Getting “Over the Edge”: readers respond
Editor`s note: Following is a series of letters received from readers regarding “Getting Over the Edge,” by Kenneth J. Brennan, which appeared in the December 1994 issue of Fire Engineering, and Brennan`s responses. The letters and responses have been condensed–from the perspective of questions raised and author`s response–for clarity and brevity.
….What is safe for a “climbing load” may not be safe for a “rescue load.” We must define what our loads are; for example, a climbing load is considered to be 175 pounds, a rescue load 450 pounds, and an extreme rescue load 600 pounds–except for NFPA standards, which consider a rescue load to be 600 pounds….
When performing “emergency egress” procedures, the rescuer needs to get out as quickly as possible [to avoid a potentially lethal hazard such as flashover or structure collapse]. When weighing these risks, the rope simply becomes a mode of transportation to decrease the force of impact with the ground, thus minimizing injury. In this situation, it is better to have multiple fractures than be dead. Does the same rule hold true while performing a rescue? I tend to believe not. We as rescuers should have the time–without compromising patient care–to properly and safely rig the rope systems, which would include marginal, bomb-proof, equalizing anchors; edge protection; appropriate belay techniques; etc.
When discussing equalizing anchors, the question of efficiency arises. When we tested a simple equalizing anchor similar to the one pictured in the article, our results demonstrated that, when the anchor is loaded, the carabiner becomes locked or snagged in the webbing and one of the legs of the webbing becomes slacked (usually the one on the same side as the load) and the other leg begins to take more of the load. I would like to know if this problem has occurred with Mr. Brennan`s equalizing anchor.
The author spoke about low and high anchor points but did not address the advantages and disadvantages of each. An anchor can blow, and has blown, because the connection was high as opposed to low and load amplification has occurred. But, to tie low may increase the difficulty in getting over the 90-degree edge.
At the end of the article, the author discusses using a belay technique. What belay device or technique does he use? I would have liked to have seen these techniques included in the pictures to provide a better overall understanding of the systems he recommends. Some controversy has arisen with regard to certain belay techniques, for example, the Munter Hitch vs. tandem prussik belay. One is not better than the other, given its proper use and setting. The Munter Hitch is ideal when belaying a climbing load; that was the purpose for which it was designed. Unfortunately, it was taken out of that category and used in rescue loads. Does that mean that if you must perform a rescue and you do not have prussik cord and an L. R. hitch available, you do not belay? Certainly not! As rescuers, we must become flexible and have backup options.
The bottom line on belay techniques is to know your parameters. You could body belay a climbing load with little if any discomfort, but could you body belay a rescue load? certainly not without having the same effect as liposuction.
Keep this in mind; the need again arises for your rescue team to become familiar with various belay techniques, and this comes with training.
Another point of discussion is the use of “double and triple backup anchors.” I strongly disagree with this practice based on the following rationale: Using one length of rope and doubling it to increase the safety parameters–okay two ropes instead of one might double your safety by making one pseudo-thick rope. Disadvantages include the possibility that if one rope is severed, the second rope running alongside and parallel could also be severed. Another option is to use one full length of rope (which would allow longer descents and ascents without bends in the line) and having an entirely separate line as a belay system. I understand the author`s reasoning in using a doubled rope, but then why don`t we also double our primary anchor and our carabiners, etc.?
Another issue to be considered is the fall factor with these backup systems. How much distance would our load drop before our second anchor catches our load? If we are using similar diameter ropes, anchors, and carabiners and a force is absorbed that blows out the first anchor, would the pound force (lbF) increase when applied to the second anchor?
In the “triple backup anchor,” two prussik hitches were used in the system. What were their lengths and diameters? How many wraps are the prussiks? With what type of knots were the prussiks attached to the working line? The rope that attaches to the prussiks appears to be one rope, so if the prussiks do catch, do they bypass the second anchor? Is the falling load held by only one rope should the prussiks catch the load?
Also, regarding the use of a tower ladder with live loads, has the author ever been concerned with the possibility of injury occurring if the person becomes snagged or the rope accidentally is caught while the ladder is moving? What would give first–the tower ladder, the person (load), or the rope? We have not practiced in depth with tower ladders, but our experience has been to lock-out and tag-out anytime we have live loads on booms or hydraulic equipment.
….I believe there is a significant need for research through testing equipment and techniques in this area. So seldom are questions asked without fear and hesitation of offending the person(s). I look forward to continue to read these interesting articles.
Eric H. Martin
Senior Instructor
Over the Edge, Inc.
Plainfield, New Jersey
Kenneth J. Brennan responds: Disseminating information and receiving feedback are crucial to learning. The information in my “rope articles” is presented in a very basic format and is intended to stimulate thought and discussion. The resulting meaningful interaction makes the fire service the great profession it is–and our job safer.
The emphasis of the article was on operating in the emergency egress mode on the fireground. I wanted to cover a skill area that isn`t talked about much but can cause many problems. Many out there know how to rappel; however, they don`t know how to set up in the given situations. That`s why “Getting Over the Edge” was developed–yes, you can rappel, but can you clear the edge? While being developed, it was suggested that a review of anchoring be included, and it was.
The four common anchoring scenarios were presented in a basic and short format. Like many other instructors, I have preferences as to which to use. The equalizing anchor, presented in its simple form, when loaded will be difficult to move. When you get to where you`re going to operate and you actually load the system, there isn`t too much movement. The point of that illustration is to try to equally divide the weight between two or more objects and emphasize the safety loop and carabiner placement should you lose an anchor point. You must make sure the system you build is sufficient for the anticipated loads. Short lengths of rescue rope tied appropriately can be used in place of webbing.
The tie-high and tie-low anchor points denote their placement with respect to the angle of departure of the rappeller. Normal anchor placement would dictate wrapping the base of an object, as it usually is the strongest place. However, we must constantly be aware that alternative anchors are available and press them into service at a moment`s notice. The cities of the northeast are comprised of downtowns built of type III ordinary and type IV heavy timber construction. Egressing these types of buildings can present a challenge when looking for anchors. Tie-high situations dictate looking at pipes in the ceiling. Numerous renovations usually provide an abundance of overhead pipes to which the multiple anchor principle can be applied.
Tie-low situations dictate using anchor points from the waistline to the floor level. Connecting to substantial pipes or structural components is the norm. Breaking through gypsum board walls and wrapping around a couple of studs is an option. The bottom line is you take what`s available and make the decision to use it or not. Mr. Martin is absolutely correct when he says that a tie low may increase difficulty in getting over the 90-degree edge. That`s why the article was developed to educate others to handle that situation.
The issues of single- and double-rope techniques are addressed in the next letter.
The question of the advantages and disadvantages of using a tower ladder is a good one. This type of apparatus offers a movable “platform” from which to operate, particularly when no high vantage points are available. Several options can be used; the article depicted one of them. First and foremost, the operation shows the rope being packed into the rope bag. This technique is foreign to many fire departments in this situation. My colleagues in law en-forcement and military special operations employ this technique in a similar way. They pack their ropes this way so as not to announce their presence when making an assault. In the rescue business, this technique allows personnel to be boomed over to the target for rapid insertion technique (RIT) evolutions. As shown, once over the drop zone, release the rope bag, ensuring that it makes it to the ground, and start the descent. This eliminates snagging and injury. Common sense dictates correct spotting, illumination of the area, radio communication, and supervision. Obviously, when you recover the tower and move back to the starting or nested position, you have to make sure the hanging ropes are secure and don`t get snagged.
