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Avoiding Object Strikes

This page is a chapter in 'BASE Wiki Malfunctions and Problems'

Avoiding Object Strikes: Recently I wrote the following email in response to some questions about customized deep brake settings and rear riser input. I’ve decided to post it here as some people may get some benefit out of it.

Remember that the contents of this document is VERY subjective. You should always draw knowledge from a wide source (plus your own experiences) when re-evaluating your plan on how to avoid hitting the wall on every single jump.

From LK:
>>I started jumping my Mojo with a new deeper setting, about 6 cm deeper than the factory deep. The canopy gets very sluggish on rear riser correction, just really doesn't want to turn but definitely stalls on the side with the correction. But it doesn't move very fast at all on opening, even during of headings. I have started to wonder now whether I should make avoidance manovers with toggle input instead of rear risers now, simply because I have slightly more time becuase of the decreased forward speed. Naturally it depends on the objects dynamics etc but I need to relearn my instinct of grabbing the rear risers all the time.

OK, this has saved my ass on about 4 occurrences with Mojo's:

[YOUTUBE]gIHr3gWsMVY[/YOUTUBE] 180 offheading - flying at wall - very close to impact. No time to turn away. Hard input on both rear risers. Canopy stalls backwards. Let up on left rear riser (while still pulling down on right). Canopy barely turns - cells are barely pressurized and there are waves going through the canopy. Reach across with left hand and pull down on front right riser (while still pulling down on right rear riser). This forces air into the cells - canopy instantly response and spins on the spot. Immediately let up on riser input and release brakes to drive away from the wall.

My importance list for avoiding a wall strike:

1. 180’s happen to all of us eventually. Do every thing you can to minimize the occurrence but resign yourself to the fact that they will happen. (Note: see the definition of Murphy’s Law).

2. Avoid smacking the wall at ALL costs.
Get the canopy to open with absolute MINIMAL forward speed. Forget all that sh*t about needing forward speed to get the canopy to respond to riser input. There is zero point to having a responsive canopy if you don't have the time to turn it away. Also the faster the forward speed of your canopy on deployment the harder you will hit the wall and the more bones will snap.

SLOWER forward speed is BETTER in 99% of serious offheadings close to the wall. Anyone who tells you otherwise has not had to deal with a bona fida 180, half line twists on a go-n-throw from a vertical wall. Factory installed brake settings on Mojo's are dangerous, dangerous, dangerous - even for the fastest BASE jumper in the world. Yeah - they work great for rear riser input on a 135 offheading, but turn it into a 160-180 offheading and the wall comes at you like a freight train. (Note: Adam does strongly recommend customizing your brake settings as the factory settings are extremely conservative. This is more of an issue with Mojo's than with FOX's due to the steep angle of attack on the Mojo).

3. Turn the canopy away from the wall.
In dealing with point #2 you have installed customized brake settings on your canopy (but not so deep that you risk a stall). Now because the canopy is going so slow you suddenly have response issues to rear riser input. Basically the thing won't want to turn and will probably stall if you pull down too hard on a rear riser.

The answer to this is not: make the canopy fly faster forward (read point #2 again). The answer is do something else to make the canopy turn away. Some people say "toggles". Well toggles are great (and my personal preference) if you aren't really close to the wall and flying directly at it. There are situations (eg. go-n-throw from vertical wall, bona fida 180 with half a line twist) where you do not have time to use toggles (I am NOT talking about the extra time to grab the toggles, I am talking about the response lag between releasing the brakes, pulling down on the toggle and the canopy actually responding). Also you may be so close to the wall that as you are turning away the end cell will drag on the wall and swing you back in. (I have seen this type of wall strike many times - and subsequently dealt many times with the resulting helicopter rescue, police, media, blah blah blah). If you are about to smack a wall nose on, the only thing to do is to back the canopy away far enough so that when you turn it, the end cell won't clip the wall. Flying the canopy backwards is the only option here (unless you are so low that you will pound into a ledge or the ground as you turn - in that case you just have to sink the canopy straight down and PLF - good luck).

