It's time to debunk some of the popular misconceptions that exist concerning rope-rescue operations.
Rope-rescue operations fall into the high-risk/low-frequency category of incidents for most fire departments. Because of their rarity, training for them probably does not receive the priority it should, especially when the potential complexities of the rescue operation and the hazards to response personnel and the victim are considered.
Equipment and methods for high-angle rescue continue to improve and evolve. Rescue incidents are evaluated, research and testing is performed, papers are written, and presentations are made. The consensus standards, such as ASTM and NFPA, that establish performance levels for training and equipment are reviewed and updated every five years. If your department has a rope-rescue protocol in place — or has not developed one, but has the potential for high-angle rescue incident — you also should consider reviewing it on a regular basis. Here are some common misconceptions that are worth a second look as part of that review process.
Misconception No. 1: Rescue hardware for the fire service is required to be made from steel
While the fire service traditionally has used steel carabiners — and sometimes, but not always, steel descenders, anchor plates and other hardware — it never has been required by a standard. There are several reasons why some departments thought steel was required, but testing has proved that none of those reasons are valid.
Strength: Hardware currently is classified in NFPA 1983, Life Safety Rope and Equipment for Emergency Services, as G (general use), L (light use) or E (escape), depending upon its intended use. General use has the highest performance requirement, which in the current edition is 40kN (8992 lbf.) for carabiners. There are aluminum-alloy carabiners that easily meet this standard, and which offer the added advantage of weighing half as much as their steel counterparts. That can be a savings of several pounds or more for the firefighter climbing up a structure to perform a rescue. Using lighter equipment will reduce fatigue and allow your firefighters to carry more equipment. It also could reduce the number of personnel required to perform the rescue operation.
Durability: It was said that if you dropped aluminum hardware it would develop microscopic fractures that could later fail under load. When several manufacturers of rescue carabiners were asked if this was true, the answer was "it isn't an issue with the alloys used today."
When a piece of hardware is dropped accidentally in one of our classes, we immediately pull it out of service and log the distance it fell, the surface upon which it impacted, the ambient temperature and other data. Later we destructively test (break) those dropped items. We have yet to see one fail below specification.
Upon hearing that account, a major manufacturer of carabiners conducted its own tests, also under controlled conditions. They dropped dozens of aluminum carabiners from 27 and 54 feet onto concrete and asphalt paving, with similar results. How the carabiner lands — which is beyond our control — affects the outcome of the test, but the fact remains that overall there was no significant loss of strength due to the drops. Of course, no one is suggesting that you pre-drop your rescue hardware. Any hardware — aluminum or steel — that has been subjected to a significant impact should be taken out of service.
Temperature: Aluminum begins to corrode and weaken rapidly above a temperature range of 190°C to 204°C (375°F to 400°F), but who is performing rescue operations in those conditions? Is that really a concern? Most firefighter emergency-escape anchors and descent devices intended for exposure to fireground temperatures are made of aluminum.
Corrosion: Aluminum does corrode when exposed to certain chemicals and steel will rust. If you are working in corrosive atmospheric conditions, you should consider using stainless-steel hardware. If the conditions are that corrosive, you also should be cognizant of what those chemicals are doing to your rope, your protective clothing and your firefighters.
Misconception No. 2: Safety knots are required
This is a subject on which we at CMC Rescue have turned 180 degrees. In the earlier editions of the CMC Rope Rescue Manual, we included the statement, "A knot is not a knot until it is tied off." Other rope-rescue manuals have similar statements. After many years of observation and study we have abandoned that position and in the fourth edition of our manual the above statement is absent. What changed our position from this previously accepted practice?
First, consider the safety knots themselves. Safety knots have varied over the years as rescue ropes have evolved. Thirty-five years ago, when three-strand Goldline was the state-of-the-art rope, the half hitch was considered the proper safety knot — if one was used at all. It was not particularly effective and usually untied with very little movement of the rope, but it did provide a sense of security. Eventually, the overhand knot became the accepted safety knot, because it was thought to be more secure than the half hitch. But when the more-flexible kernmantle ropes moved from climbing and caving into rescue — replacing Goldline rope, which hardened as it was used — the overhand knot was viewed as insecure and the double-overhand knot became the standard.
Today we teach the "figure eight" family of knots for several reasons. One is that, when properly tightened, such knots stay tied, which renders the safety knot unnecessary. Furthermore, the figure-eight knots are self-tightening and as such do not work loose with use.
If your protocol calls for other knots in your rope systems, the bowline for example, you should still tie a safety knot. Regardless of whether the bowline is weighted, it tends to come undone.
During use, we observed that the tie-off knots often became untied. When that happens, all they really provided was a length of "tail" hanging out of the primary knot. That tail would provide a safety margin should the knot start to slip or untie.
The other thing we noticed was that during both training and actual rescue operations, persons not totally proficient with knots tended to underestimate the amount of rope needed to tie the knot so that enough rope would remain to tie the safety knot. Sometimes it would take two or three attempts to get the safety knot right, which slowed the rigging process. While we do not advocate a reduction in safety in circumstances where it is difficult or time-consuming to achieve, this discovery caused us to reexamine the need for the safety knot.
Webbing is light and flexible, so it often is the material of choice for tying anchors. The knot most commonly used to tie the ends of the webbing together to form a loop is the water knot (sometimes called the ring bend). Traditionally, the webbing tails were secured with an overhand knot — either around the standing part of the web or by itself at the end of the tail — in order to keep the end of the webbing from slipping through the knot itself.
