by Andy Selters
Because ice and especially snow are such variable mediums, there's no hard and fast rule as to how many anchors are enough for a rescue. In general, trust your intuition: if you're not sure, add more anchors!
Figure 3.12 Improperly equalized anchors:broad angle multiplies force on anchor
Figure 3.13 Basic pulley system
THE BASICS OF PULLEY SYSTEMS
It takes a lot of force to haul someone out of a crevasse. Friction of the rope running over the crevasse lip increases the resistance, so that hauling even a partner with no pack generally takes two to five times as much force as a strong climber can generate. Therefore, all but the largest parties have to increase their hauling force by using a pulley system. In a manner analogous to low gears that enable a bicyclist to climb a hill, pulley systems distribute a load and allow even a single person to haul another out of a crevasse.
The basic block-and-tackle pulley system is shown in figure 3.13; the rope is anchored at A, and runs through a pulley, B, which is connected directly to the load. When the end of the rope, C, is pulled, the pulley (and the load as well) moves only half as far as the rope end at C. This means that the work is halved, and the pulley and load receive twice the original force. Another way to look at it is to realize that looping the rope through the pulley back to the anchor generates a second force. This is because the length of rope A-B (between the anchor and the pulley) effectively pulls on the load, too.
This simple system is known as the C-pulley system, for the single curve in the rope. Theoretically, it gives a 2-to-l mechanical advantage, although even with a good rescue pulley that dissipates only 10 percent to friction, the actual multiplying force will be 1.8 to 1. Also, maximum efficiency comes only when the pulling force at C is in line with the pulley and the anchor—that is, when lines A-B and B-C are very close together For clarity, figure 3.13 has been drawn with the rope coming out from the pulley to point C at an angle, but if the force is applied to the side like this, essentially pulling partly away from the system, the force applied at C is less than doubled.
CREVASSE RESCUE PROCEDURES
The general procedures for rescuing a partner from a crevasse are as follows:
Stop the fall.
Anchor the rope, leaving enough slack to reach the victim.
Check the victim, and decide on a rescue method. Generally speaking, the first choice is to have the victim ascend out, as previously described; the second choice is to haul him or her out.
Prepare the crevasse lip.
Either assist the victim to ascend over the lip, or set up a hauling system.
Haul the victim out, if necessary.
With this sequence in mind, we can detail the elements of crevasse rescue.
HOLDING A FALL
Let's return to the well-prepared three-person rope team traveling together on a glacier Poof! One of the members disappears. The adjacent partner must hold the fall.
As stated previously, if the rope is tight and fairly perpendicular to the crevasse, most snowbridge collapses can be held by simply standing firm and leaning hard against the pull from the fallen partner If the rope does not come taut immediately−that is, if the victim is stopped by the snow-bridge or narrow walls before the weight of the fall bears onto the partner−the partner should retreat from the crevasse and pull the rope taut. If the force of the fall pulls an adjacent member off his or her feet, then that partner must work into the ice-ax arrest position, as should the next member down the rope. As discussed in chapter 2, the nightmare of being pulled toward an abyss, digging and kicking for every ounce of ice-ax arrest grip, is rare, but it can happen.
Crevasse falls generally end in a split second. In minor “punch-ins” where half the victim's body is still on the surface, then “rescue” is easy. Partners on the surface stand firm with the rope tight, and with this help the victim probably can just struggle out. If the victim is in too far to climb out right away or is stuck, then the surface members should anchor the rope, the first step in a “genuine” rescue.
ANCHORING THE ROPE
Besides keeping the victim from falling any farther anchoring the rope allows surface members to be belayed out to the crevasse edge to assist or check the victim; it enables the victim to ascend out on the rope, if possible; and it allows the surface members to set up a hauling system.
The first and third criteria make it important to anchor the rope not at its end, but in the midsection, leaving enough slack to reach the victim. This is where the proper spacing of members discussed in chapter 2 becomes critical. Assuming a three-person rope team has an end member fall, here's the procedure for anchoring the rope:
The middle member holds the rope taut, either in ice-ax arrest or by leaning against the pull.
The free member on the end of the rope comes down to “below” the middle partner coming down the rope with a self-belay.
At a reasonable distance below the middle person (but not close to the crevasse), the free person sets an equalized anchor pair, preferably at least l0 to l5 feet below the middle person, to leave plenty of free rope above the anchor to reach the victim.
The free person then loops a three-wrap prusik (or sets an ascender) onto the taut rope leading to the victim, and clips this into the anchor. He then slides this anchoring prusik down the rope until it's fully stretched against the anchor.
Now the middle person cautiously moves toward the crevasse, letting the victim's weight go onto the anchor With the victim solidly anchored, both members can escape from the rope, although they must be wary of other crevasses.
The next step is to assess the victim's condition and position, for these things will determine the nature of the rescue. The victim and the surface members might be able to shout back and forth, but if the victim is any distance down, a surface member will have to go to the crevasse edge to establish communication.
CHECKING THE VICTIM
It should go without saying that anyone venturing near a crevasse into which someone has just fallen needs a belay. More than one would-be rescuer has unwittingly fallen to their death.
