Part D Avalanche Rescue

1. General

During avalanche rescues, military operations differ slightly from civilian operations due to the number of personnel involved in the climbing parties, and the immediate available personnel left at the avalanche site. In civilian rescues only one or two surviving personnel are available due to small climbing parties. Therefore, the odds of recovering a live victim in military operations are higher than those in a civilian rescue attempt. Before undertaking glacial operations, it is mandatory to organize rescue teams to ensure they are self-sufficient, equipped with life support equipment, and prepared to conduct extended operations. All team members must be trained in probing, transceiver use, first aid, and digging.

Survival margin; phases of rescue operations; immediate action; follow-up; evacuation; methodology of locating victims; probable locations; and probing are rescue procedures that all members of the climbing party should be familiar with. They are discussed as follows:

• Survival Margin. If a climber is caught by an avalanche, prompt and organized rescue operations offer the only hope of rescue. Persons have survived avalanche burial for hours (Figure 1-12). Usually the victims are either killed instantly by crushing, or die within a short period from exposure, shock, and suffocation. Suffocation is the most important item since one hour is the average survival limit.

Snow is porous and contains enough air to support life, but not consciousness. About 50 percent of the victims buried in an avalanche suffocate in less than an hour. The chances of survival decrease with time; if the victim is recovered within 15 minutes, he has a 75 percent chance of survival; 15 to 30 minutes, 50 percent chance of survival; 30 to 45 minutes, 25 percent chance of survival; and 45 to 100 minutes, less than 25 percent chance of survival.

Snow inhalation is the main cause of death. Rescue operations are designed to get the victim out within one hour. Since special circumstances could prolong the life of the victim, rescue operations should continue for at least 24 hours.

2. Phases of Rescue Operations

The object of a rescue action is speed. Equipment and manpower must be assembled as quickly as possible at the avalanche site. Regardless of the rescue plan, exact preparation and organization are needed for any operation that presupposes a live rescue rather than recovery of a dead victim.

To achieve this goal, a three-stage rescue operation is organized:

• Immediate action by personnel remaining at the avalanche site.

• Follow-up by an alert rescue unit on call at the parent organization.

• Immediate Action. Surviving members of the unit are organized into the first rescue team at the avalanche site, and immediately start rescue operations.

The main factors in a successful rescue operation are the ability to be well-organized and to act immediately. The leader of this rescue team must decide if a follow-up rescue party and other help are needed; if so, it is requested by the quickest means. If avalanche dogs can be located, they should be brought to the accident site by helicopter with their trainers.

Random probing begins where there are indications of the location of the victim. If no indications are found, the random probing starts in likely locations such as obstructions in the slide path caused by trees, boulders, or transitions. The tip and edges of the slide are also searched. A human body is bulky and is apt to be thrown toward the surface or sides.

If the victim is found unconscious, first aid (artificial respiration) must be administered at once. Hot liquids and warm sleeping bags should be available for conscious victims. The alert rescue team reinforces the first rescue team.

• Follow-Up. The follow-up rescue party on duty is alerted, issued special equipment and provided transportation.

This party is dispatched under command of the most experienced officer or NCO, and should consist of one squad or one platoon and medical personnel. It should leave within 15 minutes after receiving the alert and be lightly equipped—speed is the first consideration.

The strength of the alert rescue party is that they are an on-call, trained unit, and are small enough to get ready and move out rapidly. If the area to be searched is extensive, a second or follow-up party must be sent to the accident scene as a reinforcement. The second or follow-up party should move out from one-half to one hour after the avalanche. It carries a complete set of equipment including probes, shovels, 200-pound sled, radio, rations, and other required items.

• Evacuation. Avalanche victims who are rescued alive must be evacuated under the care of medical personnel by the fastest means available. The evacuation should be accomplished by helicopter if possible.

• Methods of Locating Victims. Search operations must optimize the victim's chance for survival. A slow and thorough search would probably guarantee finding the victim, but the chances of finding him alive would be remote.

