<Previous Displaying 2/3 Page 1, 2, 3 Next>
View Article as Single page
Another result of incomplete size-ups is adopting a defensive strategy when an offensive one was possible. The fireground is ever-changing, so we should always examine our dynamic transitional posture. The following factors influence our dynamic transitional posture, requiring firefighters to take actions that may direct us into either an offensive or a defensive strategy:
- Visible fire that we must extinguish from the outside to enable us to move in on the inside.
- Visible occupants needing rescue or whose location is confirmed.
- Changes in or revealing circumstances related to structural integrity.<
- Attainable and coordinated ventilation needs.
- Personnel available on the scene.
The above items, which require actions that influence our dynamic transitional state, occur frequently on the outside of the fire structure and also carry extreme risks—not necessarily death but serious injury to firefighters who are racing against time—this is inevitable. This is why training in performing all of these actions is so very important to a fire department and its members.
As we know, visible viable occupants in need of rescue, especially at windows, take precedence over other actions that are needed at structural fires. Also at times we have to take multiple actions so we can rescue savable occupants, such as providing hoseline protection during civilian rescues. Many successful, viable rescues are possible when known occupants are at windows within reach of our ladders, especially when the interior stairs are not tenable or an interior removal is not possible. When we receive visible, credible information on the location of those in need of rescue, their survival totally depends on our ability to act quickly.
When these elements are present, ventilation and where it will be performed may increase the dangers to survivable occupants by drawing fire and smoke conditions to them. Avoid any positive-pressure ventilation (PPV), since it may diminish the survivability of occupants by forcing fire and smoke conditions into their areas. Wind direction and speed can also diminish occupant survivability. Because we cannot control the wind, fire companies must move with even greater urgency when confronting wind-driven conditions.
The transitional dynamic posture includes an aggressive attack incorporating exterior water application as quickly as possible instead of running headlong into the interior for extinguishment. When a particular volume of free-burning fire presents itself through the exterior of a structure, we should consider knocking it down while cooling the rate of heat release from the exterior and then provide for an interior campaign. A fast, aggressive application of water will bend the odds in our favor before we go interior, reducing the risk of flashover and high-heat conditions. Also, it will probably slow the fire as well as prohibit it from extending farther to exposures within the structure. First-in companies should make this tactic a high priority when a proper size-up reveals these conditions.
Incorporated into this action is identifying the fire’s location and where it is going. Be very aware that even with this approach in sizing up a fire’s position and behavior, the fire dynamic is forever changing, especially after we leave the outside to go inside. Still, the positive aspects of this transitional approach will be well worth the effort by keeping the fire and its behavior more toward the room of origin. It will also help considerably in providing a wider window for occupant survivability and rescue.
When applying an exterior stream to reduce the fire’s energy before going inside, direct a straight or solid stream through the bottom of the window, deflect it off the ceiling, and do not rotate the nozzle. This will allow steam to vent out of the top of the window. Hitting the ceiling first is effective for fires on the first floor and even more so for fires on floors above.
This application is even more effective in reducing temperatures and limiting thermal inversions than previously thought. In the past, we believed we would be pushing fire throughout the structure and toward occupants needing rescue. The fire service should experience this tactic’s effectiveness and routinely incorporate it whenever possible because it guarantees the fastest attack possible with the quickest application of water on the fire, reducing risk to civilians and firefighters. Many times, it conserves our air supply for when we move in offensively.
Another important part of our aggressive campaign is determining structural integrity at structural fires. Although this should be part of our size-up, firefighters many times still walk into structures that looked sound and stable but that eventually collapsed. Unrecognized, unseen conditions were attacking and compromising the structure. This is especially relevant at larger structures, such as commercial or industrial buildings, because deep-seated fires many times mask compromised structural integrity. Exposure to fire and high heat for only a short time will quickly affect lightweight construction.
