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Why do we keep colliding?

 

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airdvr  (D 10977)

Jul 19, 2010, 1:21 PM
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Why do we keep colliding? Can't Post

Again this weekend 2 canopies converged on eachother and 2 more are gone.

UnsureOver and over it's preached 'keep your head on a swivel', 'it's not over until you're on the ground'Unsure


theonlyski  (D License)

Jul 19, 2010, 2:26 PM
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

In reply to:
Again this weekend 2 canopies converged on eachother and 2 more are gone.

UnsureOver and over it's preached 'keep your head on a swivel', 'it's not over until you're on the ground'Unsure

Not even over once you're on the ground. Pirate


Inspired  (B 35971)

Jul 19, 2010, 2:39 PM
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

In reply to:
Again this weekend 2 canopies converged on eachother and 2 more are gone.

UnsureOver and over it's preached 'keep your head on a swivel', 'it's not over until you're on the ground'Unsure

I just recently had it pointed out to me that I was flying in another jumper's blind spot. Not a safe place to be.

Lesson learned: It's not just about me knowing where they are. It's also about making sure they know where I am.


Premier NWFlyer  (D License)

Jul 19, 2010, 2:45 PM
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Re: [theonlyski] Why do we keep colliding? [In reply to] Can't Post

In reply to:
In reply to:
Again this weekend 2 canopies converged on eachother and 2 more are gone.

UnsureOver and over it's preached 'keep your head on a swivel', 'it's not over until you're on the ground'Unsure

Not even over once you're on the ground. Pirate

True dat. Saw a knee of a landing jumper hit the head of an already-landed jumper recently. I believe both of them ended up with minor injuries, but it could have been much worse.

Why do we collide? All kinds of reasons. People who focus only on their own pattern and not where they are in relation to everyone else. People who believe they have the "right" to land where they want/how they want on every jump, no matter what anyone else is doing. People who think they have their head on a swivel but get myopic once they're in the pattern.

I try to create separation as much as possible, both vertical and horizontal. When I find myself near another canopy, communication becomes very important. Kicking your legs to say "I see you" is a good start. Eye contact also helps. If you happen to be on parallel final approaches, keep up eye contact with regular glances to make sure you see them and they see you (and they see that you see them) and that your paths continue to be parallel and don't wind up converging.

I know I've improved a lot on this in the last couple years - I was that myopic jumper in my earlier years; I shudder to think of what could have happened. Now I keep an eye out for that myopic jumper and do what I can to avoid them - if I don't see that they see me and are moving along a path that will continue to keep us separated, I'll do whatever I can to create even more separation and let them have their space.

I'm perfectly happy to be the last one down, or the last one down before the tandems (who will almost always be waaaay above me and not an issue).


(This post was edited by NWFlyer on Jul 19, 2010, 2:52 PM)


AggieDave  (D License)

Jul 19, 2010, 3:06 PM
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

It all has to do with landing patterns and people's willingness (or lack there of) to fly them!

Active canopy piloting starts before you get in the plane. Although someone may be experienced enough to not need to draw out a landing pattern on a flight planner, they need to be aware of who is on the load. They should also have a very explicit idea of what landing pattern they are going to fly in relation to the spot, the winds and what the load is. They also need to have a rough idea of what the person is jumping and where they will fit in the "school of fish" for landing.

This isn't necessarily an exact science, but if you're in the loading area for an Otter and see someone wearing a very small rig with a camera helmet and interviewing a tandem student, there is a fair chance that the person could overtake you in the pattern. So you should be aware of that possibility and look for that person in your holding area prior to entering the pattern.

Your entry into the landing pattern should have started upon deployment. Instead of racking off a handful of spirals for fun, go into half-brakes, knock out a couple of flat turns while actively scanning the sky above, below and behind you, to get a good idea of where the canopy spread is and an idea of where possible canopy conflicts may occur.


tkhayes  (D 18764)

Jul 19, 2010, 4:11 PM
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

fly the pattern, fly defensively. make yourself visible. respect others, have a plan B every step of the way.

faster parachutes, more of them in the air. This is not new, it is simply human mistakes we make. There will always be there, but until we figure out a way to teach it and standards to follow for any given jump on any given dropzone - we will see this from time to time.