The following techniques increase the probability of effecting a live rescue:

• Before entering the avalanche track, the starting zones above should be checked to ensure that no more avalanches will run on that same track. It may be necessary to blast other starting zones before it is safe for a large party to work on the avalanche deposit.

• Once the safety of the rescuers is ensured, the party begins by establishing from witnesses where the victim was located just before the avalanche release. It then determines the point where the victim disappeared. Making use of this and any other information, a probable victim trajectory line can be established leading to high-priority search areas. A rapid systematic check is made of the avalanche debris surface, marking all clues.

• A probe is usually started at the runout point of the avalanche. If justified by visible signs of equipment or avalanche cord, an initial random probe can be made of high-priority regions. If not justified, a coarse probe can be made of all likely burial areas. The coarse probe is repeated as long as a live rescue remains possible. The fine probe is repeated only when the possibility of a live rescue is improbable.

• Probable Locations. A moving avalanche resembles a fluid. A human body with a higher density than the flowing snow would be expected to sink deeper and deeper into the avalanche. Many factors obscure this statement. Turbulence, terrain, and the victim's own efforts to surface himself all interact to determine the final burial position. Study of a large number of case histories leads to the following conclusions:

• Most buried victims are carried to the place of greatest deposition, usually the toe of the slide. If two points of the victim's trajectory can be established, a high probability exists that the victim is near the downhill flow line, passing through these two points (Figure 1-13).

f JyV^r^T of victim

Figure 1-13. Probable Location Established by Trajectory.

• Any terrain feature that catches and holds avalanche debris might also catch a victim (Figure 1-14).

• If an avalanche follows a wandering gulley, all bends that show debris are likely burial spots. The likelihood of a victim being buried in a particular bend is proportional to the amount of debris deposited there (Figure 1-15).

• Vegetation, rocks, and other obstacles act as snares. The victim tends to be retained above the obstacle. An obstacle may simply delay the victim's motion, leading to final burial downstream from the obstacle.

Figure 1-14. Effect of Terrain on Probable Location

• Maximum speed of the flowing snow occurs at the avalanche center. Friction reduces flow velocity along the edges. The closer the victim's trajectory is to the center of the slide, the greater his burial depth.

• Efforts of the victim to extricate himself by vigorous motion and "swimming" minimize burial depth. Conversely, the limp body of an unconscious victim is likely to be buried deeper.

Exceptions to the above are possible. The victim may have been hurled away from the avalanche by wind blast. A search of the surrounding terrain is advisable if a large, violent avalanche occurs.

Avalanche Probing

• Probing. Probing involves simple equipment that can be operated by personnel who do not have previous training. However, to ensure proper execution of the probe line, the search leader must know this technique. This method is not as commonly used now that trained avalanche dogs and beacons are used in civilian operations, but since they are not readily available to military units, its discussion is necessary.

Figure 1-15. Probable Locations in a Wandering Gulley

Probe poles. Rigid steel tubing about 1.25 cm (1/2 inch) in diameter is recommended for the main probe pole, and lengths of 3 to 4 meters (9 to 13 feet) are best. Longer poles are harder to manage especially in a high wind. Standardizing the length of poles in a unit should be required. When the poles are of equal length, it is obvious when one probe in the line is stopped by an obstruction.

Although the rigid steel probe poles are preferred, sectional poles should be carried by all units habitually operating in avalanche areas. This allows units to begin probing immediately. In the absence of probe poles, initial probing attempts can be started using ski poles in two methods: the ski pole can be reversed, probing with the wrist strap down; or the basket can be removed (the preferred method) so that the point is down. This method allows the ski pole to penetrate the snow more easily than in the first method.

Proper precautions should prevent the probes from icing due to large temperature variations. Probes should be kept moving in and out of the snow, and ski poles should be waxed. Probes should not be left fully inserted in snow because they will freeze in position and be difficult to extract.

For the probing operation to be effective, probing lines must be orderly and properly spaced. To ensure systematic and orderly probing, the number of personnel for each line should be between 20 and 30. The number of men in the line is dictated by the width of the area to be probed. A string line must be used to keep the probe lines aligned.

