Hybrid Counterweight System for Glacier Fumarole Rescue Applications

Transcription

1 Hybrid Counterweight System for Glacier Fumarole Rescue Applications Presented to: International Technical Rescue Symposium November 1 thru 4, 2018 Portland, Oregon USA Presented by: Eddy Cartaya National Cave Rescue Commission Portland Mountain Rescue Redmond, Oregon USA Glaciercaveeddy@gmail.com Glacier caves, and specifically fumarole glacier caves, are fairly rare phenomenon in mountain rescue. As such, there is typically little preplanning or training customized to rescue scenarios in these areas. Fumarole caves are by definition formed by volcanic steam and gases emanating from a subglacial vent, which then melt a vertical conduit upward until it opens at the surface, or is collapsed into by an unwary mountain traveler. Fumarole caves often have toxic levels of magmatic gases in them, which can quickly incapacitate a climber. For normal crevasse rescue techniques, if the party is already roped up, retrieval can be done using existing crevasse rescue methods, and no one has to enter the suspect hole. In some areas, however, fumarole caves occur on fairly gentle slopes, or at the base of an exposed but easy pitch, where climbers are unroped. In this case, a fall into a fumarole cave creates a unique, high urgency, rescue situation, which has the potential to multiply patients if rescuers are subsequently exposed to bad air. This proposal was developed specifically based on a unique problem in the crater of Mt Hood, where a glacial fumarole opens up each year near the base of the final chute to obtain the summit ridge. Many climbers do this route unroped, so when a fall occurs, the patient can slide down into the ant-lion shaped fumarole beneath them. This can result in either traumatic injury, exposure to toxic gases, or both, with it being hard to discern which by casual, top-side observation, especially if the patient is unresponsive. This is an urgent small party rescue situation, akin to an avalanche burial or crevasse fall. Exposure to the conditions (burial, hypothermia, corked body in ice, exposure to bad air, etc.) of the incident are likely to be more lethal in short order than the trauma generated by the fall into the feature. A full call out rescue response is not likely to make it in time in these cases, thus a solution must be executed by those on scene using only the gear they have with them. Various counterweight systems have been in use for a long time in cave rescue, arborist work, and mountain rescue. This paper outlines a hybrid counterweight solution based on small party rescue tactics, designed for a ready team of 3 or 4, or a small group of adjacent climbers. It is a niche rig, in that its characteristics are specifically designed to mitigate the unique hazards and threats to this very specific rescue scenario.a single climber trapped at the bottom of a glacial fumarole, unroped, with the threat of toxic air and a very short response time. Barring one or more of these aggravating factors, many other less complex and traditional systems could be used. This is a specialized rig proposal for a very specialized problem. 1

