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  1. #1
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    Default Critique my rescue

    Hey all,
    Since we are all very good at analyzing other people's rescues I thought it'd be fair to put up one of my own for critique. It occurred last week, just outside Chicago in Cook County, Il. Backstory: Guy walked down a 20 ft + steep embankment full of basketball sized boulders to the river to go fishing. Just at the river's edge, he slipped on the unstable boulders and broke his fibula. We were dispatched as an ambulance only, and called for additional help in form of truck, engine, and BC (9 total personnel). Crew elected to utilize truck as high directional (previous great thread). Crew on scene included two TRT team members, as well 3 others with SPRAT level 1 and Rope Operations training. Crew decided not to pull the hook on a TRT call, which would have complicated the scene with incoming crews and was deemed unnecessary. From the time the truck pulled up on scene to time pt. was loaded into ambo was exactly 30 minutes. During the pt. packaging phase, crew overturned a boulder and stirred up a bee's nest, causing multiple stings to both pt. and rescuers, so there was some giddyup involved. Stokes was raised above the level of the bridge we were working off of, then lowered and tagged over to bridge level. Rope systems and operations went very smooth, with no problems....But, there's always room for improvement and certainly some things were not done as well as they could have been, so here goes

    Main Anchor: Truck rear outrigger (vertical column,) 2007 Pierce HD Tower Ladder Steel 100' 1000" tip load

    Belay Anchor: Truck rear manufactured anchor point.

    AHD: Manufactured anchor points on bottom of basket. 2 points, (1 for main, 1 for belay) each with a SWL of 500lbs. 10:1 safety factor

    Mainline: 1/2" anchored through an ID, up through redirected 2" pulley, down to stokes

    Belay line: 1/2" Munter (GASP!) on steel Pear-Shaped carabine, up through redirected 2" pully, down to stokes

    Stokes rigging: Traditional 4 legged adjustable bridle w/bull ring. Main and Belay attached via figure 8 knots to carabiners to bull ring. (again, not the most progressive method here, but worked just fine)

    Hauling System: 4:1 piggybacked on to mainline, progress captured with ID

    Lowering system: ID

    Tag line: Single line with double figure 8 knot, attached to stokes at pt. shoulder and knee level.

    See Picture Attached.

    Please let me know any comments or concerns you might. Hopefully this can generate some good discussion on modern best practices. Im also curious about how to determine the load generated at the high directional during the hauling phase with this particular set up.

    Thanks,
    Collin
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  2. #2
    Forum Member MichaelXYZ's Avatar
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    Hauling System: 4:1 piggybacked on to mainline, progress captured with ID
    How far was hauling system from redirect?


    Please let me know any comments or concerns you might. Hopefully this can generate some good discussion on modern best practices. Im also curious about how to determine the load generated at the high directional during the hauling phase with this particular set up.
    Wouldn't the load at the redirect just be the weight of victim and stokes x2, not accounting for angle of haul line? Or did I not understand question?
    Last edited by MichaelXYZ; 08-01-2012 at 03:22 AM.

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    Haul system was about 20 feet from the redirect. We should have done a low redirect and moved the hauling field into a more horizontal setup, but we ran out of pulleys...

    We determined the static load (with angle factored in) to be about 1.7 x the load or about 510lbs. Im more concerned with max force applied during the haul (dynamic) phase.

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    I'm just glad to see someone using what they learned and not trying to man handle a stokes or worse just the board up the rocks.
    Looks like a good job, we have the same tower and I don't feel you overstressed anything. I would have considered an attendant, just in case something happened to the patient in transit. With the guy horizontal it would really stink to have hime vomit on the way up and be in arrest by the time you get him up.
    But not a criticism, good job guys

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    One more thing, I think I would have used a load sharing anchor between the rings on the basket to prevent any twisting of the bucket and ladder.

    Again good job

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    There is 3000 ways to do any rescue.

    Want a critique?

    1) Succesful operation... rescued the patient.

    2) You operated in a safe manner, avioding injury (minus bee stings) to persons involved.

    3) You have identified deficiency, and hopefully learned from them.

    Every operation I have been involved in has always had room for improvement. That is why we are proffesionals, we are always willing to learn. Even a USAR team learns how to do something new or better after each evolution.

    Some suggestions?

    -Didn't call in the TRT? Maybe the right call, but I am under the mindset that even if you do not use an asset on scene, I would like to at least have them in route incase things take a turn downhill. Worst case senerio, they turn around and go home.

    -The bee hive... if avalible, class A foam does wonders on neutralizing bees. We also keep a can of bee/wasp spray on the rig in our driver's compartment.

