Sep 24, 2012, 5:43 AM
Post #1 of 21
Sigma passenger harness
We are jumping at our dropzone with Sigma harnesses and almost all of the times we experience that after opening the chest strap of the passenger is close to the chin / throat. We think that somehow they are slipping, because we think we fit them correctly (following the guidelines of the manual).
Attached you find some pictures from a handcam video of a random jump with a sigma harness (the video is not made at our club, so used it from youtube) showing the "problem"
Picture 1 is just after exit and it seems that this guy is fit properly (chest strap there where it should together with the straps on his shoulder, against the shoulder bone)
Picture 2 is after opening you can clearly see that the straps which were against his shoulder bone in freefall are now at the height of his ears, and the chest strap is near his throat.
Does anybody have any idea what causes this and how it can be solved.
Looking forward to your replies and suggestions.
(This post was edited by Bibabarb on Sep 24, 2012, 5:43 AM)
Its because once the canopy opens, they are loading the top connection points and all the slack in the harness is pulled up..
lots of slack there. The best is to adjust the harness according to the Sigma manual. Takes some time to adjust properly a harness.. I don't care about kicking in tandems as fast as possible, I prefer to take my time and have a safe jump and bring my passengers down with me.
When you arrive at the boarding area always ask your passenger to use both his hands and bring back both leg straps, one after the other, as high as possible on there legs. If you compare the space between the top of the harness and there shoulders, before and after they moved there leg straps, you'll be surprise to find a few inches between before and after and even more with fat passengers. As an examiner I teach every TI to do so with each and every passengers. With out doing that your passengers will end up with the chest strap in the chin on opening witch is not the end of the world since you can loose it after opening but that mean your passengers will also be too low in the harness witch is a bad situation on landing because your legs wont save his back in a case of a down draft or a mistake from you. Even by doing so some times instructors have tendency to put the chest strap too high,by putting it lower your passenger will only be more comfortable and you have no chance to loosing it on opening. The back strap if not well adjusted (or completely loose) can and will have a huge affect on the passenger safety on opening.
Try it and let me know...you'll see a huge difference.
I am an Tandem Examiner for UPT and i have seen a few cases like this around. from the pics its clear that something was not adjusted correctly. my first advice would be to make sure that the legstraps are in the correct position and properly adjusted. if you leave them to loose it allows the passanger to slip on opening.after i put the harness on its the first thing i adjust and tighten. they way i check it the buckle should be correct place and you should be able to just about to slip your fingers in behind the legstrap. but of course when doing that becareful in doing that especially with a female. also the back diagonal on the pic looks not be adjusted incorrectly. depending on the aircraft you use, if they are sitting down before you hook them up i always tighten them up before hooking them up. you be suprised how much slack there is on them even if it looks ok when you put them on. also make sure that the chest strap is in teh correct position in the first place. also its important that one checks the harness before you board the plane. a quick way to check it is to try to lift the passenger up on the ground by the top attachment points. i am fairly luck that i am 6'5 tall and have plenty of strenght to do that. if you dont have the strenght put your rig on and clip on the top snaps and take the passangers weight for a few seconds, that will give you a very good idea if the harness slides up to much on opening. if it does check all the adjustments again and correct accordingly. fair play for asking, its definetley something that needs to be sorted out immediatley. as you might be aware there is a nasty video clip on youtube of a grandmother nearly falling out of her harness just after exit. the reason was because her haress was barely adjusted at all. hope you get it sorted out.
(This post was edited by irishrigger on Sep 24, 2012, 10:15 AM)
I'd like to offer some thoughts that might be helpful.
- The chest strap on the Sigma harness is not prone to sliding up or down on the main lift web as there isn't any force pulling or pushing on the main lift web friction adaptors once the instructor has properly positioned it in the fitting process.
What you are experiencing when you see a chest strap that is properly fitted on the ground that appears to have risen after opening is that when the canopy deploys and the student is pulled vertical, that their body sinks into the harness. It is an avoidable event (the appearance of the chest strap rising, and the vast majority of the sinking), provided that the instructor fits the harness properly and considers a few key points.
1) When fitting the passenger harness there is no weight on the leg straps from the body. After properly adjusting your next harness. Take each leg strap at its apex on the side of the leg, and give them a firm pull upwards (warn the student prior to doing this). You will see the leg strap travel up 1-3 inches, which simulates a majority of the weight loading on the straps when the weight of the persons body is suspended. That few inches of travel is enough to create the appearance of the chest strap sliding up on opening shock. Suspending a student in their harness on the ground is the best way to assess this and readjust as necessary. And 2) Despite the most perfectly fitted harness on the ground, even when judged from a suspended harness, the human body is both gelatinous and pliable. That means that when you put an object of the weight, composition and flexibility of the human body through a rapid deceleration from 120mph to 16ft/sec over the course of a few seconds, the body will sink into the harness a little deeper than you could duplicate on the ground.