Although the size of a structure is usually clear from the outside, a structure’s engineered design is often hidden, elevating the risks that firefighters may encounter when deciding to aggressively go interior. It is important to note that although we must use an interior advance strategy to get to the seat of a fire at larger commercial or residential buildings, we should ensure that the fire’s extent and location are known. Always choose the shortest distance to the seat of the fire, since it can also provide a more easily accessible escape for our members if conditions should change. The fire’s size and location affect structural integrity, and we should know the structure’s ventilation profile on arrival and during the firefight. Before committing to an aggressive interior advance, we should know the relative position of fire within the structure to avoid going into areas in which the fire is above or below us. Such unrecognized fires often result in fatalities.
Understand that a transitional dynamic posture is part of offensive strategies and tactics, expediting our decision making in coordinating our fire attack and our ventilation needs and position. Aggressive fire attack and ventilation go hand in hand and are important to our survival and that of interior occupants needing rescue. Once firefighters open the front door for an interior approach, they have created a ventilation flow path that can have grave consequences, especially if combined with other preexisting or induced ventilation points. Many American fire departments continue to use PPV before and during fire attack—some positively, some with disastrous results. Sound ventilation techniques, timing, and position improve overall interior conditions, reducing risk to firefighters and civilians. Often, however, during the aggressive fire attack, only a single ventilation point (usually the front door) is created as we quickly advance onto a fire. If we are doing only this type of limited ventilation, then the fire’s ability to produce untenable conditions and prolong zero visibility takes its inevitable toll, either chasing us out of the structure or causing us severe exposure, resulting in firefighter fatalities from flashover. Along with single or multiple ventilation points that are affected by wind, this inevitably affects our ability to get to the seat of the fire and extinguish it. Wind causes fire to increase in size as well as spread rapidly throughout a structure, overtaking our ability to put the fire out as well as causing civilian and firefighter fatalities.
Cautious Aggressive Posture
On arrival at structural fires, first-in companies all too commonly quickly assess the situation and then announce that they will employ interior offensive operations. In reality, we should think cautiously as the first-arriving members are establishing an aggressive dynamic posture. Many fire service commanders and authors have used the term “marginal mode” on the fireground as if this were part of the attack strategy. Fire departments should remove this term from their operating procedures. It is an unclear communication that is open to interpretation. If chief officers and firefighters feel that something is marginal or that it could go either way, they should probably take the defensive posture first and then reassess. The cautious aggressive posture should exist throughout the entire fire attack. Fire departments and their members should concentrate on thorough size-ups and more committed actions, either defensive or offensive (photo 3).
 |
| (3) Fire companies advance into the structure offensively while maintaining caution and monitoring the free fire ventilation showing. |
Many times, we say we are committing to interior operations, but we should consider ourselves only in more of a transitional posture until we actually cross into the immediately dangerous to life or health (IDLH) plane into zero visibility. Once we move from the transitional posture to a cautious aggressive posture, we finally commit to either defensive or offensive fire attack. We must also remember that many times, our success in saving lives and property can combine the defensive and offensive postures— but only separately, not simultaneously.
Maintain the cautious aggressive posture continually on the fireground, especially during interior actions that involve extreme fire dynamics and prolonged zero visibility, which present the most danger to interior operations. When visibility is zero, especially in the interior, consider the importance of reading smoke and its characteristics such as color, velocity, and volume.
The reality is we are posturing ourselves and our actions in a fuel-filled environment. The geographical landscape of interior structural firefighting is unique to each structure. Because of this, our orientation and situational awareness are constantly threatened. The loss of sight creates the following three predominant problems that threaten our members: loss of orientation, unrecognized signs of structural collapse, and unrecognized fire growth that leads to flashover.
Often, these conditions exist before we enter a fire structure. It is when we are working for an extended time with little progress that they truly begin to reveal themselves to us, when it becomes all too late to escape.
