Forums: Skydiving: Safety and Training:
"Compressed Cabin" theory is not based on PHYSICS.

 


diverdriver  (D 19012)

Jun 30, 2004, 2:43 PM
Post #1 of 18 (2952 views)
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"Compressed Cabin" theory is not based on PHYSICS. Can't Post

Those of you flying in Cessna 182s and 206s that don't even have seatbelts installed because "it's so crammed you can't move" have GOT to get your head out of the sand. This theory is JUST as bad as the 45 degree rule for obtaining exit seperation. It is NOT based on physics.

If your jump plane is not equipped or other jumpers refuse to use seatbelts in your jump plane DO NOT GET ON THAT PLANE! This is not a rant but a plee for you all to listen.

Look at these accident reports from a long time ago. We MUST learn from the past! You will use your buddies at the front of the plane as airbags to save your life if you are not wearing seatbelts.

16 Fatal in 1992: http://www.ntsb.gov/...1211X14468&key=1

12 Fatal in 1992: http://www.ntsb.gov/...1211X15678&key=1

Improper use of a seatbelt in a 182 that ejected a jumper during a crash this year: http://www.ntsb.gov/...0226X00242&key=1


ScratchTX  (A 37215)

Jul 1, 2004, 8:26 AM
Post #2 of 18 (2760 views)
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Re: [diverdriver] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

How snug do the seatbelts need to be to be useful? Is threading through a leg strap or main lift web effective if it still allows a lot of movement? In many planes, depending on where I am sitting and where the seatbelts are attached, I end up with what seems like a lot of potential motion anyway -- either from a long seatbelt tightened over my lower legs, or from a seatbelt where the bottom of each side of the belt attaches to the plane in the same place, and I attach it around my harness. I'll still use them because I get why they're important, but I wonder how much help they would be in a crash. (This is not just for 182's and 206's, but other planes as well.)


Premier billvon  (D 16479)
Moderator
Jul 1, 2004, 9:08 AM
Post #3 of 18 (2746 views)
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Re: [ScratchTX] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

>Is threading through a leg strap or main lift web effective if it still allows a
>lot of movement?

It's more to protect others from your body than to protect you. A belt across your lap is going to be ideal; a system that connects to your harness in two places is going to come in second. The single-belt-through-the-lift-web will keep you from becoming a missile and will keep the CG within limits even during an impact, but is less useful for personal protection since an impact would generate high rotational rates.


chuckbrown  (D 19538)

Jul 1, 2004, 9:17 AM
Post #4 of 18 (2740 views)
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Re: [diverdriver] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

This link for the ejected jumper connects to a report regarding a jump plane crash caused by contaminated fuel.

You're absolutely right though. Seat belts are mandatory, not just from a legal perspective, but, more importantly, from a safety perspective.


ScratchTX  (A 37215)

Jul 1, 2004, 9:33 AM
Post #5 of 18 (2732 views)
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Re: [billvon] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

[reply
The single-belt-through-the-lift-web will keep you from becoming a missile and will keep the CG within limits even during an impact, but is less useful for personal protection since an impact would generate high rotational rates.
Thanks, that's what I was picturing. I might not become a missle but I imagined that with some restraint systems I could rotate far enough to slam into someone else pretty hard. In a small plane it seems I could still move half the length of the plane...Still better than unrestrained though, I guess, where there would be nothing to stop me and everyone else except the front cockpit wall.


flyboy62000  (D 29937)

Jul 5, 2004, 4:07 AM
Post #6 of 18 (2593 views)
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Re: [diverdriver] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

My personal feeling is that threading a single strap through a lift web or leg strap is about the same as wearing no seatbelt. Here where I live there are no regulations requiring seatbelt wear by jumpers. The lawmaking bodies here mostly figure that if you're going to jump from the airplane it's on you to manage your safety. I don't mind not having seatbelts and I'm no more worried about getting killed in a crash wearing with no seatbelt as an aircraft where you simply put a strap through your harness. I've responded to enough light aircraft crashes during my search and rescue days to know that if you go in in a small plane (182, 206, PA23, etc.), seatbelt or not you have a high probability of injury or death. Not trying to undermine anyone here, but I believe the effectiveness of other than a standard lap belt to be very slim.


piisfish

Jul 5, 2004, 4:22 AM
Post #7 of 18 (2589 views)
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Re: [diverdriver] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

I have never jumped from a porter equipped with belts, and some otters I've jumpe were not equipped either.
when a plane is equipped, i use the belts though.
same goes with helmets, on the head and closed or strapped to the chest strap.


riddler  (D 10234)

Jul 6, 2004, 10:00 AM
Post #8 of 18 (2506 views)
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Re: [piisfish] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

Quote:
I have never jumped from a porter equipped with belts

The one and only Porter I jumped from (Eloy holiday boogie, 2002) had seat belts for all positions. They actually made the ride quite uncomfortable, since the bolts on the floor were always jammed into my knee or ankle. I would still prefer seat belts, but that's the last time I plan to jump a Porter Unsure


gjhdiver  (D 7731)

Jul 9, 2004, 10:49 AM
Post #9 of 18 (2419 views)
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Re: [diverdriver] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

I'll wear any belt that restrains me, and not one that is attached loosely to an insecure point in the aircraft, whose sole function is to restrict me in the event of an emergency exit.


