Landing accuracy for beginners

[kcb203 0]

I don’t understand how beginning skydivers are supposed to obtain the accuracy needed for the 10 jumps within 33 feet or 10 meters for the B license without doing anything on final to extend or shorten the glide ratio.

I just completed my B license canopy course and while I can repeatedly get within 100 feet or so, increased accuracy eludes me and I’ll explain with some trigonometry. I understand the visual trick of looking at the vanishing point to see what rises and what falls. I’m also applying what I learned that I shouldn’t be trying to extend or shorten my approach once I’m on final. So once I make that last turn, my final landing point is essentially already established.

Let’s assume a no-wind day and a canopy with a glide ratio of 2.5:1. That means when I turn to final at 300 feet, I need to be 750 feet from the target. But if I’m at 320 feet instead of 300 when I make that turn, I’ll land 20 x 2.5 or 50 feet long. To hit within 25 feet, my vertical accuracy at the turn needs to be within 10 feet, which is far beyond the resolution of an analog altimeter and although a digital one displays within 10 feet, I don’t think it’s possible to assume it’s always consistent and respond exactly as the digits flip from 310 to 300.

But let’s assume that I can always be over the right spot at exactly the right altitude for my turn to final, but the winds have changed by as little as 1.5 mph. So instead of no wind, we now have a 1.5 mph headwind, which is 2.2 feet per second. Let’s assume my canopy has a an airspeed of 30 mph, or 44 fps. At a 2.5:1 glide ratio, that’s 17.6 fps descent rate. Starting from 300 feet, my final approach is 17 seconds (300/17.6=17). With a 1.5 mph headwind, my final is now 37.4 feet short (2.2 fps x 17 second final approach). So even if I’m perfectly consistent and correct an approach that was 37 feet long on the previous attempt exactly, a 1.5 mph change in wind blows the 33 foot accuracy requirement.

OK, now some will say I need to use my eyes rather than rely on turning exactly at 300 feet in the exact same spot every time. Basic trig tells us that 300’ AGL at 750’ from the target is an angle of 21.8 degrees. But if my visual protractor is off by even a single degree, a 22.8 degree angle from the same 300’ is 713’ horizontally instead of 750’, and I’m 37’ short of the target.

And I’ve read TK’s accuracy seminar:
http://www.skydivestlouisarea.com/instruction/TKHayes_AccuracySeminar_042007.pdf

I don’t have the author’s experience, but I have to say I can’t agree with his conclusion that using the visual up or down trick works on base before turning to final. I’ll see the same gradual change from the target moving down to stationary to moving up as I’m on my base leg regardless of whether my canopy has a glide ratio of 1:1 or 3:1. But once I turn to final, those differences in glide ratio dramatically affect how long the horizontal distance of my final approach will be. I didn’t explain this well, but the visual transition when moving at 90 degrees from the target has no relationship to the glide ratio when moving toward the target and the accompanying visual image.

I know I’m overthinking this, but it just seems to me that getting consistent tight accuracy without any control inputs on final approach is a total crapshoot. Using consistency, visual cues, and instruments can help, but I just don’t see how to nail it every time.

After every landing, I pace off the distance to the target. I don't see anyone else doing this. Does everyone just guess, probably giving themselves a huge benefit of the doubt in the process?

[pchapman 261]

You're an analytical guy and I can see how it would be frustrating. I haven't checked your numbers but you see the flaw in the "ideal" situation.

There is the concept of not having to do anything on final, as the sort of ideal. That is, make your corrections during the turns to and from base and on base, but accept your final as is and use the skydivers "runway", no longer "shooting for the target" -- because nowadays one is often sharing the air with lots of people with different speed canopies. No longer 3 or 4 others from a C-182, who all jump canopies of similar low wing loading.

But is "no changes on final" actually in the US accuracy requirements for licences?? I don't know the US system.

Generally one is expected to "do something" on final in order if one is trying to be accurate! One is expected to use brakes in different amount, maybe even a little S turning. Maybe the DZ does have a target in an area suitable for students where there isn't a lot of other traffic.

If one is shooting accuracy in an off landing or a demo or in a competition, one is expected to do some maneuvering and braking on final.

[pchapman 261]

"I didn’t explain this well, but the visual transition when moving at 90 degrees from the target has no relationship to the glide ratio when moving toward the target and the accompanying visual image. "

I have also disputed TK's take on this, being able to come up with scenarios where the up or down movement of the target is not consistent with what changes one should make. At least, I think I did. So when I have done canopy courses, I have included his document as a reference -- but with caveats. Other than that stuff about up or down while on base, the rest is a good explanation.