    -I have no problems with the tequniques used. Might have rigges something simular, love the munter for a rescue load (if you have people trained to use it), and the ID is a versitle too also.
    ~Drew
    Firefighter/EMT/Technical Rescue
    USAR TF Rescue Specialist

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    Quote Originally Posted by MichaelXYZ View Post
    How far was hauling system from redirect?




    Wouldn't the load at the redirect just be the weight of victim and stokes x2, not accounting for angle of haul line? Or did I not understand question?
    Michael, differences in distance (20 feet, 40 feet, whatever) from the MA to the high directional will affect the number of resets needed. And if using nylon instead of poly, you'll have more stretch. But no appreciable loading differences at the high directional. I'll answer your second question in a comment to Collin.

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    Quote Originally Posted by EricUlner View Post
    Michael, differences in distance (20 feet, 40 feet, whatever) from the MA to the high directional will affect the number of resets needed. And if using nylon instead of poly, you'll have more stretch. But no appreciable loading differences at the high directional. I'll answer your second question in a comment to Collin.
    It was the number of resets which prompted my question. I was thinking the Z-rig would have made for less resets. I do not wish to take this thread off topic so I will add some questions in the 4:1 pulley thread.
    Thanks

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    Quote Originally Posted by collinmoon View Post
    Haul system was about 20 feet from the redirect. We should have done a low redirect and moved the hauling field into a more horizontal setup, but we ran out of pulleys...

    We determined the static load (with angle factored in) to be about 1.7 x the load or about 510lbs. Im more concerned with max force applied during the haul (dynamic) phase.
    Hi Collin,

    Looks like you got the job done successfully and well. Nice. I would offer that you didn't necessarily run out of pulleys. The pulley at the high directional for the belay line was the pulley you could've used for a CD at the anchor. The whole discussion of using a pulley in the belay system has already taken place in another thread, but I'll mention again... Using a biner instead of a pulley will reduce impact forces on both the high directional and the belay anchor. And the belayer wouldn't have to hold quite as tightly onto the Munter...

    You considering the static load at 300 in order to error on the conservative side? Or was your patient >270? Wow. No wonder you'd not want to do a low angle carry...

    As for the suggestion from ADSNWFLD to add a rescuer to the package, that's always a consideration, but you were on the scene, not us. I can see your decision as valid in your instance. We've raised similar injured patients out a canyon here in So. IL, but have elected to have an attendant. But that was due to the raise being 100 vertical feet and the patient already having an IV with MS on board. Different situations...

    Your question/concern of loading during hauling... And Mike's guess of 2x the load... In order to error on the conservative side, as I believe you did in considering a single person load of 300, I'd use IDEAL mechanical advantage (zero friction or 100% efficient pulleys) to figure out what I'm doing to my anchor while the load is not moving. Say I've a 100 lb. object hanging on a rope that runs above through an anchored pulley, and then back down to my hands. I'm holding the weight in place and it isn't moving. To error conservatively, I say that the pulley's anchor is bearing 200 pounds because I have to resist 100 pounds in order for the 100 pound object to not move. 100 on each side of the pulley combines to put 200 on the pulley's anchor. But in reality, if the pulley is 90% efficient, then I really only have to hold 90 pounds for the object to not move. So if I calculate using PRACTICAL mechanical advantage, I have 90 pounds on one side and 100 on the other, making 190 pounds that the pulley's anchor is really seeing. I can write it on paper as 100 pounds X 90% = 90 pounds and then add them together.

    But let's say that I instead apply 91 pounds to the rope instead of 90. Will that cause the 100 pound object to begin moving upwards? No. Well how much then? If I apply 101 pounds, will the 100 pound object begin moving upwards? Yes it will if I have a magic 0 friction pulley. Such doesn't exist. If you consider that the nicest pulleys on the market are in the 90% efficiency range (considering a 0 degree angle in the rope at the pulley), then calculate your anchor loading based on a factor of 0.9. In other words, I'll need to apply approximately 111 pounds to my side of the rope to make the 100 pound object begin to move upward, because 100 pounds is about 90% of 111 pounds. I can figure that on paper by flipping the math problem. 100 pounds divided by 90% = 111 pounds (and some change). So to error on the conservative side in figuring out what I'm doing to my high directional anchor while hauling is going on, I'll use practical mechanical advantage instead of ideal mechanical advantage.