Surface members can use another rope or the slack rope “above” the anchor to belay the person going out to check the victim. One surface member can tie off to the anchor and belay another, or a solitary rescuer can go to the lip on a self-belay. If but one rope is available, using a self-belay allows the free end to be sent into the crevasse, either to haul the victim's pack or to rappel on. While approaching the lip, however, it doesn't hurt to back up the self-belay with a figure-eight knot clipped into the harness from slightly farther down the rope. The member going out can also carry one or preferably two ice axes and extra prusiks and runners.
Whatever the belay, it's wise to approach the crevasse lip some distance to the side of where the rope disappears, to avoid putting weight on the unstable lip directly above the victim, as it may break further and cause injury. As the surface member approaches the edge, getting down on hands and knees puts less stress on the unstable lip. Then the rescuer can either set the self-belay (and back that up by clipping into the rope at that point) or instruct the belayer to hold firm while he or she leans out to talk with the victim and assess the situation.
Ideally, the victim is unharmed and either is preparing to ascend the rope or is already doing so. If the victim needs a pack hauled, the free end of the rope can be sent down for this. The person at the lip should wait there to assist the victim over that last desperate overhang. One way to help is to set a prusik or ascender above the lip and use this to lower a ladder of runners for the victim to climb up. Another is simply to reach down with a tethered ice ax for the victim to grab and heave up on.
If a victim cannot ascend out because of injury, partial burial, wedging, or any other reason, then the surface members must haul their partner out. In this case getting the victim past the overhanging remnants of the failed snowbridge can be the hardest part of the task. Preparing for this problem deserves a discussion of its own.
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Figure 3.14 Padding a crevasse lip (note self-belay and backup)
PREPARING CREVASSE LIPS
During a crevasse fall the rope often cuts deeply into the lip, and during hauling the rope saws into it even deeper As a result, while being hauled the victim rises into the expanse of the overhang, confronting it as a huge barrier. It can be very important for the members at the edge to mitigate this, with either of a couple of different tricks.
First of all, you can slide an ice-ax shaft under the rope and push the rope out to the lip. If the victim is hanging free, you won't be able to push the ax out any farther than the rope already runs. But if there's little or no tension on the rope you should push the ax out as far as the lip will assuredly bear
If the edge slopes one way or another, then during hauling the rope will slide down the ax shaft. To keep it from sliding off the shaft, place the ax with the adz skyward and on the downhill side of the slope. This way the rope will slide down the shaft to the crotch of the adz and remain there. (Some axes have a sharp edge along the adz-shaft joint and should not be used this way.)
Finally, you should tether the ice-ax “pad” to another ax or anchor of some sort away from the lip (see fig. 3.14), because if the ax falls it will invariably fall on the victim. If there's no ax to spare, then a thick cluster of tent poles, a pack, or other items can serve as pads or pad anchors. Ski poles can anchor a pad, but they aren't strong enough to serve as a pad themselves, and if they break their ragged broken edges can slice a rope.
If the rope has already cut too deeply into the lip, the team might have to take a more drastic measure of sending down a “fresh” rope over a prepared and prepadded edge. This is discussed in the next chapter.
With the lip prepared one way or another the final step before setting up a hauling system is to make sure the anchor system is adequate. Most hauling systems can potentially increase the force on the anchor just as they multiply the force on their load, because they depend on creating a tension between anchor and load. The force on the hauling anchor will equal the weight of the victim and gear, plus the friction and resistance at the crevasse lip. Over-stressing the anchor is especially likely if the victim comes up against the crevasse lip and the haulers continue to pull with all their might; with a pulley system they can generate a tremendous force on both anchor and victim. Therefore, any anchor to be hauled on should be “bombproof.”
SETTING UP A HAULING SYSTEM
Once the victim is attached by a prusik to a bombproof anchor you're ready to set up a hauling system. The “tried-and-true” and easiest system to set up is the three-to-one or Z-system. The Z-system runs the rope through a pulley at the anchor then up and back through a second (“tractor”) pulley attached to the main rope. Essentially it's a C-system except that instead of tying into the anchor the rope runs through the anchor and down to the load. When hauling on this system, the haulers pull in 3 feet of rope for every foot that the victim rises; therefore they have to pull with a force equal to only one-third of the victim's weight, not counting friction. Set up the Z-system like this:
Figure 3.15a Z-system for hauling: thread rope through belay plate (autoblock), then pulley, then clip pulley to anchor (note: prusik is already taut to anchor carabiner, holding weight of victim)
Figure 3.15b Z-system for hauling: wrap prusik on loaded line; then thread slack through pulley and clip to prusik
Figure 3.15c Z-system for hauling: ready to haul
Above the anchor prusik (that is, on the side away from the victim), push a loop of rope through a belay device. During hauling, the belay device keeps the anchor prusik from dragging into the pulley placed at the anchor, and it is often called an “autoblock.”
