All right, this is the rescue scenario we're doing right now is called a twin-tension skate block. We have a victim up top, once again, he is a compliant climber. He's either fallen on his fall arrest device or sitting in his work positioning device, unable to get out of it, and he's unable to get down to the ground. There could be many scenarios that we could use this operation for.
In our skate block system what we're using is we're doing it with one person trying to be as clean and efficient as possible with a small group of highly trained individuals. We have one rescuer going up. He is bite carrying both of his ropes, his main and his belay, up to the top above our victim, once again, maintaining 100% fall protection using Y lanyards and his work positioner as he gets to up top.
As he bypasses the victim, once again, he is assessing the victim as he goes, seeing what exactly is wrong with him, checking his harness before we make any connections to it, before we actually put any pressure on it to lower him down to the ground.
Once he assesses the victim, he goes past him. He's going to make his anchors. When he's making his anchors up top, he's trying to get to that 6' - 10' range. It's kind of the sweet zone up top above our victim.
Both are going to be at the exact same spot, twin-tensioned again, they're both going to be, trying to mirror each other, if you will, up top and on the ground. He's going to make his connection points around six feet at least above our victim.
Two anchor slings, then he's going to go back down, and he's going to make his connection point to our victim. He's going to connect into our victim. On this one again, he has a tower harness on. He only has a sternal or a dorsal D-ring. The way he's positioned right now, he's going to connect both into a sternal D-ring. Once he makes his connections to the sternal D-ring, he's in a work position, and then he's good to go.
He's going to sit back, communicate with the ground. Then, the ground's going to take up tension. The ground's going to take up tension on our victim, and then our rescuer is able to disconnect whatever our victim's hanging off of and to bring him down to the ground.
When he does make those connections, when he comes back down, there's three different ways that we can lift that victim up.
- There's an inline system. If we're using Petzl IDs, or we're using MPDs, what we can do is we can make a three-to-one haul system on either one or both of them, lift our victim up just enough to get him off, disconnect, switch back over to our lower and lower him down to the ground.
- The other one we can do is we can do a dynamic anchor on it. A dynamic anchor is similar to what we were showing for some of our tower control scenarios earlier is having that mini four-to-one (4:1) system in between our anchor and the extension control device. In between the ID that we have and the anchors, we're going to have a four-to-one system, so we can take that and collapse it down. If you guys have IDs or MPDs, a lot of times that isn't really necessary. What it is, is you can still use it for that obviously. Where it really comes into play, where it really shines I guess, is if you're using racks. If you have a rack somewhere up top on a tower, or you're using a rack down at your anchor on the ground, having that dynamic system in between gives you that adjustability to move it in and out.
- Then, the last one, the third one that we can use is vectoring the lines up. Vectoring the lines is basically you're using your angles to your advantage. You can use one or two guys, you can come up, grab your lines once you tension them up a little bit. Just walk those lines down, hold them down, bring them down, it's going to raise our victim up.
There's two different ways you can do that. You can have it where our lines are coming straight down to their anchor, or you can have what we call a true vector field where we come down to what we call a butt-block and then coming back down to an anchor. It gives you a whole big vector field where you can just walk it down. That's going to give us our biggest raise.
But, sometimes, we're not going to want to do that. A lot of times, we won't do that because our height of the structure, the height of the structure and the length of our ropes. We might need to use all the rope we have. Those are the ways that we're going to be able to lift our victim up, once he makes those connection points.
Why Use Two Tension or Twin Tension Systems in Tower Rescue
One of the reasons why we do the twin-tension skate block, we do a twin-tension skate block versus a traditional, what I call a traditional skate block ... A traditional skate block is one skate block line and then one belay line up top on a structure. The reason why we don't do that, we defer to the twin-tension system is because of the swing fall.
If, say, we're up 180 feet up in structure, we're doing a skate block system out, and he's coming 40, 50 feet off the structure, if that mainline fails, even with the belay up top, what's going to happen is he's going to swing either into the ground or into the structure. That's why we always defer to whenever possible is try and do a twin-tension system. When we're doing a twin-tension system, we have both lines trying to share the load, 50-50, 60-40, and then, obviously, if one line fails, the other one's going to grab it.
Now, our victim is hooked up, he's ready to go. Our rescuers are ready to go. The guys on the ground are taking up the slack into the systems. Once they have the slack out of the system, that's when our rescuer's going to disconnect his devices that he's on. He wouldn't want to do it beforehand, because there's still a lot of slack built into the system prior to him disconnecting him. He waits until all the slack is out of the system, then he disconnects him from his work positioning device and from his fall arrest device.
All right, so once he's up, and he's off his system, now, the guys on the ground own the victim, and they're going to lower him down to the ground. The nice thing about the skate block system is it's self-equalizing with the load we have on it. It minimizes our load at our anchor, at both our anchors, on the ground and up at top on the tower.
Peace on your Days...