brettski74

Perhaps you should express that opinion to the APF and suggest changes to the APF Sporting Code. I'm not sure when the 75% rule was added or what the most recent edits actually were. The most current version is from 2009. I was under the impression that there were non-Aussies on the previous 81-way record, so maybe the 75% rule was an old rule from when records had to be completed within Oz and the most recent changes to the rules for national records simply added the rule stating that they may be done anywhere in the world but didn't change any of the other rules, but I'm just guessing. I'm not sure who would have access to historical version of the APF Sporting Code. The current version is available online. I would have liked to have seen a totally Aussie formation - it would have given some more legitimacy to the result given that it wasn't being done in Australia, but what was done was legal within the current sporting code and also the largest formation likely to be done with the group and planes available.

Mostly correct. No acceleration is impossible, but the device is designed to save skydivers in freefall, which means that they are accelerating under the influence of Earth's gravity alone, so it should give some consideration to what is possible under such circumstances. Almost correct, but again missing some of the details. It is impossible for a skydiver can accelerate from under canopy with a specific range of descent rates to a descent rate exceeding 35 m/s in less than 5/8 of a second. This is a fairly well accepted law according to Newtonian physics. For the record, 50mph is about 22.2 m/s. Under the influence of Earth's gravity only and ignoring drag, it would take about 1.3 seconds to reach a descent rate of 35 m/s. In the real world, it would take longer than that. For you to accelerate to a descent rate of 35 m/s with no drag in a time of 0.625 seconds, your initial descent rate would need to be about 28.9 m/s, which is around 65mph. Again, these calculations ignore the effects of drag, so in the real world, your initial descent rate would have to be higher than this. There's no reason why the device can't have the benefit of the pressure and other derived data while you're under your high speed malfunction and plummeting to the earth at around 50mph. If you look at the graphs downloaded from the devices that misfired, they actually show consistently negative descent rates from about -7 seconds to -3.5 seconds as well as descent rates at or close to zero for another 2 seconds after that and prior to the beginning of the pressure spike. This suggests to me that the device is still making pressure measurements and altitude/descent rate calculations prior to detecting freefall and that in the event of an activation, it is logged somewhere therefore it must have been available to the device at the time of activation also. Now, you could say that due to pressure variations induced by body position, we can't be sure that the descent rate of 50mph is accurate or calculated based on pressure changes from other causes. We can say, however, that virtually all skydives start from aircraft that are in relatively stable flight and therefore at descent rates at or close to zero. This being the case, there is no need for the device to detect that I'm in freefall in such a short space of time as 0.625 seconds as there is no way I can reach the activation speed in anything close to this time under the influence of Earth's gravity alone. The only plausible exceptions to this stable flight assumption that I can think of are stunts or aircraft emergencies, however, I'm not sure that I'd want an AAD firing while I'm in or attached to an aircraft in a nosedive, anyway.

I'm not suggesting that this is what is happening. I'm not talking about the decision to activate. I think that might be where the confusion comes from. To reference the incident that prompted all of this, the device was in an aircraft that was not descending - it registered a zero descent rate just prior to the pressure spike. In Vigil's responses they mention that the device detected the freefall in 0.625 (5/8) seconds. The firing parameters of the device in Pro mode require a descent rate of 35 m/s and an altitude between 840' and 150' (body position corrections notwithstanding). From a a descent rate of zero, it will take over 3.5 seconds under gravitational acceleration alone to reach 35 m/s descent rate - and that's assuming no drag. Once you add in drag, it will take even longer. Even if you consider the lower activation descent rate for Student mode of 20 m/s, that's still going to take over 2 seconds with no drag and even more with drag. I simple don't see the necessity to detect freefall in only 0.625 seconds. The bigger picture from all of this is that the device should have some idea of what is realistically possible in freefall and be able to rule out impossible situations to prevent misfires at inopportune times - particularly when inside an aircraft. I will grant that determining this based on barometric pressure readings alone may not be as simple as I may have initially made it out to be, but a device that can think at one moment that it's at or near zero descent rate and less than a second later decide that it's in freefall at a descent rate in excess of 35 m/s doesn't make a whole lot of sense either.