One of the best indications of a properly fitted harness after the canopy is open, is the position of the back pad on the student while under canopy. If the student sunk so far down into the harness that the top of the backpad is at or even above their head, then the diagonal adjustments were too long.
And as always check your students harness a minimum of three times. Once after donning and fitting the harness, a second time before boarding the plane and a third time before exit.
If I can be of any further assistance, don't hesitate to shoot me an email at email@example.com.
I'm used to placing the chest strap fairly low on tandem students, lower than what one sees on a typical skydiving rig. So when the chest strap 'moves up' (relative to where it was on the person on the ground), the strap isn't too high.
While the rest of the harness obviously has to be done up properly, with tandem students there is in general more 'sinkage' in the harness than we get for experienced jumper rigs.
So it seems to be a practical thing to do, even if it does make the student feel a little less secure with the shoulder straps more easily sliding off particularly when sitting in the plane.
Note for example the new "United Parachute Technologies 2012 Assumption of Risk Waiver Video" that's on youtube (https://www.youtube.com/watch?v=tFVINO-BqCw), at around 4:50 -- the chest strap is set quite low. (It does look a little higher on the actual jump at the video's beginning, but of course that may be from a different video take, and with some tension on the shoulders, it may have shifted up a bit.)
Last I checked however, the UPT guide to harnessing students with the Sigma harness shows a more conventional higher chest strap position.
UPT fashioned an ambiguous harness adjustment guide, and somehow I doubt you're going to receive more concise info on the phone or via email. UPT instructions say "Slide the chest strap vertically into the correct position and tighten." That statement, and most of the rest of the harness adjustment guide, can be interpreted in many ways by many people. In fact if you talk to a few different Sigma I/Es you'll get different explanations about how it should be done. Different I/Es will harness the same student in different ways. What's correct? Currently that's for each new Instructor to figure out on his own through trial and error.
The real answer would be a video, produced by UPT, showing everyone how to harness a student. It would end a lot of misinterpretations, confusion, and arguments. I'd want it to be about 30 - 60 minutes. There's enough important material to fill that space. "This is what we do... this is why we do it... etc etc".
It seems to me that the explanation given by Tom just a couple of posts ago gives great pointers on how to adjust the harness
it is also true that a good video would be a nice thing to have.
I agree Tom gave some good input and worthwhile things to consider.
The harness adjustment guide has always bugged me. If there were adequate instruction provided by UPT, this thread would not exist. I wish I could tell the OP RTFM, but it's not a valid suggestion in this case.
in the US, aren'tz the TM/I's type rated ? Shouldn't they be properly trained and examined (by manufacturer approved TIE's) ? In that case I do agree that at least for the US, the thread shouldn't exist.
But as you noticed, for example, both the OP and myself are not in the US, and at least I do not have a type rating (but do jump Sigmas, Vectors, PdF Atom Tandem, Basik Tandem), which leads to learning "via the instruction manuals and other instructors", and therefore possibly have some information lost in the way...
BACKGROUND: the old (Vector II) harness was much less comfortable than the Sigma harness, both under canopy and walking around on the ground. The Sigma harness, for the majority of Students, is comfortable enough to completely fit/adjust/tighten all points of adjustment on the ground before boarding the aircraft.
For the minority of folks that find it uncomfortable, I have found that they are either 1) not of the body type that will allow ANY properly adjusted harness to be comfortable (i.e. high body fat & overall lack of musculature), or 2) they don't like the "squeeze" or restriction of a harness in general. I simply tell those people that the harness has to be adjusted this way, and that the discomfort will be worth it in the end.
It is quite common that TIs leave the upper part of the harness, specifically the main lift webs and diagonals, generally loose until the hookup process begins -- for the sake of Student "comfort." I don't teach it that way, nor do most of the Examiners I ask about it.
OVERALL ADJUSTMENT PHILOSOPHY: I am a firm believer in completely fitting/adjusting/tightening all points of adjustment before boarding the aircraft. I have had two tandem emergency exits in which I was hooked up and tightened down sufficiently to exit the aircraft in less than 30 seconds. In those situations, thankfully, and immediate exit was not required - we exited a couple of minutes later. Had an immediate exit been required, I would not have had time to finalize adjustment - completely fit/adjust/tighten - before needing to un-ass the "sinking ship."
