Aircraft emergencies - freefall and canopy collisions

[AggieDave 6]

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Fifty feet is WORSE than zero? How do you figure?

Closing speed is what will hurt or kill in that situation, an a wrap with a crapload of fabric out may still be survivable.

However, in an AC emergancy, its a moot point.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[relyon 0]

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Fifty feet is WORSE than zero? How do you figure?

Because of the momentum and closing speed that builds up at that range. In addition, a lot of off-heading openings tend to swing the jumper around like a pendulum. This all happens at a time when there is little to no control of the still deploying parachutes. At close range there is no room to build the speed, though a wrap or entanglement is possible. At 100 feet, there's enough time to turn.

Again, simply looking a making sure there is some vertical separation (20 feet is sufficient) will avoid any nastiness. That should be possible in all but the very lowest bailout situation (1000' or less). In that case, it's anyone's guess as to how it will end.

Bob

[dorbie 0]

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It would be less cool to take enough time that the last jumper exited the plane at 200 feet, or when the airspeed hit 300kts

No doubt!

I would rather take my chances under canopy then find myself in a situation in which we were now too low to get out because of some asshole that wanted better seperation. I would come back from the grave to kick his ass.

What a lot of folks don't realize is that bail out altitudes are different for different AC and the conditions are drastically different.

It also seems it's a mistake to assume that because the aircraft is in stable flight and you can reach and stand in the doorway that the situation won't deteriorate.

Get out when you can, it's just frigging obvious you shouldn't be waiting in the door. There's absolutely nothing to guarantee that you won't be pinned under a dozen skydivers in the nose of a spinning plane if you don't get out while you can. Altitude won't save you under those circumstances.

[freakydiver 0]

Interesting way to look at it, I'll take my 50 feet of horizontal as well as the vertical that comes with it.

-- (N.DG) "If all else fails – at least try and look under control." --

[Designer 0]

Humm,interesting question.Seems to me that everyone after the 1st person out "Should" face 90 opposite off from the last person.That is if everyone has on windline opening.Any thoughts?

[billvon 3,070]

>.Seems to me that everyone after the 1st person out "Should"
> face 90 opposite off from the last person.

I would disagree. Ideally you want to face the aircraft on exit. This is the position most people practice when doing poised exits, and it's the position that your main/reserve will open best in. If everyone opens on heading it's still not a problem (everyone's moving in the same direction with stowed brakes) and more importantly you will see the next person out. You can't avoid a jumper you don't see.

Of course, all this discussion is somewhat academic. It's like asking if you should use bottled water or tap water to put out your hair if it's on fire.

[Designer 0]

Think your right bill.Was thinking like being 45 off on exit from high alt. tracking away from all groups.Would this work in an emergency situation?No time,get out and open any way clear of everybody else?rob

[relyon 0]

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Of course, all this discussion is somewhat academic. It's like asking if you should use bottled water or tap water to put out your hair if it's on fire.

The part of the discussion I've been participating in - close proximity deployment collision avoidance - is only academic to those who have not seen or been in that situation. For those that have, it's very real and pertinent.

The analogy of water quality selection for extinguishing flaming hair is irrelevant.

Bob

[billvon 3,070]

>The part of the discussion I've been participating in - close proximity
> deployment collision avoidance - is only academic to those who have
>not seen or been in that situation.

Let me put it this way, then. If you balk on exit during a bailout to give yourself what you consider to be adequate separation, you are going to get trampled (or more likely, pushed out the door.) This will result in an unstable exit on top of someone else. Thus, while it may well be interesting to talk about what exit separation is appropriate, your two effective choices during a real bailout are a very short delay with a stable exit or no delay with an unstable exit. From my experience, a short delay with a stable exit works better.

[relyon 0]

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Let me put it this way, then. If you balk on exit during a bailout to give yourself what you consider to be adequate separation, you are going to get trampled (or more likely, pushed out the door.) This will result in an unstable exit on top of someone else. Thus, while it may well be interesting to talk about what exit separation is appropriate, your two effective choices during a real bailout are a very short delay with a stable exit or no delay with an unstable exit. From my experience, a short delay with a stable exit works better.

You seem to be hung up on a point I am not contesting. I have repeatedly addressed the issue of deployment separation, not exit separation. They are two different things. If two people deploy in close proximity and that results in the worst case scenario you describe (50 feet horizontal separation with one on-heading and one 180 off-heading), there is very likely going to be an uncontrollable collision that can injure or kill. I know plenty of people who have been in that situation, myself included, and referenced a double fatality caused by the same.

A good friend of mine was one of the survivors of the Silvana, WA Loadstar crash. By his account, none of the people who got out (16 in all) had anything that would be remotely considered a stable exit, nor did anyone balk at the door (the aircraft was stalling and flipping over). With the exception of the last person out (who pitched his PC while hanging from the forward door frame and got pretty banged up by it), everyone got clear of both the aircraft and one another before deploying. Clearly they had more than two choices.

Your experience? How many actual (not simulated) emergency bailouts have you been in, and how many times have you been in the worse case deployment scenario you described in your first reply?

Bob

[billvon 3,070]

>How many actual (not simulated) emergency bailouts have you been in . . .

Two actual. Cessna in 1993 and Otter in 2004.

>and how many times have you been in the worse case deployment
>scenario you described in your first reply?

I've opened within 50 feet of people (horizontal/vertical) perhaps 10 times out of about 4500 jumps. The ones that almost got me were the ones I didn't see. The ones that I saw the jumper on were scary but I had no problem avoiding the other jumper.