    In your case, to make the 300 pound load move upward, it'll require 333 pounds (and a few cents). [Again, factoring at a zero degree angle to error conservative instead of your 65-70 degree angle that you implied.] The 333 will then be split up across the strands of your MA. So your high directional anchor is seeing roughly 633 as the load is moving upward. When you stop for reset, the ID needs to hold roughly 270 for the load not to move, using PMA (and at zero degrees above). But using IMA, you'd figure that at rest or during reset, the high directional anchor is simply seeing double the load. If you do factor in your rope angle, of course you'll see an even lower number at the high directional anchor during hauling.

    2 cents that I hope is helpful...

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    Quote Originally Posted by MichaelXYZ View Post
    It was the number of resets which prompted my question. I was thinking the Z-rig would have made for less resets. I do not wish to take this thread off topic so I will add some questions in the 4:1 pulley thread.
    Thanks
    Yes, essentially, the lower the MA, the less resets. But also the greater the need for bigger biceps...

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    Great topic. Thanks for being honest and sharing your experience. Great comments above. I will add a few more. I would consider upgrading your belay station to a technique that passes the belay compentance test. With a rescue sized load the munter is not consistent. Mike Gibbs from Rigging for Rescue performed loads of drop tests with the munter. Very frightening data for people still using this belay technique on rescue sized loads. Also its bad form to run your belay through a AHD, especially an aerial device. If at all possible run your belay on the ground, or over the bridge railing in your photo. Many will disagree with that opinion, but if you had a mainline failure and caught the load with your aerial the forces would be way over your working limits. It's not so much tip load as what you putting on the fulcrum. With out knowing your aerial extension in the photo, I'm guessing you could have as much as a 6:1 of the tip load down at the fulcrum. With slack in the belay this would be thousands of pounds in a dynamic situation. I know many will disagree, but there are plenty of ladder failure caused by this type of aerial tip loading. Just Food for thought. But like someone said above, you guys got the job done and everyone went home.
    Last edited by bottrigg; 08-03-2012 at 09:50 AM.

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    Collin, I'll add one more observation. I know it's commonplace in the rescue world, but using a biner to connect the belay rope to the package can be an invitation to a problem. This does depend on the type of carabiner used. If biner with a captive eye, then you'll prevent "funk" loading potential. If a typical oval or D biner coupled with an 8-on-a-bight, funkness can happen to the biner since a belay rope is not a loaded rope during operation. Direct tying of rope to package can be ideal. If time is of issue, and a biner is called for, another option can be using a double overhand noose instead of an 8 or bowline. The noose can be cinched tightly against the biner to prevent the rope from sliding up the gate and catching the locking barrel/nut. If you've put an AZTEK together, it's the same at the end of the travel restrict or personal end.
    Last edited by EricUlner; 08-02-2012 at 04:43 PM. Reason: typo

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    Quote Originally Posted by bottrigg View Post
    Great topic. Thanks for being honest and sharing your experience. Great comments above. I will add a few more. I would consider upgrading your belay station to a technique that passes the belay compentance test. With a rescue sized load the munter is not consistent. Mike Gibbs from Rigging for Rescue performed loads of drop tests with the munter. Very frightening data for people still using this belay technique on rescue sized loads. Also its bad form to run your belay through a AHD, especially an arial device. If at all possible run your belay on the ground, or over the bridge railing in your photo. Many will disagree with that opinion, but if you had a mainline failure and caught the load with your arial the forces would be way over your working limits. It's not so much tip load as what you putting on the fulcrum. With out knowing your arial extension in the photo, I'm guessing you could have as much as a 6:1 of the tip load down at the fulcrum. With slack in the belay this would be thousands of pounds in a dynamic situation. I know many will disagree, but there are plenty of ladder failure caused by this type of rigging. Just Food for thought. But like someone said above, you guys got the job done and everyone went home.
    Always a consideration, indeed. My assumption was single person load in Collin's scenario. My other assumption here was that perhaps Collin didn't want a belay rope flopping and smacking around on the rocky slope above people below. And if the embankment angle of repose were 45 degrees, having the belay rope in the high directional would reduce the package's pendulum hit with gusto into the rocky embankment.

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    Thanks everyone for the suggestions, exactly the discussion I was hoping for. Some follow ups and replys

    1. Eric, your absolutely right about the pulley for the belay redirect...i know better than that
    2. 300 pound load= 220lb: Patient, 60lb: stokes, 20 lb: stokes rigging and rope weight (approx)
    3.Great point about the belay connection to the bull-ring. We've all seen that crossload occur, especially with the Monster SMC XL Steelies we run on our rig
    4. Ill respectfully disagree with running the belay anywhere but through AHD. With the distance the load away from the bridge, a mainline failure would have resulted in a seriously nasty swing and left the pt. in the drink. Much rather have the hit on the aerial. Does anyone out there actually have a history on aerial failures caused by rope operations? You would think the manufacturer would discourage this type of operation if we were failing their ladders in this manner
    Last edited by cm41683; 08-02-2012 at 10:08 PM.