2 Risk Assessment and Decision Making: This is a technical paper on a rigging system, not a book on mountain rescue decision making. As such, I will not go in depth into this much broader component. HOWEVER, since many aspects of this hybrid rig were designed to deal with aspects of this unique environment, and influence a GO decision versus a wait for full rescue decision, I want to very briefly address a few considerations. There are many human element factors, and other technical considerations involved with this scenario. Gas monitors, sulfur masks, mini-escape rebreathers, etc. are all devices that a mountain rescue ready team / hasty team in such a response area should have at their disposal, but may not. Certainly other climbers / bystanders are not likely to have them. Visual assessment of the patient, avalanche conditions, ability to monitor the air at different levels in the hole, snow conditions for anchors, time the patient has been exposed, ability to communicate, all play into the complex human decision process that must occur prior to deploying a human being into a high risk environment...if only for a short time. Risk assessment based on exposure times, probability of success based on triage, etc. are complex topics that merit a lot more discussion than this paper provides. No one wants to watch someone die, but it is worse to create a situation where 2 or more people die because of a hasty decision driven by heroic ambition...also referred to as tombstone courage. Mountain rescue knows to stop and assess snow conditions, post look outs, and check for hang fire before rushing into an avalanche burial...even though it means the buried patient must endure a few more minutes of pain and respiratory trauma. Someone corked in a crevasse unroped also merits risk analysis, as adding another patient to an ice crack and crevice situation more than doubles the complexity. Certainly someone in a hole with potential bad air merits risk analysis, as toxic magmatic gases are invisible, often odorless, can mimic altitude illness, and can hang close to the ground, not affecting a rescuer until they reach the patient, or bend over to clip them in. Indeed, some gases form a dank or very distinct planar boundary, where the air is 100% clear at waist level, but deadly below the knees. These are burning car rescue scenarios. Someone is trapped in a lethal environment and has only a little time (potentially) to live. A decision must be made to risk another life to perform the extrication...or not. These are personal, on the spot decisions, often driven by emotion and drama. Urban responders are more likely to dive into a burning car extrication due to the horrid and dramatic nature of such a death, whereas a quiet or unseen killer such as hypothermia or bad air tends to spur more caution and reservation. If a decision is made to go for a rapid extrication, the intent is not to render care in the adverse environment, or to even see to the patient s comfort, but to simply remove the patient from the deadly environment to a safer place where a proper assessment and stabilization can then be performed. Someone shot in a city park 50 meters from a road will be examined, stabilized, packaged, and moved to an ambulance in due time. A soldier shot 50 meters from cover, who is still taking rounds, will be rapidly dragged from the kill zone...by his feet if need be, and THEN patient assessment and care performed where no further harm can occur. Quick removal of the patient and responder from the deadly environment that threatens BOTH people is a common characteristic of high urgency rescues. As such, this proposal will not encourage patient care or packaging at the bottom of a gas fumarole, and will advocate a simple, single rope solution set up in such a way as to manage the rescue load in the safest manner possible.but NOT with the same safety factor as you would expect in a full call out rescue team set up.and hour or two later. 2

3 This paper will focus only on the merits and characteristics of the rescue rig, assuming that all other considerations and human elements have been dealt with separately. This paper is not to encourage those unfamiliar with bad air rescue scenario to engage in this kind of rescue unless properly trained. The reader assumes all responsibility for their safety using this technique. Assumed Conditions of the Rescue: The lip, or approach to the vertical drop is heavily sloped...not flat. Designed for a minimal ready team of 3 trained in the rig. It is safer and more comfortable with 4. Each team member should have 1 picket and a soft interface for it. Rescuer team only has 1 rope, likely a 9mm diameter range, 40 or 50 meter length, dry line. Patient is at bottom of a 5 or 6 meter hole in the ice with an overhung (corniced) lip. Patient is not roped. Patient may not even be wearing a harness! Other climbing parties present do not have gear. Nice if they do, but system must be riggable and operational by just 3 responders with the standard glacier traverse gear / hasty team gear. No access to a rescue cache (which may be buried, frozen shut, or gone). 3 equalized snow or ice anchors support the rig. It is assumed the anchors are sound and sufficient for a 2 person load. Due to urgency, no 2nd independent system is required. (if gear and people are there to rig it quickly, by all means use it!) Benefits of Hybrid Counterweight Systems: A single rope can be used to share the load of 2 people. Smaller diameter rope is ok. Rescue load is split over 3 strands. A high SSF is maintained. Redundancy is built in via an autostop at the pick off rescuer as well as at the top station. Ideal for confined spaces or venues where there is not a lot of space at the top. The operation is vertical, and there is no top side haul operation moving linearly. Rescuer weight is being used, so there is no need for a large haul team. Ideal for hasty team / ready team response. Friction concerns are the same. In a mirrored system, 2 moving ropes go over the edge. In a counterweight system, 2 moving ropes (in opposite directions) must be dealt with. Concerns / Notes: Top side anchor must be bomber. It will have the weight of 2 people plus friction on it. To be most effective, edge friction must be managed. There are 2 moving lines going over the snow (granted one of them is flowing downward). This would also be faced with a TTRS. Lower counterweight rescuer can serve as a human bipod for the 2 moving lines, if needed. They can also act as an edge assistant when pick off rescuer returns. A lightweight monopod can help a lot here. Run the 2 moving lines of the system through the pulleys on either side of monopod. Leave the static leg on the snow. If used, it is important the pick off rescuer does not traverse left or right very much along the lip of the drop, and stay relatively directly in the fall line below the pod. The 2 moving lines must run over an ice axe or picket at the lip to prevent cut in. 3