As an example: You are flying a canopy that will have a 30 degree descent when flying into wind that day. As you go downwind past the target to the side, maybe 45 degrees down from you, it is moving UP all the time as you go further away and the angle becomes less. That doesn't mean you'll actually undershoot. You just haven't gotten to that 30 degree flight path yet, extending out downwind from the target. If there were no wind, one could think of it as a 30 degree cone from all sides converging on the target. (If there is wind, then the cone becomes an oval and calculations of the shape get messier.)

Same when you turn on base - If planned right, you'll still be above a 30 degree angle to the target. Thus, the target is moving UP as you get to a lower angle from the target. But that doesn't mean you are undershooting. Don't turn in on final yet, unlike what the document says.

(If the wind has increased and you actually should turn in now, while a little off the wind line, well, you don't know that for sure and could only guess from seeing more drift than you expected.)

If done right, you'll be getting close to the 30 degrees when you are nearly downwind of the target. Then you turn in, and assuming you accounted for some altitude loss in the turn, you can end up at the perfect 30 degrees (for this day's winds and your weight under your canopy). NOW if the target moves up you'll undershoot unless you can extend your glide a little.

Before getting on to final, you need to guess what angle of approach your canopy will give you that day, and try to intercept that angle of line downwind from the target. You can update your plans during the downwind and especially the base, as you gauge your drift speed. But it is still a bit of a guess when to turn in.

(A longer final gives you more distance and time to make adjustments, if that is part of the plan. But if you aren't going to be allowed to change much in the flight path, then a shorter final helps, as a given error in angle will result in less of an error in the landing spot. )

Yes it can help if the turn-in is gradual and close to the line downwind of the target -- then one can to a greater degree use the concept of seeing whether the target is going up or down and adjust from there.

I'm not sure of the math off hand, but turning based on whether the target is moving up or down I think really only works well when one is close to flying directly towards the target.

[mxk 1]

First, take a look at the accuracy requirements for the C license
Second, you're making a lot of assumptions that aren't going to hold in the real world. There are a lot of free and constrained variables, and when a few aren't ideal for an accurate landing, you can almost always compensate with others. Your turn to final does not need to be at exactly 300 ft. It does not need to be exactly 90 degrees. It can be slow to conserve altitude, or fast to dive the canopy and bleed off more energy (drag is proportional to the square of your speed). You can use your brakes, front risers, and small heading corrections (no S-turns!) on final. When you throw so many variables into the mix, plus all the corrections that you can make on downwind and base legs, the trig becomes far less straightforward.

Your Mk1 eyeball and brain are actually really good at "reading" the situation and figuring out whether you are going to overshoot or undershoot your target, but that internal sense takes time to develop. You're right that the target moving up or down on base doesn't give you completely accurate information because your velocity vector will be different on final, but your brain can still extract useful details from the visuals and from what it knows about the wind conditions. The more you pay attention to how things look in the pattern (don't forget to look around for traffic) and then combine that information with where you actually end up landing, the faster you will learn to land accurately.

I remember doing 30+ hop-and-pops in a row over many days for my C license accuracy. The weird part is that I would often land right in the peas on the first jump of the day, and then the remaining four or five jumps would be misses. Like I said, it just takes time, practice, and attention to detail.

Incidentally, the license accuracy requirement isn't really accuracy as far as I'm concerned. I landed right on target for my 25th and final AFF jump. I think you can probably guess whether that was skill or luck and whether I'd be able to do that a second time in a row. To me, accuracy means load 1 of the day, unfamiliar landing area, unfamiliar atmospheric conditions (except for the forecasts, METARs, etc.), you pick a target at 2,000 ft, land within 2m, and do that again the next day. That should be the goal. Take a look at the requirements for the PRO rating. There, you have to declare the accuracy jump ahead of time and land within the circle multiple times in a row, so this feat is entirely achievable.

[dthames 0]

As a student and A licensed jumper I would take an old tee shirt out into the field, far away from where most people landed and that was my landing target. I always turned with slow flat turns, which allowed me to work my pattern down a little lower (as time went on). On my base leg I would watch the target and keep asking myself, "where would I land if I turned toward the target NOW?" That turning point might be before I got to the ideal, 90 degrees from Final, or it might be a bit later than the perfect 90 degrees. Of course once I turned, a lot depended on the wind that day. As I learned to read the windsock better, I would make my base leg closer or further from my target, based on experience.