One of the most important tools of the fire service in recent years has been the thermal imaging camera (TIC). However, our increased reliance on it on the fireground may give us a false sense of security and encourage us into more aggressive behaviors. However, with proper in-depth training, we should also realize the TIC’s limitations, which users may often overlook.
TICs can often reduce the situational awareness because what is seen is misinterpreted and temperature variances are relied on too heavily. Combined with tunnel vision, this can put members into compromised and unexpected positions, especially during an interior firefight in limited visibility. A TIC displays only surface temperatures, not below-surface temperatures, so it will show temperatures on the floor you are on but not on the floor below. Another misconception is that the TIC can see through walls and glass. These are just some of the factors that may mislead us into more aggressive actions, often with disastrous results.
Do not tolerate a marginal mode of attack on the fireground. Instead, consider a cautious posture, which can be offensively or defensively aggressive. Firefighters involved in firefights, especially in modern lightweight construction, are placing themselves in high-risk exposure, since they can become lost, trapped, or overrun by fire. Maintain a cautious mindset during aggressive actions, understand that the fire environment may present the unexpected at every fire, and realize that no two fires are ever alike. Whether the fire is in a compartmentalized or a more open structure, the interior environment provides the possibilities of smoke, rollovers, flashovers, smoke explosions, and backdrafts, which can occur at any time, in any structure, in any fire. Our offensive actions over extended periods of time during interior firefighting will have consequences that sooner or later will overtake us if we cannot produce a fast and overwhelming force with determined progress on fire extinguishment and early occupant survival and rescue. The cautious aggressive posture provides a solid format for a minimal risk management plan for every firefighter on the fireground. The time spent inside a structure and the visibility that fire conditions create drive our fire extinguishment efforts and determine true occupant survivability.
When conditions decline, the parameters tighten, and occupant survivability diminishes, we must readjust and think more about getting out. On arrival, visualize conditions and the diminished possibilities of occupant survival before going in. There are always the options for the aggressive offensive fire attack with quick applications of water on fire showing from the outside, increasing safety and survival for civilians and firefighters, and then quickly moving in for the aggressive interior attack.
Occupant survivability is compromised not only because of exposure to flame but, more importantly, exposure to the products of combustion. How long a victim can survive a fire depends more on his inhalation of fire gases and smoke. When trapped or overcome within compartmentalized or enclosed areas within a structure, occupants suffer respiratory tract burns. Other deadly gases, such as carbon monoxide and hydrogen cyanide, further reduce the victim survivability profile to a very low threshold against time. Rarely can a structure’s occupant endure these conditions for more than 10 minutes.
So the time from the fire’s incipient stage to our arrival becomes the critical factor in saving lives. Saving lives requires the offensive mode and the offensive attack posture, which always incorporates life rescue and fire extinguishment. To firefighters arriving at a well-involved fire, so much has been lost with so little to gain that the effect of aggressive offensive endeavors is questionable. The potential for early collapse because of lightweight structural components compounds the problem with even greater risks.
However, we should not give up our proud heritage of aggressive firefighting. We can still be aggressive and perform quick actions by recognizing and creating more proactive actions. We can act more aggressively if we do the following in our cautious aggressive transitional posture:
- Recognize the potential for long periods of low to near zero visibility.
- Complete a visualization that incorporates a 360° size-up.
- Create proper ventilation openings that effect proper fire flow paths.
- Hit certain fire volumes from the exterior for quick knockdowns, thus decreasing fire and heat release rates.
- Interior visibility should improve in less than 10 minutes for an aggressive interior firefight to continue.
Taking proper actions and postures at structural fires will improve firefighter and civilian survival profiles. A more accurate sense of our risk vs. reward capabilities on arrival allows us a more intelligent, quick-thinking decision making process in such a fast-paced, dangerous environment, justifying our aggressive action.
<Previous Displaying 2/3 Page 1, 2, 3 Next>
View Article as Single page
More Fire Engineering Issue Articles
Fire Engineering Archives