A very thorough study was presented at the International Technical Rescue Symposium on the subject of water knots used to tie loops from tubular webbing. The major factor contributing to knot failures was the number of loading and unloading cycles to which the knot was subjected, not the amount of force. In most cases, the knot eventually will fail due to the tails slipping through. The study showed that it would take hundreds of loading/unloading cycles, many times greater than what would be encountered in a training day or rescue operation, for that to happen.
The presence of a tie-off or safety knot did little to change that, as the safety knot often became untied early in the tests. In fact, the length of the tail was the more important factor. Consequently, we now advocate a tail length of 3 inches (8 cm) after the knot is pulled snug, for knots tied with webbing. For knots tied with rope, we advocate a 6-inch (15 cm) tail length after the knot is pulled snug. An easy way to remember that is as follows: a hand-width for webbing and a hand-length for rope.
Misconception No. 3: Load-sharing multipoint anchor systems are better than load-distributing versions, or vice versa
NFPA 1006, Technical Rescuer Professional Qualifications, requires that a technical rescuer conducting a rope rescue be able to construct a multipoint anchor system, but the standard does not specify which one. That is fine, but what do you require from your personnel — load-sharing or self-equalizing? The advantages and disadvantages of each type of system currently is a topic of debate within the rope-rescue community.
In the rugged terrain encountered by climbers and cavers, anchor points are not always available, so they would place artificial anchors using chocks, pitons and ice screws. When these anchor points were questionable, they would connect them together via a load-distributing anchor system to self-equalize the load between the points, and also to make the anchor system non-directional. When such climbers and cavers became wilderness rescuers, they continued to use the load-distributing anchor systems.
As rescue rope developed for technical rescue and the fire service, rescuers found that with the larger-diameter ropes, the friction in the load-distributing anchor systems prevented shifting to such degree that the load between the anchor points was equal. However, there was concern that if one of the individual anchor points failed, the resulting slack would allow the anchor system to extend. This would result in an impact load on the system, with the possibility of additional individual points failing in a cascade effect.
This limitation is shared by load-sharing and load-distributing anchors; the difference between them lies in the respective methods of tying them together, and there are advantages and disadvantages to each. Load-sharing works well as long as the system is built correctly with proper-length "legs." But if the load shifts from side to side, an individual anchor point potentially could become overloaded and fail, which would compromise the system. Using a load-distributing anchor system partially corrects the shifting-load problem, but how evenly it distributes the load to each anchor point is impacted by many factors, such as the material used, the way it is constructed and the location of knots in the system.
The ideal solution for fire-rescue situations would be to find a "bombproof" anchor point. It would be faster to construct, use less hardware and be safer in the long run.
Misconception No. 4: We are required to use a safety factor of 15:1
One of the more controversial issues in rope rescue concerns safety factors. A question you should ask is, "what is the safety factor to which we should try to construct our systems?" Further, how was that number determined? Is it even possible?
We recommend that as a part of rope-rescue training, a detailed analysis be conducted of the systems used. Examine the force that is on each piece of equipment, both during normal operations and when there is a failure. That analysis must include more than the minimum breaking strength of each piece of hardware. It should consider force multipliers, such as the angle of the rope through pulleys as they are loaded, and the loads placed on individual components as systems are modified during the course of the rescue evolution. It also should consider "what ifs," such as when a litter is caught on an obstruction and the haul team fails to stop in time.
There is no perfect or standard answer. For example, some agencies use higher safety factors for training than for rescues. The reasoning is that they have all the time necessary for redundancy and the fact that the systems will be subjected to repetitive loading, as they are used throughout the training day. They might use NFPA G-rated equipment for training or urban rescue operations, and L-rated gear for operations in wilderness areas where carrying heavier rope and hardware might not be an option. That might reduce the safety factor to some degree, but still would allow a perfectly safe rescue operation.
Industrial rigging equipment usually is designed with a 5:1 safety factor. That also is a ratio that many mountain rescue teams use for their systems. Many fire agencies state that they use a 10:1 ratio. Those agencies that say they use a 15:1 ratio should re-check their analysis, since that figure rarely is possible. Consider that the NFPA 1983 performance requirement for a general-use, 12.5 mm (H-inch) rope tops out at 15 times the design requirement — without any knots.
The safety factor is important when selecting the systems to be used by your agency and in evaluating each individual rope-rescue operation, but safety does not stop there. Remember that a higher number might not guarantee a safer rescue operation when knots are not tied correctly, anchor selection is poor or edge protection is missing and a rope is cut. The human element is just as critical as the technical.
Rope-rescue education developed as a grassroots discipline. Instructors learned from other instructors, some of whom also were rescuers. Much was disseminated by word of mouth, and catchy "rules" thought up by one instructor became industry standards a few years later. As the discipline developed with the testing of equipment and procedures, and the emergence of industry seminars where the leading experts would evaluate what we were teaching, it was determined that some of the so-called truisms were not supported by either rope-rescue science or field experience. Hopefully, this article has removed some of the cloudy thinking around these common misconceptions.
John McKently is the director of the CMC Rescue School and also teaches the rope rescue, confined-space entry and rescue, mine rescue, and specialized rope rescue classes as a lead instructor. He also teaches search management for the California Emergency Management Agency. He has over 35 years experience in technical rescue with the Montrose Search and Rescue Team of the Los Angeles County Sheriff's Department. McKently is a member of several ASTM and NFPA standards committees relating to search and rescue. He was a member of the Board of Directors of the National Association of Search and Rescue and served as the treasurer of that organization for four years.
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