Premier billvon  (D 16479)
Moderator
Jul 9, 2004, 10:57 AM
Post #10 of 18 (2416 views)
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Re: [gjhdiver] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

>whose sole function is to restrict me in the event of an emergency exit.

Actually its sole function is to prevent you from being a missile and killing _me_. Wearing a seatbelt is not just for you.


gjhdiver  (D 7731)

Jul 9, 2004, 12:18 PM
Post #11 of 18 (2407 views)
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Re: [billvon] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

In reply to:
>whose sole function is to restrict me in the event of an emergency exit.

Actually its sole function is to prevent you from being a missile and killing _me_. Wearing a seatbelt is not just for you.

True, but I'm not wearing one that doesn't do that either, or will allow me just enough leeway to kill those behind me and no more.

There's not many restraints out there that actually do a whole lot. In fact, one plane I was in had lap belts that you would have slid out of instantly if the plane had braked hard, let alone crashed. I've been in others where you can't do your own, you have to rely on the person behind to clip and unclip you. I'm not going to do that either. What If I'm by the door, and person behind me is incapacitated, and I'm blocking everyone else ?

Like I said, I'll wear any restraint capable of doing it's job correctly. It's a pity that there are so few of them out there.


Premier billvon  (D 16479)
Moderator
Jul 9, 2004, 3:29 PM
Post #12 of 18 (2396 views)
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Re: [gjhdiver] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

>Like I said, I'll wear any restraint capable of doing it's job correctly.

No problem with that, but please have the courtesy to tell both the pilot (who can be fined by the FAA) and the other passengers (who you put at risk) that you will not be wearing it. They have a right to know the additional risk you are putting them at. Once you tell them, they can make their own decisions as to whether they want to take that risk.


gjhdiver  (D 7731)

Jul 12, 2004, 9:01 AM
Post #13 of 18 (2345 views)
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Re: [billvon] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

In reply to:
>Like I said, I'll wear any restraint capable of doing it's job correctly.

No problem with that, but please have the courtesy to tell both the pilot (who can be fined by the FAA) and the other passengers (who you put at risk) that you will not be wearing it. They have a right to know the additional risk you are putting them at. Once you tell them, they can make their own decisions as to whether they want to take that risk.

I do.


fudd  (C License)

Jul 12, 2004, 4:46 PM
Post #14 of 18 (2291 views)
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Re: [gjhdiver] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

It's not only to protect you from becomming a missile. It's to protect everybody from becomming a misile.
If two people don't wear them, then the person behind them will be hit by two bodies.
The idea is to secure the cargo to as many points as possible.
Also I imagine that if the plane gets in trouble and rolls, enter a dive or simular, it will be a lot easier for the pilot to gain control of the plane without five skydivers in the cockpit....


diverdriver  (D 19012)

Jul 12, 2004, 10:20 PM
Post #15 of 18 (2272 views)
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Re: [chuckbrown] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

In reply to:
This link for the ejected jumper connects to a report regarding a jump plane crash caused by contaminated fuel.

You're absolutely right though. Seat belts are mandatory, not just from a legal perspective, but, more importantly, from a safety perspective.


Yes, and during that crash because of contaminated fuel the jumper was ejected from the plane. This jumper was the "serious injury" listed on the report. The report itself does not describe the ejection but it did happen and the person has posted here on DZ.com about it. It surves as a warning to all to check that they are using their seatbelts and restraints in a way that will maximize their survivability.


DBCOOPER  (D 24112)

Jul 18, 2004, 6:14 AM
Post #16 of 18 (2196 views)
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Re: [diverdriver] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

The problem is that the seat belts were designed for use in a seat.The FAA and the TSO process prevent the use of restraints that would be much more effective than the lap belts typically used for skydiving.I jumped a Caravan in Belgium that had restraints that had the equivalent to an RSL release (only bigger)that could be hooked right on to a hip ring or thru a leg strap/lift web that appeared to offer a much better restraining ability than a typical lap belt.


Zenister  (A 42)

Jul 18, 2004, 7:39 AM
Post #17 of 18 (2189 views)
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Re: [DBCOOPER] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

exactly.

it seemed odd to see real 'seat belts' in aircraft with no seats, i always wondered why carabiners with locking gates and the proper webbing sewed to them were not used instead?? MUch more easily clipped on to hip rings and nearly bombproof unless dileberately removed.... till someone pointed out the legal certification process that would be nessesary first...CrazyMad


diverdriver  (D 19012)

Jul 19, 2004, 10:25 PM
Post #18 of 18 (2143 views)
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Re: [DBCOOPER] "Compressed Cabin" theory is not based on PHYSICS. [In reply to] Can't Post

In reply to:
The problem is that the seat belts were designed for use in a seat.The FAA and the TSO process prevent the use of restraints that would be much more effective than the lap belts typically used for skydiving.I jumped a Caravan in Belgium that had restraints that had the equivalent to an RSL release (only bigger)that could be hooked right on to a hip ring or thru a leg strap/lift web that appeared to offer a much better restraining ability than a typical lap belt.


I never said you had to use a regular seat belt that came standard with the plane. Of course we have to modify things so they are actually safe to use in our type of operation. My bad for assuming that this would make sense.



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