4 As this paper discusses a proposed rig that integrates two types of counterweight techniques, a quick review of these counterweight system principles is addressed first. It is important to understand these basic building blocks in order to understand and troubleshoot the proposed hybrid system. Part 1: Diminishing Loop Concepts As the above diagram illustrates, the difference in figures A and B is simply closing the loop. In figure A, a ground hauler pulling a climber up must lift the full climber weight. The top anchor sees roughly twice the patient load. At figure B, if the rope is now handed to the climber, who then pulls themselves up, the effort needed to make the lift is now only 1/2, but the climber must climb twice the length of rope. Additionally, the load on the anchor is only the weight of the climber. This is the classic arborist, double rope technique. Figures C and D show the same concept, but now, a 2 to 1 drop loop has been integrated. In figure C, a ground based hauler must lift 1/2 the climber s weight, and pull through twice the amount of rope as the pitch is high. The anchor sees 1 1/2 the climber s weight. In figure D, the rope is now handed to the climber, who ascends it with their climbing system. By closing the loop the advantage has now gone to a 3 to 1. The climber only has to lift 1/3 their weight (plus frictional losses) but must now climb 3 times the amount of rope to make an equivalent vertical gain. The load on the anchor is again just the climber s weight same as figure B. It does not matter what mechanical advantage is rigged in a closed loop system. The load on the anchor will always be the collective load attached to the system...in this case, one person. Note that the climber operating the system in the closed loop may ascend or descend, with normal single rope technique. The system works the same. If rappelling on a 3 to 1 closed loop, as shown in figure D, the descender will only see 1/3 of the climber s weight (minus any frictional losses.) 4

5 These closed loop systems are referred to as Diminishing Loop counterweight systems. The loop is diminishing assuming you are hauling or climbing. If you are rappelling or lowering a patient down, it is effectively an expanding loop. The same physical principles apply. The classic diminishing loop set up, as used frequently in cave rescue when hauling a patient up with the rescuer, is to have the patient attached to the end of the rope (tied in, or via their climbing system), and the rescuer operating their climbing system on the other side of the counterweight line. The two subjects are connected by a tether which closes the loop. In this format, the load on the system is the collective weight of the two subjects. In Figure 2, the patient in blue (left) weighs 220 pounds and the rescuer in yellow (right) weighs 180 pounds. The collective load (shown in the circle) is 400 pounds. The anchor sees 400 pounds, no matter how the internal configuration of the diminishing loop is made. The rope between the rescuer and patient sees 1/2 the collective load, in this case, 200 pounds. As such, only 200 pounds of force is required for the rescuer to climb up with the patient, but twice as much rope must be traveled. In this format, the tether connecting the two subjects sees half the difference of the two weights. The difference here is 40 pounds, so the tether sees 20 pounds. Benefits to this format are that the rescuer and patient ride close together. The heavier of the two (patient in this case) will ride lower, tensioning the tether by half the difference in the two person s weights. The rescuer can level the two people by pulling up on the patient s side of the counterweight line 20 pounds, with their arm essentially taking the place of the tether at that moment. This is good for patient care, but perhaps not the best if the rescuer (or patient) is wearing crampons. 400 lbs 400 lbs 200 lbs 220 lbs Figure lbs 180 lbs 400 lbs An alternative format, shown in figure 3, is to have the patient hang off the rescuer by a tether, and have the loop closed at the rescuer. This is the classic arborist format as shown in figure B on the previous page. In this example, patient and rescuer weights are the same as figure 2. Note that the rope tension and anchor load are also the same. The collective load is still 400 pounds, but the tether connecting the two here is bearing the patient s weight pounds. The amount of force needed to raise the load is the same pounds, and again, twice the amount of rope will have to be traveled. 200 lbs 200 lbs In this format, the rescuer cannot level off with the patient. For an unconscious patient, this is not as good. For a conscious patient, it is sometimes preferable, especially if the Figure 4 parties are wearing crampons, as you can set the tether up to keep the patient below 180 lbs leg length. It is also good for uncooperative patients, or piggy backing the system onto a protestor s rope if using this for non-compliant removals. Figure lbs These concepts hold true for the 3 to 1 version shown in figure D on page 4. The patient can ride the system either below the rescuer (like in figure 3), or near level with the rescuer as shown in figure 2. In the case of the level tether format, the pulley for the 2 to 1 component shown in Figure C would go to the patient and the rescuer would climb the other side of the counter weight line, with the two still connected via a short tether. This set up is shown in figure 4. In both formats, the rescuer is in full control of the system. The system is reversible by the rescuer changing over from ascent to rappel or vice versa. 5