Immediately above the autoblock, thread the rope through a pulley, and clip this pulley into the anchor with a new carabiner (see fig. 3.15a). This prusik-autoblock-pulley arrangement at the anchor can be called a “ratchet,” allowing the haulers to pull the rope through the system, but stopping the rope from sliding back—and the victim from falling back.
From the ratchet, loop the rope back parallel to itself as far up toward the crevasse as it's safe to go, and thread the slack line through another pulley.
Wrap and set a prusik around the main strand.
Clip the new pulley into the new prusik (see fig. 3.15b), and run the slack line back to the anchor. This second prusik-pulley arrangement is the “tractor:” This is the line you haul with, and you're now ready to haul (see fig. 3.15).
RATCHETS
There are a number of other methods for creating a ratchet at the anchor in a hauling system, all with advantages and disadvantages. Among the useful ones are the Garda hitch, the Penberthy knot, and the French braid. I won't attempt to describe these alternatives, but for those who might be introduced to them I will compare their important features.
The Garda hitch has the advantage of offering an immediate brake with no slack. However; because no pulley is used, it generates added friction. Also, its simple but crucial construction is easy to forget.
The Penberthy knot and the French braid both offer fairly quick brakes, but only slightly or no better than a prusik with an auto-block. Depending on the pulley and perlon used and the tying method, these two ratchet systems can jam into the pulley, adding significant friction or dangerously stopping the pulley.
Gear-minded climbers can buy “prusik-minding” pulleys with flanges for keeping a prusik or related knot away from the wheel, an integral autoblock. Most function okay, but still need tending. Also available are pulleys with an ascender-like cam that serves as a ratchet. Although manufacturers warn that these cams damage the rope in shock-load falls, they seem safe and convenient for crevasse rescue hauling.
Because the prusik-autoblock setup offers excellent performance using gear generally carried anyway, for most teams it remains the recommended method.
IMPROVISATION
It was the first working day of an expedition to climb Nun in Kashmir Our team and a handful of porters had crossed some snowfields to cache our supplies where we thought the glacier began. One of the porters punched a foot through where there'd been no sign of a crevasse, so we knew the warm conditions were dangerous.
As the last four of us were returning to base camp, a Japanese climber trying an adjacent peak yelled down from the edge of another glacier. One of his buddies had fallen into a crevasse. He was three meters down. Could we help? Most of our gear was hours away at our cache, but we just happened to have with us one harness, four carabiners, two ascenders, two axes and some webbing. We had no rope, no anchors, and no pulleys.
We followed the panicked Japanese leader to the crevasse. There was no sign of his partner for he had fallen much deeper than three meters, without a rope or harness. The leader said he had a rope and tent cached about 20 minutes away. These items were the only hope. I followed their footsteps, probing constantly and gasping as I occasionally found hollowness. But in not quite an hour I returned with the rope and tent poles. We buried the poles for an anchor and backed that up with a buried ax. Giving the Japanese leader our ascenders and spare harness, we lowered him into the crevasse, insisting on double assurance that he knew how to ascend back out.
A long time went by with no word from below. We yelled down, but the leader's English had crumbled into incomprehensible murmurs. By then a squall came in, and with snow collecting on us we started shivering and thinking about the approaching night. I decided to haul out the leader, and if the original victim was a goner, so be it. With two carabiners and a runner in a kleimheist knot, I built an inefficient Z-system. With our first heave, such a blood-curdling wail erupted out of the crevasse that we figured the rope was somehow wrapped around a tender organ. We stopped hauling and went back to waiting.
Another 20 minutes went by, and I decided, organs or no, we had to pull this guy out and get back to camp. We hauled, the screams resumed, and we kept hauling. We had no ratchet at the anchor so when it was time to reset the kl
eimheist I pinched the rope bend at the anchor carabiner with all my might, while another slid the tractor back toward the crevasse. Still bellowing, the leader reached the surface, the ascenders clamped on the rope but unused.
“Your buddy?” we asked.
“Yes. Ready for rescue.”
We switched to the other end of the rope, and hauled out the original victim. He was cold, and the long slide down a narrow chimney had beaten up his hand, but other than that he was fine.
After 10 years of climbing and half as many guiding, I looked at the various levels of competence around me, and I was glad I had been given the caution, and learned the skills, to avoid such situations.
HAULING
Hauling itself is a straightforward matter of pulling on the free strand of the rope, in line with the anchor and victim. Added security and power can come from the haulers tying into the rope and pulling from their harnesses, rather than just holding the rope with their hands.
During hauling, the tractor pulley moves toward the ratchet. Depending on how far the victim needs to be hauled and how far you set the tractor pulley out from the anchor, you'll probably bring this tractor up to the anchor At this point you need to carefully let the victim's weight back onto the ratchet prusik, perhaps stretching out this prusik manually to make doubly sure that it immediately grabs.
Here it also doesn't hurt to check that the ratchet prusik isn't getting significantly abraded from the haul rope. In rare cases, mainly on an icy ablation zone where grit can coat the rope, the ratchet prusik can abrade quickly. Once the victim's weight is securely held by the ratchet prusik, you can slide the tractor back down the taut primary rope as far as is practical, and then resume hauling.