Difference between revisions of "Appendix F: Rescue Sled Handling"

Latest revision as of 22:56, 2 December 2009

[edit] Rescue Sleds

TBSP uses three types of rescue sleds:

1. Commercial rescue sleds, which can carry both equipment and patients. With these sleds we can carry a full range of first-aid equipment, including a backboard;
2. Patrol manufactured portable sleds carried by patrollers which weigh 2 - 4 lbs. exclusive of ropes;
3. Brooks Range Rescue Sleds (1.5 pounds); and
4. Improvised sleds are constructed with materials available at the injury site. This type is used only in cases of multiple injury or failure of the portable sled, but patrollers must be able to construct such a sled in case such an emergency arises.

The portable sled can be completely constructed using materials in the Portable Sled Module and the patient's skis. The improvised sled can be completely constructed using materials in the Repair Module, the patient's skis and poles and two detachable shovel handles.

[edit] Sled Hauling

This section contains diagrams regarding sled handling. The leader should give all commands for starting, stopping, slowing, and changing of others' position. The followers should communicate any problems to the eleader, including difficulty with the terrain, the need to slow down, or the need to halt the sled if someone falls. This article discusses TBSP rope rescue systems used to raise and lower loaded sleds on steep slopes. Patrollers and candidates must understand the material depicted in this appendix. Sled construction and handling will be thoroughly covered during field training.

Moving Toboggan Belay, Wide Trail 

             Flat/Rolling                   /                  Uphill                  /                  Downhill

Moving Tobbogan Belay, Narrow Trail 

             Flat/Rolling             /                        Uphill                   /                 Downhill

Anchored Belay (downhill) 

                            Hand Belay     /                                                   Carabiner Brake

[edit] LOW-ANGLE ROPE-RESCUE SYSTEMS FOR USE ON SNOW

This document discusses the construction of low-angle (15° to 40°) rope-rescue systems used on snow. It is not intended to describe either equipment or procedures for low-angle rescue off snow or high-angle rescue. The systems discussed in this document have been designed for backcountry use, where equipment weight is a significant consideration.

[edit] Rescue Team

The TBSP rescue team should include three or four patrollers, allocated as follows:

• Two main-line tenders (haulers)
• One belay-line tender (optional)
• One rescue-sled / patient tender

This discussion assumes that each member of the rescue team carries the following personal equipment:

• One 20' length of red 1' webbing
• One 20' length of 6mm static cord
• One 5mm prusik loop
• One descender
• Two locking carabiners

[edit] Terminology

Images missing! Please upload images from the PDF Patrol Report

Horizontal 3-to-1 Raising System

a two-anchor point, three-pulley system that permits hauling perpendicular to the fall line; the Z is rigged perpendicular to the fall line

Vertical 3-to-1 Raising System

a single-anchor point, three pulley system that permits hauling perpendicular or parallel to the fall line; the Z is rigged parallel to the fall line

1-to-1 Lowering System

a system that permits lowering of the rescue sled down the fall line

Anchor Point

the tree or other immovable object to which the system is anchored

Anchor Webbing

1' webbing in 12' (yellow) and 15' (blue) lengths

Anchor

the combination of anchor point and anchor webbing to which a system is attached

Anchor Pulley

a pulley attached to an anchor

Prusik-Minding Pulley (PMP) 

an optional type of anchor pulley attached to the first anchor point that prevents the safety prusiks from being swallowed by the pulley

Haul Pulley 

a pulley attached to a haul prusik loop

Safety Prusik 

a prusik hitch that acts as a rope stopper in the event of system failure

Haul Prusik 

a prusik hitch that pulls on the haul rope during raising

Descender

a belay device such as a brake bar rack, Sticht plate, rescue-: or ATC that is used to control the rope during lowering

Load-Releasing System

a system consisting of three carabiners and a 1' x 48: sewn webbing sling attached to the tandem safety prusiks to facilitate changing the direction of a system

Mariner's Knot

the knot used in the load-releasing system

Lock-Off Carabiner

a carabiner used to lock the free end of the mariner:s knot to the anchor carabiner

[edit] TBSP Rope-Rescue Module

The TBSP Rope-Rescue Module contains all equipment required to construct a horizontal or vertical 3:1 raising system or a 1:1 lowering system (except belay lines and associated equipment), and also supports reversing the systems:

• One 50 m x 8mm static rope
• Three 5mm static cord prusik loops
• Two 12' lengths of yellow 1' webbing
• One 15' length of blue 1' webbing
• One 1' x 48' sewn runner sling or equivalent for Mariner's Knot
• Nine locking carabiners
• Two standard pulleys
• One prusik-minding pulley and One 5/8 inch stainless steel washer
• One brake-bar rack descender

[edit] Anchors

1. Use appropriate anchor points - trees, BFRs, buried skis or snow anchors.
2. Attach one yellow anchor webbing and one blue anchor webbing to the first anchor point, and, if using a horizontal 3:1 system, attach the remaining yellow anchor webbing to the second anchor point.
3. Ski or snow anchors should be placed with regard to the forces that will be exerted on them
4. Buried skis can be used as snow anchors in all but the hardest snow, and are always available. If pickets are used in hard snow they should be rigged in tandem, three being better than two.

