attn: all new jumpers - fun stuff to try out

[Ron 10]

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well IMO if you fly straight you have bigger chances to cross someones flightline, whereas with a slow turn you will tend to stay in your area...

Valid thought...But try this.

Take a piece of paper, and imagine a 4 way. They break off, and turn and track. Now draw the break off and then the deployment. Draw circles around all of them. do the circles increase or reduce the seperation of the jumpers?

Now do the same thing and draw straight lines....Some math guy can fiqure the chances of two of the 4 picking courses that will cause them to collide....I think it is quite small.

And if you stay on a straight course, you only have one collision possible...However, if guys are turning then every revolution can cause a collision....You are in essence keeping the people closer and increasing the number of opportunities to collide.

Now thats my thoughts...but I welcome other reasoning...

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[piisfish 140]

OK thanks for your explanation, it's quite valid too..

But with the spiraling, you reduce the risk of collision compared to the straight flight if you have an off heading opening and fly along the jumprun...

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[xavenger 0]

As long as those people on nippy little canopies don't "spiral down" in to someone on a dosile old bird like mine, sounds fine. I was in cloud once .. along with a lot of other people .. and someone spiralled down pant-wettingly close to me (profusely apologised on the ground I should add).

We're not supposed to jump through clouds in the UK either, but at all apart from 1 dropzone I have been to here it's relatively common practice. Don't get me wrong, no one really "goes out their way" to jump through clouds .. and likewise the DZ operators don't go out of their way to drop people through clouds ... but damn it's cloudy here .. and apart from 4-8 weeks of the year we have clear skies .. we'd never jump otherwise if we didn't..

[piisfish 140]

that's why I was talking slow spiraling, gentle flat turn...

someone spiralling fast in clouds is very dangerous for sure...

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[Frenchy68 0]

But doesn't flying in a straight line potentially puts at least one of the jumper into the next group's kill zone? Meaning one of them may end up flying alogside the jumprun. Just wondering.

"For once you have tasted Absinthe you will walk the earth with your eyes turned towards the gutter, for there you have been and there you will long to return."

[Ron 10]

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But with the spiraling, you reduce the risk of collision compared to the straight flight if you have an off heading opening and fly along the jumprun...

I thought about that....One occurance, or one during every turn.

Also if you are in a cloud and turn...well you might just stay in that cloud.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[Ron 10]

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But doesn't flying in a straight line potentially puts at least one of the jumper into the next group's kill zone? Meaning one of them may end up flying alogside the jumprun. Just wondering.

Not an issue if the groups took enough seperation.

My fear of teaching people to turn in a cloud:

1. Might not turn slow, might turn fast. Pilots with instruments tend to screw up in cloud. It would be hard to ensure you are not GAINING speed by turning.

2. Turning in the cloud could KEEP you in the cloud. When you are flying a glider and hit lift, you turn to STAY in the lift. If you are in a cloud and turn...Unless you just flew in, by turning you might just stay in the cloud.

3. If you are close to someone, by turning you are risking hitting them...On every turn. With an off heading opening you *might* end up turning towards another jumper...If you are turning you *ARE* moving towards other jumpers at least half of your rotation.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[tombuch 0]

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My fear of teaching people to turn in a cloud:

1. Might not turn slow, might turn fast. Pilots with instruments tend to screw up in cloud. It would be hard to ensure you are not GAINING speed by turning.

2. Turning in the cloud could KEEP you in the cloud. When you are flying a glider and hit lift, you turn to STAY in the lift. If you are in a cloud and turn...Unless you just flew in, by turning you might just stay in the cloud.

3. If you are close to someone, by turning you are risking hitting them...On every turn. With an off heading opening you *might* end up turning towards another jumper...If you are turning you *ARE* moving towards other jumpers at least half of your rotation.

Interesting thoughts. I'm both an instrument pilot and a glider pilot, and have spent far too much time under canopy in dense clouds.