But we can greatly reduce it.


Premier NWFlyer  (D License)

Jul 19, 2010, 4:16 PM
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Re: [tkhayes] Why do we keep colliding? [In reply to] Can't Post

Quote:
make yourself visible.

Oh yeah, forgot that one! I went from a "stealth mode" black canopy with red ribs to a "damn that's obnoxiously bright" yellow/orange canopy. Laugh


JohnRich  (D License)

Jul 19, 2010, 4:20 PM
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Re: [Inspired] Why do we keep colliding? [In reply to] Can't Post

In reply to:
I just recently had it pointed out to me that I was flying in another jumper's blind spot. Not a safe place to be. Lesson learned: It's not just about me knowing where they are. It's also about making sure they know where I am.

Good point.

If you're in that kind of position with another canopy, then you've got to REALLY keep an eye on them, because...

...many jumpers don't bother to look over their shoulders before they initiate a turn or a spiral, to see if there is anyone else in the way, where they are about to go. They just do it, and react later. I don't know where that mindset comes from, but you see it in other activities also, like jet ski boats.

Many people are idiots. If you don't want to be killed by an idiot, stay the hell away from them.

Note: Everyone can be an idiot.


(This post was edited by JohnRich on Jul 19, 2010, 8:12 PM)


Premier billvon  (D 16479)
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Jul 19, 2010, 4:39 PM
Post #9 of 33 (1723 views)
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

> Why do we keep colliding?

I believe one reason is the ever-faster progression to smaller canopies. People downsize rapidly and everything seems fine to them until they're in the air with other canopies in close proximity. Then things start happening a lot faster than they are used to, and a collision becomes a lot more likely.

The most common instance of this I've seen is the case of the small canopy overtaking the larger one. When Joe Jumper was on his bigger canopy, either people passed him (and become non-issues shortly after they passed him) or he kept up with people, and if he started with separation generally he tended to keep it.

Now Joe has a new Samurai 150 and he loves it. He's passing all those slow old canopies. He's "being careful" and flying solid patterns, and everyone tells him he's doing great. But his awareness isn't very wide yet.

So one day he's on final and he's closing on a big old canopy. He decides to "be safe" and give the lesser jumper a wide berth. He keeps his eyes on the threat of the bigger canopy as he turns away from it - right into someone else who was on the other side of him.

In heavy traffic (i.e. bigways) you can see this effect ripple through the pattern. The guy jogs left, the guy next to him jogs left even more, the guy behind both of them gets erratic as he tries to figure out where to go, the guy behind HIM goes into brakes to give himself some more time. At times like this, a lack of awareness becomes deadly pretty quickly.


psf  (C License)

Jul 19, 2010, 8:28 PM
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

perhaps now is a good time to mention that I disagree with USPA teaching that the number one priority is to pull, pull at correct altitude, pull at correct altitude while stable, but rather TO LAND SAFELY UNDER AN OPEN PARACHUTE.


Premier NWFlyer  (D License)

Jul 19, 2010, 8:54 PM
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Re: [psf] Why do we keep colliding? [In reply to] Can't Post

In reply to:
perhaps now is a good time to mention that I disagree with USPA teaching that the number one priority is to pull, pull at correct altitude, pull at correct altitude while stable, but rather TO LAND SAFELY UNDER AN OPEN PARACHUTE.

Yes, but you can't do the latter unless you do the former (AAD fires notwithstanding).


happythoughts  (D License)

Jul 19, 2010, 8:58 PM
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

One thing that helps is to look around immediately after opening. Don't do the busy-stuff (sliders, booties, etc).
Grab your rears and start looking for traffic. Do the other stuff after you are sure that you are clear.

Second, don't spiral over the main landing area.

Third, look before you do a spiral, or fast turn, anywhere.


bucketlistpilot  (C 1204)

Jul 20, 2010, 2:02 AM
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Re: [NWFlyer] Why do we keep colliding? [In reply to] Can't Post

In reply to:
Quote:
make yourself visible.

