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Collapse Danger Zone For Aerial Streams
When a fire occurs in a multi-story building and there is danger of wall collapse, the incident commander and fire officers sometimes overestimate the capabilities of the aerial platform stream and underestimate the dangers to firefighters operating in the bucket of the aerial device. In some instances, we withdraw the ground firefighting streams away from a potential wall collapse danger, then let firefighters extend the tip of the aerial platform close to an unstable wall to extinguish fire. Sometimes, the aerial platform bucket enters the same collapse danger zone from which the ground forces are withdrawn from. This strategy is unsafe.
In recent years, an increasing number of building collapses have seriously injured firefighters operating in the buckets of aerial platforms. One reason for this increase in firefighters in the bucket being caught by wall collapse is the “arc” of a falling wall. The collapse danger zone for an aerial stream will vary from the collapse danger zone for a ground stream because of this arcing. When a wall collapses at a 90-degree angle, there is an outward arcing of the falling wall that could strike the bucket of an extended aerial platform.
All parts of an aerial platform or ladder truck must be positioned outside the collapse zone. This includes the truck and the bucket of the extended boom. To accomplish this, the apparatus must be positioned in the street outside the collapse danger zone and the raised aerial ladder, platform bucket or snorkel nozzle should never enter inside the arcing path of the unstable wall. When an aerial stream is operating and there is no danger of collapse, the tip of the aerial device may be placed as close to the building as possible.
Flanking a Fire
When a tall structure is involved with fire and there is danger of a wall collapsing, ordering a collapse zone could require firefighters to be positioned too far away. The hose streams do not reach the fire. For example, during a fire inside a church that is 80 to 100 feet in height, a collapse zone this distance would require ground and aerial streams to be operated 80 to 100 feet away to avoid falling walls. This would be ineffective. To counter this problem, a fire officer may position ground streams in a “flanking” position. To accomplish this task, an aerial platform would be placed in front of adjoining buildings, on one or two sides of the burning building, away from the unstable wall. The aerial stream’s range and effectiveness will be reduced, but the safety of the firefighters will be ensured, even if the unstable wall falls outward beyond the collapse danger zone.
Corner Safe Areas
Another safety procedure for protecting firefighters on aerial ladders using master streams is to use the corner safe areas around a burning building for placement and operation. When we look at a burning church from a bird’s-eye view, and imagine the collapse of all four walls of the structure, we see there are four areas where there are fewer bricks. They are the four corner areas around the building. These corner areas around a burning building provide the best chance of survival when walls collapse.
When setting up a fire operation at a fully involved church fire, or at any high-rise building that may collapse, these four corner areas around the structure are where the incident commander should consider positioning master streams. Because if all the walls collapsed outward simultaneously (which is unlikely) or one at a time, firefighters will have the best chance of survival in these four corner areas around the structure.
• The most effective method of extinguishing a building fire is by an interior attack. At some fires, however, due to the area of flames, the high flammability of contents or combustible nature of the structure itself, an outside attack using master streams must be the strategy. Master-stream operations at rapidly spreading fire can be extremely dangerous – collapse, explosion, downed overhead electric wires and radiated heat are some risks. At a rapidly spreading fire, apparatus initially positioned at hydrants or with ladders raised may have to be hastily repositioned away from the building to avoid these deadly events.