Your comment that the jumper might turn too fast, or might be disoriented like a pilot, is a potential problem with turns in clouds, but i don't think it is a serious concern. The key is to turn using toggle position. For example, a break turn, with one toggle at 1/4 breaks, and one at 1/2 breaks will deliver a specific level of performance and will not allow for a dive or stall. The turn is slow and shallow. When a pilot turns he has control over pitch, bank, and yaw, all at the same time, and unless trained with instruments is likely to loose control. Often what happens to a pilot when turning is that he pulls or pushes on the control device, causing a steep climb or dive. Likewise, a steepening bank will increase descent rate, and needs to be matched with back pressure. It's all a complicated dance in an airplane. A jumper has only one means of control, and can't change pitch or accidently force a stall. The key is for the jumper to fly with specific control inputs.

A glider pilot does makes turns to maintain altitude by remaining in a small column of rising air. It is possible, but very unlikely, that a jumper will climb while turning in a cloud. Lift is generated below a cloud, but lift is limited in a cloud, unless the cloud has has an unusually high level of energy (like a dense and towering storm cloud), and that will generally mean there is too much turbulence for us to be jumping. Conventional parachutes do NOT generate much lift, gliders do. While it's pretty easy for many parachute pilots to catch enough lift to remain over a runway on a hot sunny day, the same isn't true about riding lift in a cloud. It takes a huge amount of thermal activity to remain in a cloud, and sport parachutes can't really generate that level of lift. The threat of a climb while turning in a cloud is a theoretical concept that doesn't really apply to most skydiving situations.

Your suggestion that a continuous turn might drive a jumper toward another jumper is true if there is significant wind, and the second jumper is flying straight against the wind line. If both jumpers are turning they will shift downwind at the same rate, and shouldn't collide.

Flying straight would be a serious problem if two jumpers are flying at each other in full glide. Flying straight will also take a jumper far away from the spot, and will increase the likelihood of an off field landing.

A slow break/flat turn will keep speeds low, keep everybody in the same relative airspace, and keep everybody close to their opening point, and within a reasonable distance of the drop zone. Making noise while under canopy will allow nearby jumpers to avoid collisions, and if a collision happens, the slower contact speeds should make the impact less severe.

We have certainly covered some of the hazards of jumping in clouds!

Tom Buchanan
Instructor Emeritus
Comm Pilot MSEL,G
Author: JUMP! Skydiving Made Fun and Easy

[Ron 10]

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Your comment that the jumper might turn too fast, or might be disoriented like a pilot, is a potential problem with turns in clouds, but i don't think it is a serious concern

OK. Valid reasoning, and I agree that it should not be a problem.

I think we also agree that a fast spiral is a bad idea?

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A glider pilot does makes turns to maintain altitude by remaining in a small column of rising air. It is possible, but very unlikely, that a jumper will climb while turning in a cloud.

Maybe I wrote that badly...My issues with turning in a cloud is not that you could climb...Possible, yes due to convection. But I doubt thats any issue...My fear is that turning in a cloud will keep you in the cloud longer. Staying in low visability longer than a straight line out would provide.

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Your suggestion that a continuous turn might drive a jumper toward another jumper is true if there is significant wind, and the second jumper is flying straight against the wind line.

Again maybe I wrote that wrong.

Two jumpers in two turns that are close risk hitting more than two jumpers that are going straight.

If two jumpers are going straight they have one chance of hitting, two jumpers in a turn near each other continue to come close to each other.

Lets see if I can explain this better.

Take two pencils. Put them on the desk. There is a chance that they may cross. As two jumpers going straight may collide. But that is ONE possibility that they will be in the same airspace, at the same time, at the same altitude.

Take two CD's and put them on the desk...Due to the greater area of the disks...They may cross. Plus on every rotation of the jumper you risk flying into the other jumpers airspace. In essence you could fly into the other jumper once on EACH rotation...as opposed to one chance on a straight line.

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Flying straight would be a serious problem if two jumpers are flying at each other in full glide. Flying straight will also take a jumper far away from the spot, and will increase the likelihood of an off field landing.

In either case I think we agree that using brakes to reduce the potential energy of a collision is the right idea.

As for an off field landing...I'd rather land off, than collide.

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A slow break/flat turn will keep speeds low, keep everybody in the same relative airspace, and keep everybody close to their opening point, and within a reasonable distance of the drop zone.

See this is where we dissagree...I don't want to be in the same airspace, or close to the same point if I can't see them. I want to go to half brakes to reduce speed, and get away from them if possible...I see a circular path of both jumpers just increasing the possible collisions.