Oh yeah, forgot that one! I went from a "stealth mode" black canopy with red ribs to a "damn that's obnoxiously bright" yellow/orange canopy. Laugh

Know what you mean. My mate's flying it now in New Zealand. It doesn't really jump out at you does it.


davelepka  (D 21448)

Jul 20, 2010, 5:14 AM
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

 
Canopies are getting faster, and jumpers are not. The faster a canopy gets, the more room you need to fly it, and the last time I checked, LZ are not getting any bigger.

As other have mentioned, flying a pattern is the first step. If everyone is flying the same direction, it's tough to have a 'collision'. You may end up with a 'bump' or a 'graze', but a full-on collision requires the type of speed differential you can only achieve by two canopies flying in two different directions. If everyone was flying in a single-file line, using common turn points, collisions would be much less likely, you just wouldn't have the closing speed to 'collide'.

To take that idea one step further, you need to be GOOD at flying a pattern. If you set up your pattern incorrectly, now you have to either cut the corner or swing wide to make it work, and thus you are exiting and entering the pattern, creating a speed differential.

If you want to look at the LZs, and consider that we are flying unpowered craft, you would need to make provisions for jumpers who cannot make the pattern area, like a zone on either side of the main LZ where you can approach from either side without using the pattern. The truth is that there would just be an alternate type of pattern in these areas, more of a straight-in type of pattern, but seeing as soemtimes you can't make the pattern, there either needs to be an alternate area for you, or again, you'll be entering the pattern from an odd angle and creating the speed differential that can lead to collisions.

Of course, as the USPA has already suggested and some DZs have already done, swoopers need their own LZ as well. If you want to talk speed differential, the swoopers have the market cornered. The DZ I jump at has a high performance LZ, but it's tight, and no place for a guy new to swooping, so we end up with the new swoopers out in the main LZ with the general population.

So to review, what we need is jumper training and discipline, segregated LZs with a main pattern zone, two alternate zones for straight in from either direction, and a zone for swoopers.

Does that exist any any DZ anywhere in the world? The answer is no, and that's why we keep colliding.


(This post was edited by davelepka on Jul 20, 2010, 5:16 AM)


kallend  (D 23151)

Jul 20, 2010, 5:44 AM
Post #15 of 33 (1481 views)
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Re: [billvon] Why do we keep colliding? [In reply to] Can't Post

In reply to:
> Why do we keep colliding?

I believe one reason is the ever-faster progression to smaller canopies. People downsize rapidly and everything seems fine to them until they're in the air with other canopies in close proximity. Then things start happening a lot faster than they are used to, and a collision becomes a lot more likely.

The most common instance of this I've seen is the case of the small canopy overtaking the larger one. When Joe Jumper was on his bigger canopy, either people passed him (and become non-issues shortly after they passed him) or he kept up with people, and if he started with separation generally he tended to keep it.

Now Joe has a new Samurai 150 and he loves it. He's passing all those slow old canopies. He's "being careful" and flying solid patterns, and everyone tells him he's doing great. But his awareness isn't very wide yet.

So one day he's on final and he's closing on a big old canopy. He decides to "be safe" and give the lesser jumper a wide berth. He keeps his eyes on the threat of the bigger canopy as he turns away from it - right into someone else who was on the other side of him.

In heavy traffic (i.e. bigways) you can see this effect ripple through the pattern. The guy jogs left, the guy next to him jogs left even more, the guy behind both of them gets erratic as he tries to figure out where to go, the guy behind HIM goes into brakes to give himself some more time. At times like this, a lack of awareness becomes deadly pretty quickly.

I've not seen any data to suggest that canopy size/WL has much to do with collisions. Flying style (270s in the standard pattern, spiralling, trying to land close instead of walking back etc.) has been involved in any number of collisions, however.


wmw999  (D 6296)

Jul 20, 2010, 5:58 AM
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Re: [kallend] Why do we keep colliding? [In reply to] Can't Post

Not sure about data, but I would imagine that the wide variety of canopy speeds and descent rates also has something to do with it. Back when everyone jumped lightly loaded canopies, your speeds weren't different enough to worry as much.

