Do you teach or use this?

[Gary73 8]

Sometimes it happens that you find yourself under canopy over a large bad area (trees, water, etc.) on a day when the wind is parallel to the line separating the bad area from a large good area. The tendency is to crab toward your original target, but if the wind is close to your glide speed, you may not cover enough ground to make it to the good area before you land. On the other hand, if you turn perpendicular to that separating line, you'll make the best possible progress toward the good area, even though you may end up a good way downwind of your original target. (Please see attached diagram. And yes, that's about the limit of my artistic ability!) Is anyone else teaching this or using it while giving radio guidance?

"Extraordinary claims require extraordinary evidence." - Carl Sagan

[peek 20]

Maybe not in that much detail, but yes, I tell students that if the wind picks up and they are not making forward progress, or are even backing up, that sliding sideways (crabbing) may very well get them (or even back them up) to a better place to land.

[stratostar 5]

Yes I teach this and use the parasim to put them into just this type of condition. The cool thing about a parasim is you can pick different types of ground cover and weather conditions, exit altitudes, canopy sizes, WL, and mal's. This helps set up not only FJS's but EXP. jumpers as well to see how they would handle what you throw at them. It is good to not say anything and let them work it out, if they blow it all we have to do is restart the program and let them try again with instruction as to what they did wrong and what they did right. I find this makes for a better pilot in the long run and we see much better performance from our FJC's.

you can't pay for kids schoolin' with love of skydiving! ~ Airtwardo

[freeflygirlz 0]

I do all drawing of potential situations on our DZ's aerial pictures, as it is (imo) much easier for students to understand.
I always set up a simulated situation where they have to do, what you showed in your drawing.
blue skies
ffg

[riggerrob 558]

Let's see ... I have to chose between landing a mile down the beach or in shark-infested water?????
The answer is obvious!

[Gary73 8]

Gary,
Yeah, it's important to stay flexible in this sport, isn't it? Sometimes we forget that and focus too much on the original plan when there's a better answer right in front of us. Or right behind us!

Stratostar,
I've heard good things about the Parasim but never had a chance to use one. Too bad they're so pricey.

FFG,
I definitely agree about using overhead photos for both regular and "what if" canopy-control scenarios. In fact I just recently made some new ones for our DZ. Fortunately, Google Earth makes it pretty easy to get good images of most of the U.S. Their coverage of Austria isn't very high-resolution yet, but from what I can see it looks beautiful. I'll have to get over there someday.

Rob,
Funny that you should use that analogy: The first time I remember using this technique was after a cutaway a couple hundred yards out over the Gulf of Mexico with a strong wind blowing along the shoreline!

Unfortunately, sometimes people focus so much on getting to the original target that they fight a losing battle crabbing across a strong crosswind and come up short. Glad to hear that others are teaching this technique.

I generally agree with the standard method of moving the whole downwind/base/final landing pattern to a safe area when you can't get to the original target, but sometimes it takes all the running, holding, or crabbing you can do to get to a safe area. Sometimes you even have to skip that last turn and land downwind or crosswind to get to a good area, so it seems like a good idea to make sure that students (and radio Instructors) are aware of their options.

"Extraordinary claims require extraordinary evidence." - Carl Sagan

[popsjumper 2]

Gary,
Thanks for providing me with one more tool to use.

My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

[DougH 270]

You would cover even more ground with a running crab correct?

I was just thinking that depending on how deep you are over the trees having the wind partially at you back could further improve your glide with the right inputs.

"The restraining order says you're only allowed to touch me in freefall"
=P

[JohnMitchell 14]

Your picture is upside down. As the student looks at it, he has to mentally turn 180 degrees. Other than that, it's dandy. I teach the same thing, but walk through it with the wind pushing me and imaginary toggles in hand. I also use the chalkboard too.

[Gary73 8]

Andy,
Any time, man. See you at Dublin!

Doug,
Yes, your ground speed would increase, but the increase would all be down the wind line instead of across it, which is the goal in this particular case. (See attached second diagram.)

John,
I guess I don't understand. The drawing is a view from directly overhead, and the arrows are intended to indicate the directions the canopy is pointing and the wind is blowing. Perhaps the second diagram is clearer. Sorry, I'm not much of an artist and Microsoft Paint isn't much of a diagramming tool...

WRT the second diagram (attached to this post), when you're flying a canopy, your movement through the air (glide) and the air's movement over the ground (wind) are happening simultaneously, but sometimes it makes the situation more clear to draw them one at a time. In this case I drew the wind movement first, then the glide movement starting where the wind "left off". Examples are given of an upwind crab, a downwind crab, and a perpendicular (to the line separating the good area from the bad area) crab, with the dotted lines showing the actual movement over the ground. (Geeks will recognize this as a crude description of elementary vector arithmetic.) From that starting point, the canopy pilot can get to any point inside the Glide Range circle, but only a small portion of that circle is in the safe area. Note that this case shows a strong wind parallel to the separating line, but the same rule applies regardless of wind speed or direction: point the canopy perpendicular to the separating line to get the most movement toward the good area.