Did I communicate it better this time?

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Making noise while under canopy will allow nearby jumpers to avoid collisions, and if a collision happens, the slower contact speeds should make the impact less severe.

Agree 100%

Interesting discussion.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[tombuch 0]

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Maybe I wrote that badly...My issues with turning in a cloud is not that you could climb...Possible, yes due to convection. But I doubt thats any issue...My fear is that turning in a cloud will keep you in the cloud longer. Staying in low visability longer than a straight line out would provide.

Well, your rate of descent decreases, so yeah, you will be in the cloud longer, but you will be remaining in relatively the same airspace. I'd rather stay where I'm alone and pretty safe, than move aggressively to a possible collision.

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Two jumpers in two turns that are close risk hitting more than two jumpers that are going straight.

You explained it better, but I think the risk of two turning parachutes colliding is still very small, as long as they have adequate separation when they start. The risk of two parachutes colliding when traveling in a straight line is also very small. The risk of one parachute colliding with any of many, if all are traveling in their own straight lines is much greater. Take your two pencils, then add 18 more. As long as the circles are small, and the pencils begin far enough apart, they will not collide. If 20 pencils vector toward each other, the risk of collision is much greater. So perhaps when jumping a Cessna a straight line works, but when jumping in larger groups, starting with separation and then holding position works better.

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As for an off field landing...I'd rather land off, than collide.

I'd rather not do either. We often think of landing off as not being a big deal, but it is. At my drop zone we recently tracked injuries and found that while less than 2 percent of our landings were off field, roughly 25 percent of our serious injuries were off the field. I wrote about the issue here: http://ranchskydive.com/safety/tb_article16.htm. Exiting the clouds over unfamiliar ground can be a serious problem, especially for inexperienced jumpers.

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See this is where we dissagree...I don't want to be in the same airspace, or close to the same point if I can't see them.

And I'd rather have my own airspace and let everybody else have their own airspace. I'd rather we hold relative positions at slow speed until visibility improves.

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Interesting discussion.

Yup.

Tom Buchanan
Instructor Emeritus
Comm Pilot MSEL,G
Author: JUMP! Skydiving Made Fun and Easy

[DontPanic 0]

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I still did my contolability check and then remembered what my instructor had told me to do and pulled hard on the right toggle to spiral through the cloud.

Is this the standard advice to give if someone finds themselves in a cloud? It is contrary to my views and practice.

Contrary to my practice too.

I like the concept of a sloooooooow spiral in breaks. The gental turn keeps each jumper in one small piece of airspace, and will hopefully prevent collisions. Going sloooow helps minimize the adverse effect of a collision, if one happens.

The other nice piece of advice is to make noise by yelling or singing, so anybody nearby can hear and avoid you. Pick a song and sing it at the top of your lungs ("...Madmen, drummers, bummers, and indians in the summer with a teenage diplomat...")

And the really best advice is to avoid clouds. That is especially true for instructors who are jumpmastering students.

With all that said, please follow the advice of your own instructor. If you think slooooow turns make more sense, then discuss it with your instructor, but if you are a student please do not follow random advice from the web.

Cloud avoidance was emphasized first, but I was taught to turn hard in a cloud to bleed off altitude (and to make plenty of noise). The reasoning behind this was due to potential for strong updrafts in the cloud formations that can actually take you back up to a much higher altitude. This may be a regional issue, since the cloud formations here on the Gulf Coast are more likely to have strong updrafts in them.

[Ron 10]

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Cloud avoidance was emphasized first, but I was taught to turn hard in a cloud to bleed off altitude (and to make plenty of noise). The reasoning behind this was due to potential for strong updrafts in the cloud formations that can actually take you back up to a much higher altitude. This may be a regional issue, since the cloud formations here on the Gulf Coast are more likely to have strong updrafts in them.

Hard turns are bad due to you build up speed and increase the amount of energy that will result in injury if you hit someone.

You *might* go up in a strong updraft....But that just means more time...A high speed impact can kill you.

Talk to your instructors about this...This may be something they tell students who are mostly alone in the sky...The rules might be different for you once you are in groups.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334