In order to turn the canopy away the combination of both front and rear riser (with the brakes set) works really well. The canopy response almost instantly and just spins on the spot. Front riser input alone is a BAD idea as it makes the canopy dive forward and turn in an arc.

Note: In my experiences with the Vtec (and limited experience with the Blackjack) you usually don't need the front riser input as the vents keep the cells pressurized in almost zero forward speed and the canopy response great to rear riser input alone.

When to go for toggles and when to go for risers?
Basically here is my personal rule for that: If I open and I am flying at a wall and my body starts tensing up for immanent impact then I go for risers, otherwise I tend to go for toggles.

“Oh sh*t, whimper" on opening = risers.

"Uh Oh, I'm looking at wall" = toggles.

4. You aren’t good enough with the technology you are using to always avoid object strike.

With the current technology on the market NOBODY is good enough to avoid a wall strike every time. I have dealt with bad 180's close to the wall (sometimes with serious line twists) on many occasions (actually the number of times I have had 180's is downright embarrassing). I have never had my canopy touch the wall yet (I've pushed of the wall with my feet twice), but I am NOT stupid enough to think that I am good enough to deal with it every time.

Object strike is the number one incident that injuries highly experienced BASE jumpers when they haven't made a gross error of judgment. By plugging out thousands of BASE jumps we are playing a numbers game (if you jump vertical walls slider down). Statistics say that eventually you will hit the wall (Slim hit the wall three times in 1270 BASE jumps. Jump #1270 was the one that really f####d him up (but he's healing well and should be jumping next year). He probably has done the most slider down canopy deployments of anyone in the world and he is ULTRA FAST in dealing with offheadings). As the technology we are using advances (such as bottom skin vents, big grab toggles, vented pilot chutes) the odds are increased in our favor. All we can hope is that the technology increases at a faster rate than the numbers game we are playing.

Nice post Dwain - you have highlighted some excellent points about dealing with off-headings.

One of your comments did raise my eyebrow -- your statement about factory DBS settings on a Mojo being very dangerous. Even though you made a note about the fact that CR recommends that you test your canopy and subsequently customize your DBS settings, I disagree with your blanket statement about CR’s factory DBS settings being plain dangerous.

In my humble opinion, DBS settings are highly personal. There are many factors that contribute to DBS settings and their corresponding opening stall point. Weight (including ALL equipment), field elevation, wind speed and direction, are just a few of the constantly changing variables. Most jumpers forget these three variables alone when considering a DBS.

With that being said, I am of the opinion that it is better for a manufacturer to err on the side of conservatism in their placement of DBS settings and then, it is VERY IMPORTANT for a jumper to go out and run a series of very detailed tests to determine which DBS works for them.

I think it’s safe to say that 80% of jumpers out there do not take the time to do this properly. Quite frankly, I find this alarming.

For the life of me, I do not understand why some jumpers do not visit a span, or other suitable object, and experiment with their DBS to determine if in fact, the DBS is suitable for them and the environment they primarily jump in.

In my opinion, it is a responsible decision for the manufacturer to place conservative DBS on a canopy and then it is the responsibility of the jumper to determine what will work for them.

I’m sure you agree with most everything that I’ve listed above, but I simply wanted to throw my opinion into the mix and hopefully spur other jumpers into thinking about their DBS and whether or not they have truly explored its full-range of motion if you will.

Thank you for taking the time to share your insights with everyone. You have a lot of experience and hopefully jumpers who read your post will give considerable thought to their DBS and their approach to dealing with a serious off-heading.

Jumping off a span, I've tried both the shallow and the deep brake setting on my Fox. You say that it's important for a jumper to "go out and run a series of very detailed tests to determine which DBS works for them". There are a couple of things I'd like you to elaborate on, if you could:

1) What parameters would you recommend I observe in my tests? So far, I've mostly gone by the "feel" of the openings, and I have a qualitative idea of the differences, but I would have difficulty expressing those impressions quantitatively. What specific differences do you think I should look for?