BTW, thanks, all: As is often the case, explaining this has caused me to re-think and hopefully improve how I teach it.

"Extraordinary claims require extraordinary evidence." - Carl Sagan

[JohnMitchell 14]

Quote

John,
I guess I don't understand. The drawing is a view from directly overhead,

My tongue was partly in cheek, but when I draw a canopy control diagram, I try to draw it so the student canopy is flying/facing towards the top of the board, same way the student in facing sitting in class. Easier to visualize? Dunno.

Canopy control is the most subjective part of the FJC, and one of the most difficult to teach well. I use chalkboard, miming, role playing, etc., and anything else I can think of. I usually lay a few props out on the carpet in the classroom and walk through a few patterns there. Radios and squares sure beat the old round parachutes and hope for the best, but you still have to train for the radio failure and off landing, don't you? I'm lucky to teach at a DZ that usually doesn't have too much wind.

[DougH 270]

Quote

Yes, your ground speed would increase, but the increase would all be down the wind line instead of across it, which is the goal in this particular case. (See attached second diagram.)

I was think less of ground speed, and more of an increase in glide path. I guess I need to break out Brian's book again.

"The restraining order says you're only allowed to touch me in freefall"
=P

[jakee 1,254]

Quote

I was just thinking that depending on how deep you are over the trees having the wind partially at you back could further improve your glide with the right inputs.

You would end up further down wind but no further (in fact less far) crosswind.

Do you want to have an ideagasm?

[dontiego 0]

I've heard (i have too low experience to have seen it myself, yes) that the organisation during a world record in thailand told jumpers that if they were above the sea with wind parallel to the beach, they had to fly perpendicularly to the beach.

It is the shortest path relatively to the ground... but not relatively to the air mass.

I guess that's what your drawing is about?

(I may have gotten the place and occasion wrong)

"We call on the common man to rise up in revolt against this evil of typographical ignorance."
http://bancomicsans.com

[Gary73 8]

Dontiego,

Yes, that's exactly what I meant. Who cares how far down the beach you land, as long as you do land on the beach and not in the water!

"Extraordinary claims require extraordinary evidence." - Carl Sagan

[Shyandinnocent 0]

I cover canopy control extensively before each jump. Most students are nervous about the jumping out and freefall, and seem more casual about canopy control ("desn't look too hard"), not realizing that it is the last inch that is going to hurt bad if you don't get it right.

So, yes, I also teach this. BUT I also teach my students not to go over bad areas in the first place. In the wind direction on your diagram there is no reason for my students to be over the bad area at all. We're a 182 DZ, and if I can't spot better than putting my student over tiger country, I shouldn't teach in the first place.
Having said that, sometimes students fly around thinking thay are one place, when they in reality are not, and lets face it: sometimes they just aren't thinking. In that case, I get on the radio straight away, and help them to safety, and then cover it all in the debrief. And the brief for the next jump, and that debrief, and so on.
I am all for giving students a chance to prove themselves, but if they are doing obvious stupid shit, I am not waiting for them to get hurt to make them learn a lesson!!
I do realize that this is different on DZs running big turbine aircraft, but surely you, as an instructor, have the resposibility (and authority) to ensure a good enough spot for your student?
Sorry, just looked at the original post, and realized I was a bit off topic!
IM

It's never too late for a low turn!

[Gary73 8]

I mainly agree with you. I'd like to see more canopy-control instruction in both the FJC and in later ground preps. I'm going to one of Scott Miller's courses next weekend mainly in hopes of learning how to teach CC better, and if I learn something new myself, all the better.

As for why anyone would end up over a bad area to begin with, you touched on one of the reasons: larger planes make it impossible for everyone to get the ideal spot. Other reasons that don't imply improper behavior on anyone's part might include:
First load; winds not as forecast
Winds changed since last load
Tracked in inconvenient direction
Flew wrong direction under line twists
Cutaway caused lower opening altitude

As for not flying over bad areas, I'll have to visit Queensland one of these days - I've never seen a dropzone that didn't have at least a few bad areas!

WRT Instructor responsibility and authority, yes, but a spot that's good enough for one student might not be for another. Lots of students do a great job in front of the overhead photo, then get totally disoriented in the air. Last Fall I saw a professional pilot fly directly away from the airport until I turned him around. Twice. "AFF is like a box of chocolates - you never know what you're going to get."

"Extraordinary claims require extraordinary evidence." - Carl Sagan