….The basic premise of Mr. Brennan`s article is that the operations discussed would be carried out in an emergency situation. As firefighters, we are predisposed to do all we can to assist those in need. We must, however, ensure that we do not become victims ourselves….Points of concern include the following:
“Anchor point(s) must be sufficient to hold at least a two-man load–rescuer and victim” (p. 42, paragraph one).
Under NFPA 1983, 1990 edition, a two-man load is defined as 600 lbs. This is the minimum safe working load for which a rescue rope must be rated; the same rope has a minimum breaking strength of 9,000 lbs. This provides a margin of safety of 15:1. An operational margin of safety is generally accepted as being 10:1 or 6,000 lbs. for a two-man load. Anchor point(s) must be capable of holding 6,000 lbs. or 10 ¥ “…a two-person load….”
Author`s note (p. 43, paragraphs two, three, and four) describes the use of multiple anchors. The importance of keeping the contained angle of the rigging setup between anchors as small as possible is touched on. The critical angle of 90 degrees is given as the ideal. For example, a 500-lb. load applied to two anchors 180 degrees apart is given. The theoretical load applied to each anchor approaches infinity as the angle approaches 180 degrees. At an angle of 120 degrees, the same 500-lb. load will exert a 500-lb. pull on both anchors, effectively eliminating any advantage gained by using a multianchor system. As the angle increases to 150 degrees, the pull on each anchor increases to 1,000 lbs. This is an unacceptable configuration.
Mr. Brennan states “…the individual using these anchoring methods may not use the traditional mountain climber`s approach with regard to keeping angles between anchors small.” On the contrary, overloading an anchor must always be avoided, and therefore rigging angles must be kept within the 90-degree or less range.
Out-a-window descent (p. 46, paragraph one). Rappelling from a window suggests that the victim is located directly below the window. If this were the case, breaking out the glass would invariably result in the victim`s being bombarded with falling shards of glass–an unacceptable situation to say the least.
The description of the operation contains the following: “Get all the glass out, and pad the edge…if you have time.” [There are] two problems with this statement: The new multipane glazed windows make it nearly impossible to remove all the glass, and rescue rope must be protected from sharp edges at all times. Ropes seldom break under rescue loads, but a loaded rope will cut like tissue if it contacts a sharp edge.
In a test carried out by our department, a 12-inch static rescue rope was loaded with 150 lbs. A sharp edge (glass) was pressed against the free hanging loaded rope. The rope was instantly severed, illustrating the importance of using adequate edge protection at all times.
A final point concerns the suggestion to throw down the rope bag before rappelling down to the victim. Two possible problems could arise, again assuming that the victim is directly below the rappeller. The victim may be hit by the rope bag as it falls to the ground, which could easily knock the victim off a ledge or swing stage. If the rope bag clears the victim, the standing line will be left hanging close to the victim. If the victim were to grab the rope as the rescuer was descending, the rescuer would be locked in place in the same manner as a bottom belay can be used to control a descent. Getting a scared and possibly injured victim to let go of that rope would likely prove impossible. To avoid both these situations, a bagged rope rappel is preferred if the victim is directly below the rescuer. By hanging the rope bag three to four feet below the rappeller, the rescuer can safely and easily approach the victim from above without endangering himself or the victim.
The author illustrates some effective operations for reaching a victim using a rappel system and states that certain safety steps should be in place before beginning a training evolution. He then states that these same safety steps can be omitted if the situation is critical. No firefighter I know would dispute the urgency of doing all you can to help a victim in imminent danger, but we must draw the line when the safety of the rescuer is jeopardized in the process. Putting two people at risk accomplishes nothing….”
Jim Andrews
Firefighter First Class
City of Nepean, Ontario, Canada
Kenneth J. Brennan responds:
Page 42, paragraph one: I stated, “Anchor point(s) must be sufficient to hold at least a two-man load, which accounts for the rescuer and the victim.” The information cited by Firefighter Andrews–the two-man load is 600 lbs., the margin of safety per NFPA 1983 is 15:1, and an operational margin of safety is generally accepted as being 10:1–is correct and reinforces information I covered in previous articles.
With regard to the area of anchoring, Andrews correctly cites the importance of keeping the angle between anchor points under 90 degrees and describes the stress placed on anchor points exceeding 180 degrees. I believe, however, that he read too much into my “undesirable” setup. Regarding the statement, “The individual using these anchoring methods may not use the traditional mountain climber`s approach with regard to keeping angles between anchors small,” nowhere did I say to exceed 90 degrees. My definition of small is 30 to 45 degrees, and if I were to increase the angles by 100 percent, it would still be 90 degrees.
Regarding the statement “Get all the glass out, and pad the edge if you have the time”….First and foremost, I said, “Get all the glass out!” If there is no glass, then you don`t have a glass problem. If you are having removal problems, then you must review basic truck company skills with your people. Many of the windows in my area are light-gauge vinyl or aluminum replacement windows. If you`re going to break out four panels of glass and cross-pieces, take out the entire window. A few well-chosen blows with a halligan by an aggressive truckie should take that assembly right out of the opening–problem solved. The technique is generally designed for egressing a structure very quickly. The items listed for edge protection are commonly available and can be used at a moment`s notice. If operating around glass or other sharp surfaces, be sure that proper edge protection is in place.
For the problem associated with rope bags and placement of rescue ropes near victims: …the things cited by Andrews can happen. My suggestion is to employ proper techniques and communication. The rescuer can use the packed rope bag technique or wall-walk over to the victim.
As for the omitting of the basic equipment and techniques if the situation is critical, the intent of that statement concerned training vs. emergency egress evolutions and SRT vs. DRT….The keys to safe operations are realistic training, close supervision, and teamwork. n