6 Climbing Counterweight System There are many versions of the rappelling and climbing counterweight systems. The rappelling counterweight system results in two additional rescuers going to the bottom of the pitch, which we do not want in this case. The climbing counterweight is also most easily operated by the two counterweight rescuers operating from the bottom of the pitch, needing no position control line for safety, but again, since we are dealing with a hole full of potential bad air, we do not wish to stage any rescuers there. Figure 5 shows the climbing counterweight system operated by two rescuers, each safetied to a static line (shown in red). One rescuer is seldom enough to outweigh the patient load plus friction, which is required to lift the patient, so two are usually needed. The safety line prevents the two rescuers, which now outweigh the load, from flying to bottom as they pull the patient up. Note that in this rig, there is no tether to the patient. A progress capture / safety prusik has been placed on the patient side of the counterweight line. This climbing counterweight technique can be applied to any counterweight situation. For example, in figure C on page 4, two counterweight rescuers could easily be on the haul side of the line instead of the one hauler shown there. The advantage of this system is that it can be operated from the top of the pitch. Drawbacks are that it is not as easily converted or changed over, and a connection to the patient must initially be made! The Hybrid If we combine the 3 to 1 diminishing loop system shown in figure D on Figure 5 page 4 with the top based climbing counterweight rig shown above, we get the rig shown in figure 6. (For the sake of clarity, the rescuers have been omitted and only the rescuer s master harness loops are shown. The patient is the figure in blue.) Upper rescuers Starting with the rigging bowline ( fat rabbit ) at the anchor focal, the leftmost strand is the static leg of the 3 to 1 diminishing loop. It goes down to the rescuer s harness and through a pulley or roller carabiner. This line will not move over the edge during the operation. Rescuer master loop The line continues back up through a progress capture and pulley at the focal (or extended forward some if using a monopod) and then back down to the rescuer s descender or climbing system. The remaining static tether coming from the anchor knot is used as the edge safety and position limiter line for the two climbing counterweight rescuers at the top. This safety tether should reach just over the lip of the drop, so the lower counterweight rescuer can assist at the lip if need be. The two counterweight rescuers at top are attached to this line via a prusik and can apply the climbing counterweight force from any point along it. The upper counterweight rescuer usually stays near the progress capture to set and release it as needed. Figure 6 6

