and fill it out in advance. Also, they used to have a really good DZ Overview for licensed skydivers that gave a lot of good general information (jump run directions, landing areas, policies, etc). It was about a 5 page PDF (in color, with photos, etc). But I just went to their website and I can't find it there anymore. I thought it was an excellent starting point, which complimented the orientation I got when I arrived. (It struck me as a good model for other DZ's to copy).

Yes I do that (rolling them outward). Probably because I saw it in the same video, and don't like hard openings, and thought it would prevent them all getting inflated in one instant. I don't really know if it makes a difference, but I do it just to keep things consistant. (I try to pack the same every time). I think it might add just a bit to the snivel, but in my limited experience, the ones where I had a noticably longer snivel the cells were (mostly) inflated, but the slider was just staying up. So I don't think it would have a major impact. But if you want to experiment with it, I'd be interested if you find a difference. I noticed the same thing, although for some reason it seems to be happening less frequently. (Maybe the d-bag extension helped?) Anyway, I try to be a careful and diligent packer, and the main reason I like this method is the ability to reopen things up and look at your lines and slider after you flop it down to confirm everything is where it is supposed to be. And then the steps you do after that (fold and roll) are very unlikely to disturb things. Although I haven't done it very long (~100 jumps), the worst I have was one "brisk" opening. (where afterwards I said to myself "that seemed kinda harder than usual" but nothing that would keep me from continuing to jump even if they were all like that.)