I would not allow myself to be sucked into the goal of adjusting my flight on final to make the target because I often there were still others to consider that were in the pattern. Also, it is a bad habit to get into.

For me it has always been very much, "Seat of the pants" type work. Just look where you want to land, fly there and land. Without very constant wind conditions, it is really hard to have a proven technical method that works.

I gradually improved. If you record your miss distance each time, you should see a gradual improvement. But some days are just better than other days.

Instructor quote, “What's weird is that you're older than my dad!”

[kcb203 0]

pchapman

"
(A longer final gives you more distance and time to make adjustments, if that is part of the plan. But if you aren't going to be allowed to change much in the flight path, then a shorter final helps, as a given error in angle will result in less of an error in the landing spot. )

That's an interesting thought. In some ways it seems like a final from 300' is harder than longer or shorter. If I had more time, I'd be able to look for the rising or sinking target and adjust accordingly without doing maneuvers too close to the ground. And if it was shorter, I could maybe time the turns better with less error due to being so far out. But 300', or about 15 seconds, doesn't leave much time to assess the rising or falling target, respond, and then have a good 8 seconds of full flight before flaring.

[gowlerk 1,904]

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without doing anything on final to extend or shorten the glide ratio.

Even experts do things on final to adjust. They just do more subtle things. On modern busy DZs the current practice is to avoid making any moves on final that could interfere with traffic behind you. And that is a good thing. When I was a beginner, on a Cessna 182 DZ we zigged and zagged across the windline as much as we wanted to get our accuracy. (we could be sure we were alone). I probably would have taken much longer to meet the requirements under the conditions you are being asked to do them with.

Your two tools that you can generally get away with using are to adjust the entry point onto final by extending or shortening your base leg. And using front risers if you are overshooting. Even with these small things you can be sure someone is going to reply and say that these moves are wrong as well!

Always remember the brave children who died defending your right to bear arms. Freedom is not free.

[pchapman 261]

kcb203

But 300', or about 15 seconds, doesn't leave much time to assess the rising or falling target, respond, and then have a good 8 seconds of full flight before flaring.

300' might be a number that gets mentioned a lot as an altitude to start being on final; perhaps avoid starting much lower than that for a newbie.

But it isn't like a requirement in all cases. So if you are working on adjusting your accuracy, it should be fine to set up further back and higher.

Due to DZ's with big planes and digital altimeters, there has been more emphasis on particular numbers in a circuit than there used to be. That's OK, but numbers can get overemphasized.

[tkhayes 125]

you're welcome

[Maddingo 21]

Damn, I'm a totally different guy, I do things how they feel inside some established boundaries. Use risers? I use them all the time and land quite consistently without zigzaging. Is the windsock up? U will go short, so turn faster, no wind, too long? Pull down the front risers for a couple of secs it will bleed 10-20m in a blink of an eye. I believe you can adjust your landing spot for a good amount of time on final and with some range.

[DJL 232]

Maddingo

Damn, I'm a totally different guy, I do things how they feel inside some established boundaries. Use risers? I use them all the time and land quite consistently without zigzaging. Is the windsock up? U will go short, so turn faster, no wind, too long? Pull down the front risers for a couple of secs it will bleed 10-20m in a blink of an eye. I believe you can adjust your landing spot for a good amount of time on final and with some range.

You really need to stop giving advice to new jumpers on the internet. People with 40 jumps ABSOLUTELY SHOULD NOT be doing anything with front risers on final.

kcb203, find a canopy course near you for direct coaching. Go out to the landing area as much as possible and watch landings. Don't copy anything you see that results in the canopy pulsing or surging.

"I encourage all awesome dangerous behavior." - Jeffro Fincher

[Hooknswoop 19]

TK-

Very nice presentation.

Derek V

[JohnMitchell 14]

A lot of good advice here. One thing I tell novices is what others have suggested above. If you have good canopy control and know how to do gentle and/or flat turns, move your turn to final lower. The 300' is for students as early as their first jump. With experience, you should be able to make your turn to final lower, safely

[JohnMitchell 14]

T.K., mind if I copy this?

JM

[sammielu 3]

Get in person canopy coaching.
Start your patten at the same place over the ground (in relation to your target) every time, and only change one thing at a time when you are working it out. Remember the wind already changes a bit on every single jump, so the fewer changes you make the more you'll identify what is working or not

Debrief the following after every jump:
-what was your landing plan?
- did you fly according to plan?
-if you did fly according to plan, did your plan work or do you need to make adjustments to your plan?