7 Operation of the Rig 1. Build a solid load sharing anchor in the snow. Typically for a rescue load such a pick off, this will entail 3 snow pickets or 3 ice screws. Create a focal with a soft anchor interface and clip a carabiner to it. (Lacking extra software, the rope itself could be used for this if you tie long loops on the anchor side of the bowline.) 2. Tie a bowline on a bight with a forward facing loop (or equivalent) and clip to the anchor carabiner. One strand of the rope should hang just over the edge of the drop with a knot tied in it. The other strand should have enough rope to cover 3 times the distance from the anchor knot to the bottom of the drop. (For the average fumarole depth of 8 to 9 meters, a classic 40 meter rope should rig the problem. ) 3. Clip a pulley and progress capture to the forward facing loop of the knot. 4. Rescuer stands facing the anchor and routes the long side of the rope through a pulley attached to their harness. 5. Run this rope back up through the progress capture and counterweight pulley at the forward facing loop. 6. Bring rope back down to rescuer and thread in your descender (typically an ATC type device). It is advised you extend the ATC away from the rescuer with a short tether...maybe 6 inches, so it does not interfere with the pulley on their harness. 7. Rescuer attaches their upper climbing ascender to the rope above their descender. 8. Rescuer has a tether (purcell, cowstail, strap, etc.) connected to their D link or carabiner for their waist ascender, ready to attach to patient. If patient is not wearing a harness, carry a webbing loop, Alpine Bod, or other fast diaper harness with you. 9. Start to rappel in. Upper counterweight rescuer must tend the progress capture in order for pick off rescuer to descend. Lower counterweight rescuer should self-belay to edge to act as visual and voice relay. Place ice axe at edge to prevent rope cut in. 10. Once pick off rescuer touches down, they FIRST changeover to ascent! Clip in the other ascender and remove descender. If gas monitor is alarming over IDLH, (over 3% CO2 or 100PPM H2S), start out immediately. 11. Use monitor to test air at the patient level on ground. The air at your standing height might be safe, but bad at ground level. 12. THEN, bend over to clip the tether to patient harness. If patient has no harness, quickly tie a diaper seat. If patient is conscious, have THEM clip it and watch for correctness. If patient is unconscious, also add a webbing a chest harness and connect the two together. 13. Start climbing out. You will move slow, but only have to lift 1/3 the collective weight plus friction. Call up to top side and tell counterweight rescuers to start hauling as well, until you are above any suspect danks. 14. If rescuer for some reason gets into trouble, or goes unconscious prior to clipping patient, their trailing ascender will lock. Counterweight rescuers then immediately set progress capture, attach their ascender to the descending counterweight line, and start to climb in place. This will haul the pick off rescuer up via a 2 to 1 drop loop, using the rescuer s weight as counterweights. 7

8 Positive Characteristic of rig (blue crosses indicate rescuers, red star is patient) Only one responder enters the threat area Pick off responder is in control of their own descent and can stop or changeover the instant they see a need to. No delay in calling for a stop, or reliance on communication with top station., which may be compromised by wind, distance, blowing snow, etc. Responder descent has an autolock. If they are incapacitated, they stop the moment they release the upper ascender they are trailing. There is an independent autostop at the top, in the form of a prusik being tended. Responder is never off rope at any time during the extrication, and be retrieved remotely from the top at any time. This is one reason the classic diminishing loop format is not recommended here...where the rescuer and patient are on opposite sides of the counterweight line and ascend fairly level and close to each other, as per figure 2 above. Once at the bottom, the rescuer would have to disconnect the roller pulley from their harness and attach it to the patient, along with a tether. During that moment of reaching down to transfer connections, if the rescuer is incapacitated by bad air, the top rescuers would not be able to retrieve him. It is vital that the top rescuers can retrieve the in-hole personnel at ANY TIME. Responder descends slowly with the benefit of a 3 to 1 expanding loop. Slow descent is good in this scenario. If responder is dangling a gas monitor, this gives the monitor time to sample the air and time to hear an alarm. Responder changeover is nearly instant, with half their climbing system already in place, and can they can climb on their own power with a 3 to 1 benefit. Top responders are rigged and ready to serve as climbing counterweights to pull the responder, and / or patientresponder out. Since the approach to the vertical lip is heavily sloped, they can easily utilize their weight in a counterweight capacity. Climbing counterweight can function independently, or in concert with the responders climbing effort. Can be rigged with one rope and 3 anchors, as well as the SRT gear of the 3 responders. Only additional gear needed is a PMP and pruisk. Due to load being shared by 3 strands, a small diamter rope does not impact the SSF. Drawbacks / Watch out s Team must know how to set this up. It is not a traditional, or often used set up. Top anchor must be bomber. It will see a 2 person load plus friction. System efficiency suffers significantly with edge friction. While there a 3 to 1 advantage for the climber, and 2 counterweights assisting, which will likely overcome this, it is better if either a human bipod or monpod is utilized to reduce some friction. Even a small lift over the snow surface will help a great deal. 2 moving ropes travel over the edge. Edge must be protected via an ice axe or picket to prevent cut in.the same issue with any other haul system. 8