With more variables that have a wider possible range of values, it's more complicated.

Wendy P.


kallend  (D 23151)

Jul 20, 2010, 6:30 AM
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Re: [wmw999] Why do we keep colliding? [In reply to] Can't Post

In reply to:
Not sure about data, but I would imagine that the wide variety of canopy speeds and descent rates also has something to do with it. Back when everyone jumped lightly loaded canopies, your speeds weren't different enough to worry as much.

With more variables that have a wider possible range of values, it's more complicated.

Wendy P.

You get more difference in speed by throwing a 270 than you do by doubling your wing loading.

I wonder if the two septuagenarians killed over the weekend had aggressively downsized?

Seems to me that WL is becoming the PC scapegoat for many problems that really have other causes.


base283  (D 15343)

Jul 20, 2010, 6:46 AM
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

"MakeItHappen" posted this http://www.dropzone.com/...;page=unread#3908826 in the other thread and I do not see any validity in this quoted statement:
Quote:
Larger canopies with a low wing loading have a steeper approach compared to smaller canopies with a high wing loading.
.
Can someone enlighten me?
Take care,
space


wmw999  (D 6296)

Jul 20, 2010, 7:08 AM
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Re: [kallend] Why do we keep colliding? [In reply to] Can't Post

I wasn't blaming wingloading; I was blaming all the different variables introduced by varying rates of forward and downward speed. And yes, spiraling and 270's would definitely add.

The autobahn works because everyone is going fast and in the same direction. A bumper car amusement ride works because everyone is going slow and is well-protected (well, sort of).

We'd like to evolve to the autobahn model, but sometimes it looks more like bumper cars. In 3-D.

Wendy P.


BillyVance  (D 18895)

Jul 20, 2010, 7:56 AM
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Re: [theonlyski] Why do we keep colliding? [In reply to] Can't Post

In reply to:
In reply to:
Again this weekend 2 canopies converged on eachother and 2 more are gone.

UnsureOver and over it's preached 'keep your head on a swivel', 'it's not over until you're on the ground'Unsure

Not even over once you're on the ground. Pirate

Absolutely. I have been hit twice right after landing, and I hadn't taken any steps yet. Luckily, there were no injuries, but there were plenty of space to land on away from me. Target fixation, tunnel vision or whatnot is never good in the sport. Unsure


Premier billvon  (D 16479)
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Jul 20, 2010, 9:42 AM
Post #21 of 33 (1368 views)
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Re: [base283] Why do we keep colliding? [In reply to] Can't Post

>>Larger canopies with a low wing loading have a steeper approach
>>compared to smaller canopies with a high wing loading.

>Can someone enlighten me?

This is not true in general. Generally smaller canopies have steeper glide slopes because as area (and thus drag) on the parachute decreases at a given speed, the area of the jumper does not. So the L/D goes down as the parachute gets smaller. This can be affected by jumper drag, other parasitic drag (slider stowing/removal, riser preparation etc.)

That being said, there are a great many things that influence glide. A Stiletto will glide further than a Katana because it is trimmed flatter. Comparing those two parachutes, even a small Stiletto would likely have a flatter glide than a larger Katana.

Compounding this is wind. Smaller parachutes will maintain a better glide over the ground when flying into the wind. Larger parachutes will maintain a better glide over the ground when flying downwind.


kallend  (D 23151)

Jul 20, 2010, 10:38 AM
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Re: [billvon] Why do we keep colliding? [In reply to] Can't Post

In reply to:
>>Larger canopies with a low wing loading have a steeper approach
>>compared to smaller canopies with a high wing loading.

>Can someone enlighten me?

This is not true in general. Generally smaller canopies have steeper glide slopes because as area (and thus drag) on the parachute decreases at a given speed, the area of the jumper does not. So the L/D goes down as the parachute gets smaller. This can be affected by jumper drag, other parasitic drag (slider stowing/removal, riser preparation etc.)