From a very basic level:
If you landed short, you need to conserve altitude and distance during your pattern. Tools to use: flatter turns, don't fly too far downwind, angle your base leg closer to the target, make your body smaller during flight.

If you landed long, you need to burn altitude during your pattern. Tools to use: faster turns (i.e. a deeper, faster 90 degree turn, don't use controls in the pattern you are not proficient with up high), angle your base leg away from the target, make your body bigger during flight.

PD Flight-1 teaches flying your pattern in 1/4 brakes (that's generally hands at your ears) to add an additional tool to use to travel farther or shorter; get some in person coaching from a good instructor on this one to be sure you're only using 1/4 brakes and not disrupting traffic behind you. On that note - you can make this all easier on yourself by holding in deep brakes as soon as you open to let the riff raff land before you and have the sky to yourself at landing (one less thing to think about).

Consider buying a Flysight to use for debrief and to track and plan your canopy flight skill building going forward. Best $250 I ever spent in this sport beyond the basics.

Edit'd to correct body position notes.

[unkulunkulu 0]

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If you landed short, you need to conserve altitude and distance during your pattern. Tools to use: <...> make your body bigger during flight.

If you landed long, you need to burn altitude during your pattern. Tools to use: <...> make your body smaller during flight.

I always thought it was the other way around. For example, when getting back from a long spot I usually use rear risers/toggles depending on the canopy and make my body as small and compact as possible to reduce drag. Is this line of thinking incorrect?

[tkhayes 125]

nope all yours. needs a few updates - been a while since i touched it up

[tkhayes 125]

PD and Flight-1 talk about that. with the wind at your back - or the wind in your face, rear risers work better that toggles in one of those situations, I cannot remember which is which but I want to add it to my presentation as well.

[SethInMI 145]

Now that sammielu edited his post, yours is really confusing now. :)

It's flare not flair, brakes not breaks, bridle not bridal, "could NOT care less" not "could care less".

[unkulunkulu 0]

tkhayes

PD and Flight-1 talk about that. with the wind at your back - or the wind in your face, rear risers work better that toggles in one of those situations, I cannot remember which is which but I want to add it to my presentation as well.

In tailwinds the minimum sink configuration must be best (probably achieved by quite deep toggles). In no wind you have to get best glide. In headwind it obviously depends on wind speed, in strong winds you might have to apply fronts.

The"depending on the canopy part" reflects a statement I'be been told and looks like unconsciously believed that my Sabre II should achieve best glide on toggles. Now that I think of it they must have meant the particular situation with tailwind and I should remove dependence on the canopy from that logic (although I believe there might be canopies like that).

[unkulunkulu 0]

SethInMI

Now that sammielu edited his post, yours is really confusing now. :)

sorry, can't edit or remove it anymore

[JohnMitchell 14]

unkulunkulu

If you landed long, you need to burn altitude during your pattern. Tools to use: <...> make your body smaller during flight.

make my body as small and compact as possible to reduce drag. Is this line of thinking incorrect?

You are correct. Anytime any flying object reduces its drag in any way, you will flatten your glide path some. It's the basic math that your glide ratio is actually your Lift/Drag ratio.

[Maddingo 21]

@djl Well yes I agree, but turning final means you still have around 100m of air. And you can make those correction in the first 20m.

[DJL 232]

Maddingo

@djl Well yes I agree, but turning final means you still have around 100m of air. And you can make those correction in the first 20m.

I look forward to when you're experienced enough to give people with 40 jumps good advice. Keep asking questions and getting involved but part of that is that you need to understand when you're wrong and swallow your pride. Don't tell people with 40 jumps on the internet to use front risers to correct their path on final (yes, even when they just turned to final). You have no idea what kind of equipment and situation they're working with.

"I encourage all awesome dangerous behavior." - Jeffro Fincher

[Christopherg 4]

As a current student I've been able to land with few feet of target 5-6 jumps so far. I've noticed even with wind it's almost like an instinct that you have that kinds helps me feel my way around up there to get as close as possible to target. Ive also noticed some people just cant figure out the pattern.Over all I've learned the stronger the wind the closer you want to stay to target. hanging in play area for a bit longer helps me when i notice wind picked up. Over all I have had 1 plf an i meant to attempt it so I know how to land. it really does help to just roll as instructed. seen some bad plfs since june