In all of these situations, the jumper exited the aircraft, so why is the device not capable of logging measurements from that point? If you have a canopy collision at 500 feet, it's a fairly safe bet that at some point prior to that, you exited an aircraft. There is no reason why the device cannot be logging data during this descent, so I don't understand how we don't have the benefit of more than 3 seconds of data. That aside, it's also extremely unlikely that an AAD would save you in such a situation. Under my canopy, I descend at about 8 metres per second. With no drag, it would take about 2.7 seconds under gravitational acceleration to reach the speed needed to fire. In that time, I would have fallen about 200 feet. In the real world, there will be considerable drag, so the acceleration will be reduced which in turn increases both the time and distance you will fall before reaching firing speeds. If you strike the tail on exit, I'm guessing that you're at full altitude, so why is there a need to deploy the parachute in less than 3 seconds from the exit? The firing parameters won't be met until the skydiver is at a lower altitude, so it's going to take somewhere in the vicinity of 50 seconds or more for that to happen. Even if this is some kind of accidental exit while climbing through 1000' or less, it's still going to take more than 3 seconds for the falling skydiver to reach the activation speed of the AAD. Wingsuiting... There will still be a long trend of descent data for something like 2 minutes or more before the wingsuiter reaches an altitude that meets the firing parameters. At what altitude does the wingsuiter throw their pilot chute? If we're talking about a "normal" deployment altitude with a malfunction happening, then we're above 2000' to start with and it will take well over 5 seconds to descend from deployment altitude to the 840' activation altitude. If this is a low pull, how low is your descent rate? 40mph? That's a little under 18 metres per second. With drag, it's going to take more than 2 seconds to accelerate to the activation speed of 35 metres per second. This is also assuming that the descent rate has been so slow that Vigil didn't think you were in freefall yet. The Vigil manual doesn't seem to have any details about what conditions need to be met for it to decide you're in freefall. 2 seconds is still much more than the 5/8 of a second that Vigil takes to decide that it's in freefall and should activate. They make a big deal about this in their literature as though it's a good thing, but I can't think of a single scenario where it's necessary to makes such a fast decision.

Not lots of assumptions. Just one assumption that the device is being used to skydive on Earth, in which case we have a very good idea of what is possible under gravitational acceleration from Earth's gravity. I think that's a fairly safe assumption. All of these involve a skydiver falling under gravitational acceleration due to Earth's gravity, so my previous statements still apply. The only scenarios to which my previous statements do not apply are those where the skydiver is being accelerated toward the ground by something other than gravity, such as perhaps rockets, a plane in a nosedive or perhaps even something like a microburst, but I cannot think of any such scenarios where a reserve canopy deployment makes a lot of sense without more information that is not available to the AAD firmware. This is pretty much exactly what I'm saying, although I think you're talking about the maximum rate of change in barometric pressure. We know what the maximum rate of change of velocity of pretty much anything in freefall thanks to a guy called Sir Isaac Newton. Pressure measurement issues due to body position and burbles could very well mean that we need to allow for larger short term variances in the measured pressure. The longer term trend should still be consistent altitude changes under gravitational acceleration. What is the purpose of this pause? You've determined that something extraordinary is going on, but despite the designers having no understanding of what this scenario is nor designing the device to handle it, you're just going to wait a second and then go ahead and fire anyway? AADs are designed to solve a fairly specific issue. They are not designed to solve all kinds of weird and wonderful situations. If the device identifies that something is going on that it's programming was not designed to deal with, it should keep quiet and let the human make the decisions.

It's no different. Vigil doesn't know that you've cut away. Vigil only knows about atmospheric pressure readings from which it deduces altitude and from there, the vertical component of your velocity. It's not limited to only making the decision to fire based on the data from when you cut away. It has the benefit of all the data from the time you left the plane - much more than 3 seconds. The purpose of the device is to save a skydiver in freefall in a low-pull/no-pull situation. It does so by deploying your reserve canopy. If the device deduces vertical acceleration that exceeds gravitational acceleration by a significant margin, then the pressure variations that it's seeing are clearly not due to freefall which means this is a situation that the device and/or reserve canopy was not designed to handle. Firing in such a situation is not a good idea as you have no idea what the situation is or what the outcome of attempting reserve deployment might be. Better to leave that decision to the skydiver who has significantly more information about what's going on. We generally all leave from aircraft in relatively level flight, where the vertical component of our velocity is zero or very close to it. Freefall speeds capable of meeting the firing parameters simply do not happen when exiting from level flight in the short timeframes that Vigil's press releases imply are important. If you want to make the decision to fire based on 5/8 of second worth of data, that's fine, but it's not as important as the statement appears to make it to be. Don't get me wrong. I'm not simply trying to bash Vigil. I have a Vigil 2 in my own rig. I'd like to see a better product.