[edit] Deciding Which Raising System to Use

This decision will normally be driven by three factors: (1) the length of the rescue rope, (2) the distance between the patient and the first anchor point and (3) the availability of natural anchor points. For purposes of this discussion we will assume a rescue rope length of 150 feet.

1. If the patient is located more than 50 feet below the first anchor point, a horizontal system should be used. This is because it takes three equal spans of rope to rig the vertical system, a maximum of 50 feet each. A horizontal system using two horizontal rope spans of 30 feet each leaves 90 feet vertically between the first anchor point and the patient. A vertical system of 50 feet or less will not require resetting; a horizontal system of 90 feet (vertical) will require several horizontal resettings.
2. If there is a natural anchor point immediately above the patient, a vertical system is preferred (assuming an acceptable vertical distance from patient to anchor point) because it only requires one anchor point and does not have to be reset. However, if you have to resort to a snow anchor point (e.g., buried skis) it is preferable to use a two-anchor horizontal system for reduced anchor strain and redundancy.
3. The first anchor point should always be immediately above the patient in the fall line to avoid raising or lowering across the fall line. Therefore, unless you have a tree or other natural anchor immediately above the patient, you should use a two-anchor point horizontal system with buried skis or other snow anchor as the first anchor point. When employing a horizontal system try to use at least one tree or other natural anchor point.

[edit] Belay Lines and Safety Prusiks

A separate belay line should be used whenever conditions dictate. Such conditions include steep slopes, situations where the rescue sled must be carried over rock, and any situation in which main line anchors are considered tenuous. If a main line fails, the forces exerted can exceed the restraining ability of the tandem safety prusiks, resulting in total system failure. Belay lines tend to carry part of the load, especially when lowering, thus reducing strain on the main line while providing necessary safety redundancy. Figures 3 and 5 show systems rigged with belay lines, which should have independent anchor points.

The TBSP separate Belay Module contains the following:

• One 150 foot x 8mm static rope
• Two 5mm static cord prusik loops
• One 12' length of yellow 1' webbing
• One 15' length of blue 1' webbing
• One 1' x 48' sewn runner sling
• Seven locking carabiners
• One prusik-minding pulley
• One brake-bar rack descender

Tandem safety prusiks provide an excellent safety margin. A single safety prusik can be used, but there is a danger that the single prusik loop might break, or that the single prusik hitch might not lock during a system failure. With tandem safety prusiks the load on the second prusik hitch to lock during a system failure is greatly reduced, thus assuring a much safer system. Note that in lowering mode the tandem safety prusiks must be tended by an additional patroller. Although not ideal, a brake bar rack can be operated with one hand, leaving the other free to mind the safety prusiks. If a separate belay line is used in lowering mode it should also be rigged with tandem safety prusiks operated by an additional patroller. All TBSP main and belay lines are pre-rigged with tandem safety prusiks. The following table represents an unscientific attempt to gauge the relative degrees of safety inherent in various systems.

It is not meant to suggest that any particular system should be used.

[edit] Reversing System from Raising to Lowering

1. Extend tandem safety prusiks to maximum lengths
2. Slowly release tension on haul rope until tandem safety prusiks engage
3. Remove all pulleys and haul prusik(s) and store carefully
4. Substitute a descender for the first anchor pulley
5. Rig descender and lock off
6. Disengage mariner's knot and slowly transfer tension from tandem safety prusiks to lowering rope
7. Reset tandem safety prusiks, then retie mariner's knot
8. Unlock descender and give command 'ready to lower'

Reversing System from Lowering to Raising

1. Lock off descender
2. Extend tandem safety prusiks to maximum lengths
3. Unlock descender and gently transfer weight to tandem safety prusiks
4. Replace descender with anchor pulley; add other pulleys and haul prusiks as system requires
5. Rig raising system
6. Give command 'ready to raise'

[edit] Notes on System Failure

When a low-angle rope-rescue system fails it is almost always because of operator error. Common mistakes include:

• poorly tied anchor (water) knots (check all knots before operating system)
• poorly tied double-fisherman knots on prusik loops (check all knots before operating system)
• poorly tied or dressed prusik hitches (check all knots before operating system; use three wraps)
• failure to lock carabiners (check all carabiners before operating system)
• poor belaying technique
• improper rigging of system

[edit] Patient Packaging

The patient must be attached to the sled and to the main and belay lines. To accomplish this use an improvised webbing seat harness (diaper sling) as described in MT&R, p. 66, Fig. 42a, then tie the harness into the sled and rescue lines with the extra webbing or rope. If possible, the patient should also be provided with a helmet.

[edit] Communications

• Belay commands are given (1) if a separate belay line is used in raising mode, (2) during lowering, (3) when locking off to switch direction of system or (4) when resetting in raising mode

Tahoe Backcountry Ski Patrol Manual