That being said, there are a great many things that influence glide. A Stiletto will glide further than a Katana because it is trimmed flatter. Comparing those two parachutes, even a small Stiletto would likely have a flatter glide than a larger Katana.

Compounding this is wind. Smaller parachutes will maintain a better glide over the ground when flying into the wind. Larger parachutes will maintain a better glide over the ground when flying downwind.

And the smaller high performance canopies generally have better shaped leading edges (much lower drag) than large student canopies or accuracy canopies. Look at the size of the openings at the nose of, say, a Velocity compared with an accuracy canopy. Also they have shorter lines, and line drag is significant.

On the subject of trim, I have a Spectre135 and a Storm135, both 7-cell slightly elliptical. The Storm has a far steeper glide than the Spectre on account of its trim, and the Spectre in turn is steeper than my Stiletto150.

All that being said, I still don't see any data suggesting that canopy choice per se is responsible for an increase in collision frequency, rather than jumper behavior, such as swooping in the pattern, or spiralling into it like the guy who hit me from behind.


(This post was edited by kallend on Jul 20, 2010, 10:47 AM)


erdnarob  (D 364)

Jul 20, 2010, 11:50 AM
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Re: [airdvr] Why do we keep colliding? [In reply to] Can't Post

Because of lack of concern with the traffic. People often want to land nearby the hanger or the packing area even in a parachute crowded space. When you think you are alone, check anyway for traffic near you especially on the sides. You can be lower and be overtaken by somebody above you first but going down faster. Few times just before landing I got squeezed between another parachute and and obstacles. I yelled at the jumper to catch his attention but he kept on flying without noticing me. I had to change my direction angle at the delicate time before the touch down.Mad
Load organizers should put the emphasis on the traffic pattern and warn the jumpers about canopy collision. It is so silly to have survived to a beautiful skydive and get problem few second before landing.
Even if landing a parachute is a critical time when high concentration is needed, you have to avoid having a tunnel vision.
Also, if at a 1000 feet you realize that too many people are going to land at about the same time, pull your toggles at shoulders and hold it. Your parachute will stop descending fast and your horizontal speed will be quite decreased. When you estimate that it is your turn to go, resume your normal descent. I know you have the experience but everything I mention here is for the benefits of the readers.
I will have to practice what I am saying here soon since I am going at the Summerfest at Skydive Chicago. Smile


Premier billvon  (D 16479)
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Jul 20, 2010, 12:09 PM
Post #24 of 33 (1278 views)
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Re: [erdnarob] Why do we keep colliding? [In reply to] Can't Post

>Also, if at a 1000 feet you realize that too many people are going to land
>at about the same time, pull your toggles at shoulders and hold it.

While this is a great way to build in some separation when traffic is light and you are still high, I would recommend not doing this when actually in the pattern. The people behind you will have to do the same thing if they are close, and if their canopy loading is higher than yours, this may cause them to 1) get even closer to you, 2) have to go around you (and that just gets you more traffic closer to you or 3) stall (we saw a stall/spin/collapse due to something similar to this a little while back.)

(However, it is a good idea if the air above you is clear, you're at 1000 feet and have not entered the pattern yet.)


JackC1

Jul 20, 2010, 2:44 PM
Post #25 of 33 (1219 views)
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Re: [AggieDave] Why do we keep colliding? [In reply to] Can't Post

I agree with AggieDave. Dodging canopies starts before you get on the plane, by assessing the wind and the landing direction, judging who's on the lift, the exit order, who is likely to swoop and where you need to fit in.

Once you're open, the first order is not just to have you head on a swivel ready to avoid someone but to actively point your canopy in a safe direction so that people will find it much harder to fly into you.

Once you've done all your busy work like collapsing sliders etc. sit on deep brakes and look for all the other canopies on the lift (you should know how many there are) and watch the landing order develop.

If you adjust your decent rate by flying on varying amount of deep brakes you should be able to pick the point at which you want to enter the pattern and not have it dictated to you because you've been flying on full drive all the time.

It's not guaranteed but it's the best I got.


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