On the positive side, I'm glad that Vigil have posted this statement and it does address some of the issues raised. It's also re-assuring to know that they are working to figure out the conditions that caused the issue and hopefully address it. I understand the point about activation altitude and flight level restrictions - interesting point. I don't really have a problem with the activation altitude, nor do I think that it's really a solution to anything to increase it. I also think that this could be an advantage - albeit a minor one over other designs. On the down side, I see a lot of technical detail mentioned in a way to suggest that the Vigil design is superior, but I'm not sure that it is. You talk about detecting freefall in 5/8 of a second and therein lies the problem. Yes - Vigil has has had saves, but can you identify any of those where deciding that it was in freefall in 5/8 of second would have made any difference over whether it took 3 seconds to make that decision? From stable flight (0 m/s vertical speed) and with the unit in Pro mode, it would take about 3.5 seconds to reach activation velocity under gravitational acceleration and assuming no drag. In practice, it will take longer than this due to drag. With this in mind, I find it difficult to see why it's so important to decide that we're suddenly in freefall and act in 5/8 of a second. Based on my understanding of them, I do believe that Vigil's firing parameters are too simple. For a typical low-pull/no-pull scenario, the skydiver will have been in freefall for much longer than 3 seconds, so again, I don't see why it's advantageous to decide that we're suddenly in freefall and activate so quickly. Finally, from what I understand of the Vigil firing parameters, I still believe that they are too simple. As far as I understand, it's really only considering the altitude and the rate of change of altitude (vertical speed). I think that at the very least, it should also be considering second differences (ie. rate of change of vertical speed) to rule out situations which could not be possible under gravitational acceleration and if such a situation is detected, it is probably safer to do nothing than to just wildly activate because it thinks we're suddenly in freefall. Freefall just doesn't happen that suddenly.

I've also been responded to privately regarding the recent Vigil misfires. It seems that more is going on than just "The device worked as designed.", although I'm not exactly sure what, yet. I did suggest to them that it would do a lot more to help their image to come out in public and say something to that effect - even if the current statement is just that they're working on the problem. I also tire of their statements like "Vigil is acting also faster than other AADs." This is a spurious statement. I presume they're stating this because they think it makes Vigil sound superior to other devices, however, there's no statistical or other data I've seen to back up the premise that operating faster than CYPRES, Argus, Astra, etc produces better or more consistent results in accordance with a typical user's requirements. Given that Vigil seems to have developed a reputation for being trigger happy, whether well deserved or not, telling everyone that it fires off your reserve faster than anyone else would seem to me to be a bad marketing move just reinforcing that reputation, but maybe that's just me.

I'm assuming that you do that because you can't track very well. A good tracker will end up above and far ahead of the rest, so the bad trackers will be below and behind them. Tracking on your belly would make it easy to see them. Back tracking would only be good to watch for everyone else if you can't track very well.

It's funny you should ask that. I'm on an event right now where several have been cut and sent to do remedial tracking jumps because of insufficient tracking skills. That said, this is the first time I've seen that, but it's a start. Also, we're not in Europe right now, nor is this a European event.

It seems that as fast as we post the links they keep getting removed or made private. That link I posted has been removed already.

Not sure if this is the same video, but based on the discussion, the following link seems to work and seems to fit the description above... http://www.youtube.com/watch?v=yy8BIQcxdBg From the ground video at the start: Methinks that everyone knew what was in store for this jump.

Who said that? This would be just as ignorant an attitude to take as your suggestion that there's something wrong with asking for a pin check. This is the bit I'm concerned about. There is nothing wrong with asking for a pin check. You would be right in that you should know your own gear and you should check your gear thoroughly every time before you gear up for a load, but to suggest that there's something wrong with asking for a pin check or that asking for one imply's that you don't know your gear is just silly.

I don't have any advice on where to stay, however, just thought I'd let you know that you've picked dates that coincide with the Australian large formation record event. The event has about 120 or so people descending on the Perris area for two weeks and has had the IHOP and bunkhouse reserved for about a year, now, as well as several local houses and probably a few hotel or motel rooms. I would expect that accommodation will be a little tighter than usual, whatever that is... some might say that having a large formation event at Perris is the definition of usual... If you can squeeze in a tent, camping is always free. I've also known people in the past who've rented an RV for a week or two, although that can get expensive unless you've got people to share the cost with. You can also sleep in a car. Try to rent yourself a Dodge Caliber. They are shit to drive, but fairly cheap to rent and the back seats fold down flat which makes for a half-decent bed provided that you have a good, warm sleeping bag. Thrifty always seems to have a good supply of Dodge Calibers. Other than that, I suspect that you'll be looking at off-DZ accommodations.

Great! I never suggested that you didn't. I was faulting your analogy. With invisible elephants, you're suggesting a problem which doesn't exist and with screaming yooyoo, you're suggesting a solution which presumably has no real effect and then go on to draw the obviously false conclusion that you avoided the invisible elephant because of such action. Unlike the invisible elephants, problems which can be detected by visual inspection of the rig do exist, and having such a visual inspection prior to jumping can allow the problem to be either corrected, or failing that, at least mitigated by not jumping. Therefore, as I stated earlier, your analogy is flawed. You need to go back and read my posts in context. They were all replies to specific posts suggesting that there was something wrong with asking for a pin check because as a licensed skydiver, you should know how to check your own gear. I strongly disagree with this sentiment and feel that this sends the wrong message to student and novice skydivers. While you didn't say that, you did question my position. I have no intention of attempting to force you to do anything.