The probe line maintains a steady advance upslope. Advancing uphill automatically helps set the pace and permits easy probing to the full length of the probe. Probing does not come to a halt when a possible contact is made; the probe is left in contact and the line continues. A shovel crew follows up on the strike by digging down along the pole. Extra probes are carried by the shovel crew to replace those left in contact. This plan of operation is especially important when more than one victim is buried.

When a body is encountered, it is obvious to the probing personnel. This is easily recognizable in soft snow but not in hard compacted snow. A common problem is encountering debris within the snow that can be mistaken for the victim. The only positive check is by digging.

Techniques. There are two techniques within this method: coarse and fine probing. The effect of these two probing techniques can be compared by examining the relation of sampling (probe insertion) intervals to the projected area of the human body. The result is that the coarse probe technique has a 76 percent chance of locating a victim on a given pass, while the fine probe has a 100 percent chance of locating a victim.

Coarse Probing. This technique implies a wider spacing of probe pole insertions with emphasis on speed. It is used during initial phases of search when live recovery is expected. The coarse probe involves the following:

• Probers are spaced along a line 75 cm (30 inches) center to center. A distance of 50 cm (20 inches) is straddled, leaving 25 cm (10 inches) between the toes of adjacent probers (Figure 1-16).

• A single probe pole insertion is made at the center of the straddled span.

• When signalled from the probe line leader, the group advances 60 cm (24 inches) and repeats the single probe.

• Three signals are used for the complete sequence: DOWN PROBE, UP PROBE, and ONE STEP FORWARD MARCH. By adhering to these commands, the leader can observe the probe line when the probes are down, and he can instantly spot a high probe, which might indicate a possible location for the victim.

It is important that the signals be adjusted to a rhythmic pace set by the leader. Strict discipline and firm, clear commands are essential for efficient probing. The probers work silently.

Method Snow Probing Avalanche Rescue

Fine Probing. This technique involves close-spaced probing with emphasis on thoroughness. Fine probing is the concluding measure that usually finds the victim (dead or alive). The fine probe involves the following:

• Probers are spaced the same as for the coarse probe.

• Each man probes in front of his left foot, then in the center of his straddled position, and finally in front of his right foot.

• When signalled from the probe line leader, the line advances 30 cm (12 inches) and repeats the probing sequence (Figure 1-17). Each probe is 30 cm (12 inches) from the adjacent one.

The fine probe functions best when each probe pole insertion and extraction is done on command.

• Good discipline and coordinated probing is more necessary than with the coarse probe. Careless or irregular probing can negate the advantages of fine probing. Use of a string line to align the probers is especially important with the fine probe. The three insertions are made along a string line, which is then moved ahead 30 cm (12 inches).

Shovel Crews and Trenching. Shovel crews are organized to assist the probers, relieving them at intervals and digging in likely areas. They should be prevented from haphazard digging that wastes energy. Crews move on line behind the probers, watching for probes that are not moving in the avalanche debris. Digging goes on while the probing continues.

Fine probing should not exceed three to four hours. If this is unsuccessful, the slide must be trenched by the reinforcing elements.

Trenches are dug parallel to the contour down to ground level or to undisturbed snow at intervals of 2 meters (6.4 inches). Digging begins at the tip of the slide and proceeds uphill. It is best to space the shovel teams along one trench with frequent intervals. Snow from one trench can be thrown into another just completed.

Fine Probing Avalanche

If trenching is necessary, the operation ceases to be an emergency. Trenching should be performed only if the unit/command requires it. Trenching recovers the remains; however, the dangers inherent at the avalanche site plus the exceptional effort it requires should be considered, along with the ability to recover the remains after the spring or summer thaw.

If trenching is necessary, the operation ceases to be an emergency. Trenching should be performed only if the unit/command requires it. Trenching recovers the remains; however, the dangers inherent at the avalanche site plus the exceptional effort it requires should be considered, along with the ability to recover the remains after the spring or summer thaw.

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