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    Quote Originally Posted by cm41683 View Post

    2. 300 pound load= 220lb: Patient, 60lb: stokes, 20 lb: stokes rigging and rope weight (approx)
    The steel version of the Titan basket by Traverse Rescue is 31 pounds. My team has the split apart version of same. Not much weight difference between the two. Hence my guesstimate of potential 270 lb patient. Not much weight to speak of in our bridle of 8mm Purcells at the 4 corners of the basket and the set of 4s in between the foot Purcells and the double long tail bowline. Definitely nowhere near 20 lb of basket rigging. I'd say roughly 36 pounds or so total.

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    Adding a few more,

    Noticed in the discussion that we might be mixing up load terms. Rescue is the old Light load (in accordance to the NFPA geniuses that change things), and General is still General (or two person loads).

    The litter attendant was brought up, unless you have an edge transition issue or a patient that you are pushing fluids/maintaining airway/etc.. I would shy away from it. They were using tag lines, and for that application I like it.

    Eric... your knowledge ability to convey the science of rope work is amazing. It is nothing that most (I hope) aren’t already aware of, just appreciate your ability to put it into sentence form.

    Also with using a beiner on the high help belay instead of a pulley... the beiner will add additional friction, which is your friend on a belay system. Don't really want to risk shock loading a pulley if it is avoidable.

    Great topic.
    ~Drew
    Firefighter/EMT/Technical Rescue
    USAR TF Rescue Specialist

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    FL, you're too kind.

    By the way, I looked up the weight on the steel split apart Titan. It weighs 36 lb., 5 more than the one-piece. Pretty handy though on the hike into the woods. 2 people can each carry a half basket.

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    Quote Originally Posted by EricUlner View Post
    FL, you're too kind.

    By the way, I looked up the weight on the steel split apart Titan. It weighs 36 lb., 5 more than the one-piece. Pretty handy though on the hike into the woods. 2 people can each carry a half basket.
    Heck, some chain saws weigh that much with fuel, those wildland guys are animals (Meant in a good way).

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    Eric... your knowledge ability to convey the science of rope work is amazing. It is nothing that most (I hope) aren’t already aware of, just appreciate your ability to put it into sentence form.
    I agree, and might I add I think you both bring a lot of helpful info for us new guys. I for one have learned much using this forum, and furthermore you have enhanced my ability to use my new knowledge to do more refined searches on Google for my self study.

    Thanks guys

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    Quote Originally Posted by cm41683 View Post
    Thanks everyone for the suggestions, exactly the discussion I was hoping for. Some follow ups and replys

    1. Eric, your absolutely right about the pulley for the belay redirect...i know better than that
    2. 300 pound load= 220lb: Patient, 60lb: stokes, 20 lb: stokes rigging and rope weight (approx)
    3.Great point about the belay connection to the bull-ring. We've all seen that crossload occur, especially with the Monster SMC XL Steelies we run on our rig
    4. Ill respectfully disagree with running the belay anywhere but through AHD. With the distance the load away from the bridge, a mainline failure would have resulted in a seriously nasty swing and left the pt. in the drink. Much rather have the hit on the aerial. Does anyone out there actually have a history on aerial failures caused by rope operations? You would think the manufacturer would discourage this type of operation if we were failing their ladders in this manner
    No problem. You have good reasons for rigging the way you did. I was just pointing out the hazards of dynamic loading of an aerial device. Your manufacturer would and does discourage this type of operation. If you call them up and ask if it's ok to run a belay rope through the aerial which might cause you to exceed your SWL they would say no. If you started throwing out numbers like 2000lbs at the tip and 10,000lbs at the fulcrum they would say hell no. FEMA put out a study a while back on aerial ladder failures. Two of these failures were due to rigging through the tip. This was an older study and the trucks are built stronger now. I should have said that there is a long history of aerial failures due to exceeding the SWL - not specifically rigging induced. I didn't mean to never run through AHD. It's just that if something goes really bad you can fail and aerial really easy. Pat Rhodes is trying to address some of these issues in his rigging courses by illustrating the effects of tip loads on the fulcrum of aerial devices at different extensions. I just bring this up as a discussion topic. Many departments rig both lines under the basket without issue. I just don't think they really have a good understanding of the working loads they are placing on the aerial. Which is strange because we worry about tip loading with people, ice, wind and water. But enough about that. Stay safe.

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