The other reason I don't like the "loose upper cage" method is that it is difficult to adjust that part of the harness properly with the Student sitting down in front of you. Very experienced TIs can do it blindfolded, but they learned through trial and error that was unnecessary - you can see how a Student's completely adjusted harness fits when they are standing in front of you, and/or as you stand behind them and partially hang them from the upper attachment risers.
My Tandem Students board the aircraft with a completely fitted/tightened/adjusted harness. During the hook-up process, I snug down the diagonals a bit more because I find that they loosen up after initially putting the harness on the student as they walk around or sit/stand repeatedly.
THE CHEST STRAP: on men (as in the OP's example) I usually put the chest strap just below the sternum (breast bone). If the man has very broad shoulders or is generally a wide-body, it has to go a little higher than that to encourage the main lift webs to stay vertical. On the majority of women, I put it just under the breasts. On women with large, low-riding breasts, I put the chest strap directly on top of them. On both men and women, I reach around under canopy to loosen it and make the canopy flight more comfortable. I have a technique I use for women so as not to be invasive and remain professional.
RECOMMENDATION: UPT has a Student harness fitment video in the works. Mark Procos showed us a rough edit at the TME conference in April. Hopefully that video will follow now that the updated waiver video is out.That harnessing method emphasizes the lower cage to eliminate escape routes for students to fall out of the harness. Incredibly that has happened twice now, and almost happened a third time with the little old lady in CA (who stayed in the harness because she held herself there). I am also told that the FAA has told USPA in so many words that if another Student fatality occurs because someone falls out of a harness, tandem jumping in the US will cease to exist. None of us want to lose another Student this way for ANY reason.
Completely adjust the harness when you put it on the student, check it again before boarding the aircraft, and again after you have hooked up and tightened down.
"THE CHEST STRAP: on men (as in the OP's example) I usually put the chest strap just below the sternum (breast bone). If the man has very broad shoulders or is generally a wide-body, it has to go a little higher than that to encourage the main lift webs to stay vertical. On the majority of women, I put it just under the breasts. On women with large, low-riding breasts, I put the chest strap directly on top of them. On both men and women, I reach around under canopy to loosen it and make the canopy flight more comfortable. I have a technique I use for women so as not to be invasive and remain professional."
What he said. Think of it as a "sternum strap" instead of "chest strap" and the problem will disappear 90% of the time. (I'm assuming you're aware the strap slides up & down on the main lift web, right?)
lots of good information here by Slotperfect too . Thank you
I am just sick and tired of seeing misadjusted harnesses
I geared up a student for a jump with another instructor using a Strong harness. I told him that I put it on him and adjusted it the way I usually do for my harness and that he should check it to make sure its the way HE wants it.
He took a look at it and asked if it was my Sigma harness, because it fit the student so much better than the Strong ones!
Take each leg strap at its apex on the side of the leg, and give them a firm pull upwards (warn the student prior to doing this). You will see the leg strap travel up 1-3 inches, which simulates a majority of the weight loading on the straps when the weight of the persons body is suspended. That few inches of travel is enough to create the appearance of the chest strap sliding up on opening shock.
I like that, and now that I've watched the new UPT waiver video, I see the instructor doing just that.
The primary thing that I'll nit pick in someone elses harness fitting, is that they'll often have the leg straps running to horizontal, or the apex at the sides to low. This allows the student to sink down in the harness on opening, and also slide around under the TI in freefall.
I've now spent enough time on dz.com, since I can say that I've learned something.
"1) ... Take each leg strap at its apex on the side of the leg, and give them a firm pull upwards (warn the student prior to doing this). You will see the leg strap travel up 1-3 inches, which simulates a majority of the weight loading on the straps when the weight of the persons body is suspended. That few inches of travel is enough to create the appearance of the chest strap sliding up on opening shock. Suspending a student in their harness on the ground is the best way to assess this and readjust as necessary. ..."
Agreed! I have been picking up students - by their leg straps - for years. I started doing it to snug their leg straps high in their crotches, to confirm fit, but also found that it is a powerful psychological technique.
Before I dis-located my shoulder, I was often asked to take the largest students (e.g. guys in the 230 pound range). hen 190 pound ME picked them up, turned 90 degrees and set them back down (gently). I sent a powerful message that "we are going to do this skydive my way." Few of these guys had been man-handled in decades!.