2) What is the best way to experiment with brake settings other than the manufacturer's settings? I can easily experiment with shallow/deep settings which were installed by the manufacturer. Are you talking about experimenting with settings outside the ones set by the manufacturer? How would you do this?

I think there's a document in the CR library (on their web page) that discusses this, but here's how I find mine.
  1. Make a skydive on your canopy, with a fat tipped black felt marker tucked into your jumpsuit somewhere.
  2. Dump on exit so you have lots of room to play with the canopy.
  3. Pop the brakes, and play with the toggles until you find the stall point. This will take several stalls to establish properly, as you'll have to work back and forth across the stall point.
  4. Let up so the canopy is just barely flying (just above the stall point). Hold both toggles in one hand, and make sure you are flying straight (i.e. the toggles are even).
  5. Use the marker to mark the lines just below the keeper rings.
  6. Have your rigger (or the manufacturer) install a brake setting on the mark you made.
  7. Go to a big, friendly span, and jump those settings in a variety of conditions (especially tail and head winds, so you understand them).
  8. Modify them as necessary. This may take several trips back to the rigger.
Note that I generally like my DBS so deep that the canopy stalls when deployed in a decent tailwind, since the really dangerous (in terms of object strike) sites are solid, so a tailwind is pretty much impossible. This, though is personal preference (obviously, if you regularly jump low spans or antennas in tail winds, this won't be appropriate for you).

Anyway, that's how I do it. Anybody have an suggestions for ways I could do it better?

P.S. Although CR tries to customize the DBS on new canopies to your body weight, BR generally just has one "deep" setting for each canopy size, so setting your own DBS is even more important on BR canopies, at least in my opinion.

P.P.S. If anyone doesn't understand why there is no such thing as a "standard" deep brake setting, please post a follow up, and we can discuss that VERY important topic.

P.P.P.S In my opinion, anyone who doesn't customize their own DBS is destined to strike an object sooner, rather than later.

I generally observe the opening by having someone shoot video from above (preferably directly above), then looking at forward speed on opening (hopefully in calm winds).

A particularly useful way to do this is to do a full floater from a span in no wind, then film straight down and see if your canopy penetrates under the bridge before you can turn it.

I agree with what you are saying. My comment wasn’t intended as a criticism on CR, but more of a criticism on those people who do not follow CR’s recommendation and customize their brake settings
Yes CR needs to be conservative, as sending out a canopy with brake settings that may result in a stall is dangerous and personalized settings are a very hard thing to determine given the large number of variables.

I totally agree that CR has the right to say “It’s the jumpers job to customize their brake settings and we don’t hold any responsibility for object strikes which result from not doing this”.

However the fact remains that most BASE jumpers DON’T get their brake settings customized and I do believe that CR should take this into consideration when installing factory brake settings. I believe a less conservative factory setting on Mojo’s would result in several dozen less wall strikes per year. Perhaps there would be a couple more stalls but I believe the net injury would be far less with deeper factory brake settings on the Mojo.

But gear is advancing and this argument is rapidly becoming obsolete. From what I have observed (and experienced) the factory settings on the BlackJack is very deep and the canoy has very minimal forward speed on deployment.

We CRW guys use them all the time. My CRW toggles have the normal small grab with a large loop underneath (tandems have two loops to grab as well. This is very handy when doing "relatively fast rotations as you are rapidly changing from flaring to dropping toggles and catching lines, to applying brake in the stack, to tweaking a quick reverse left then right turn, followed by an aggressive front riser attack on the bottom of the formation, back to a flare, etc.

It is imperative that you stow the toggles VERY securely - if they come off they can wrap around your front / rear risers / lines. For BASE, you also have to ensure that the toggles are contained within the rig and not hanging out, and that they are packed clear of lines and material.

p.s the quick grab loop often has a stiffener in it to keep the loop open at all times.

p.s.s due to the weight of the stiffener, the loop can move around a bit during deployment (momentum). Its orientation will change which means you have to.

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