I think the opposite is more likely to be true. Compare the equipment we have today with that of 30-40 years ago. If anything, I believe that the gear, knowledge and training that we have today makes the sport much safer than it was in the 1970s and as a result of this, there are many more people willing to try the sport than in the 1970s. I don't really know of any skydivers that are in the sport for the danger or the risk of injury/death. Most skydivers I know are in the sport because they like the feeling of human flight, the challenge of learning new skills and/or sharing that experience with others.

You're analogy is flawed. You're suggesting that potential problems with pin, bridle and pilot chute don't exist and that even if they did, a visual inspection by someone would not provide any means to address them. While such problems may be rare compared to the number of jumps made without issue, there are stories of problems with pin, bridle or pilot chute that are visually apparent. There are also incidents of fatalities and injuries caused by pilot chute in tow or premature deployment. Give me a break! I'll give you that my closing sentence may have been melodramatic. I don't have a problem if he wants to do all his own checks on his gear. I don't think it wise, but that's his decision. What I take issue with is the suggestion that real skydivers don't need pin checks and the implication that asking for a pin check is tantamount to admitting ignorance of your own gear.

Other people have thought the same thing and been wrong. As I said before, you're never too good to not request a pin check. Despite your best efforts, things can happen on the ride to altitude that you may not be aware of. For your sake, I just hope that should anything like that happen to you, it doesn't kill you.

Really? Why not Hammer? (ie. block 13).

Who here said that it's ok not to know how your rig should be? You seem to be equating the request for a pin check with an admission of ignorance of your gear. I check my rig before I put it on, but I still request a pin check prior to exit. I also agree with popsjumper on having my gear checked by someone I trust, but I still request pin checks from such people. It really seems to me like more of an ego thing. I see it often. People get off student status and start to think that they know what they're doing now. They don't need help. They can handle this all themselves. Thinking like that has killed a few people. You say you don't like people messing around with your rig because it's "different", yet you mentioned that you get asked often about it and you don't mind telling people, so what is stopping you from explaining or showing your skydiving friends your rig and what to look for and having them give you a pin check? If the people next to in the plane are not one of your friends familiar with your rig, what is stopping you from telling someone in the plane what to look for before they check your pin? I'm picky about who checks my pin on my CRW gear, because many of skydivers have never done CRW and freak out when they see some of the shit hanging off of a typical CRW rig. When I'm doing CRW, there will be at least one other CRW jumper next to me on the plane, however, so we check each other's pin. problem solved. While I can accept the desire to have someone you trust check your pin, this is hardly an insurmountable problem. I'm not following why you think it is.

That's a fantastic attitude. Remind me never to jump with you. I'm sure you'll feel just great if one of those people you gave a "fake" pin check ended up injured from a malfunction of some sort.

I would say: Quite likely I would also say: Not absolutely will happen IIRC there was a female fatality in Italy many years ago where she fell out of the rig when the chest-strap failed. While some may disagree with me, I consider the chest-strap to be a structural part of the harness. There have been other threads discussing this question on here, such as this one. I haven't seen any real data. Some people think it likely. Others seem to think it possible but unlikely. Either way, I think everyone agrees that it's possible to fall out on deployment if the chest strap is not connected properly, so it's certainly worth a few seconds checking it.

I'm assuming that you're doing a pro-pack over your shoulders. If you're flat packing, I probably can't help you as I rarely, if ever, do flat packs. The best tip I can give you is to pack with the wind at your back. This helps prevent the canopy catching wind while you're flaking the fabric. Other than that, try as much as possible to keep the wind on top of the canopy. If the wind gets underneath it, it'll catch air and go all over the place. The same basic principle applies while gathering your canopy and carrying it back to the packing area, but that takes a little more practise to do well. If nothing else, I find that placing my arms across my chest with the entire canopy loosely S-folded around them makes for much easier carrying in windy conditions.

I'm curious as to how you're looking at your pin or pilot chute while you're in the plane and wearing your rig? Yes - you can feel around there with your hands, but that won't tell you everything that a visual inspection by a fellow skydiver can tell you. What is it that's stopping you from asking for assistance? I know what to look for, or if I don't, I'll ask the owner/wearer of the rig. I ask for a pin check not because I don't know what to look for. I ask for a pin check because I know that I cannot see the back and bottom of my container while I'm wearing it.

Can someone explain "flight line checks"?