Transistion is Not a Mode

Transistion is Not a Mode


A fire department responded to a reported fire in a ranch-style dwelling that had a walkout basement directly below the living area in the center of the structure. On arrival, members found heavy fire conditions in the basement and the first-floor living room. Fire had extended to the attic area and was through the roof.

The incident commander (IC) assessed the situation and announced a defensive-mode attack. Two 212-inch lines were deployed, one in front to attack the living room area and the other around the rear for penetration into the basement area through the walkout doors. Eventually, control was achieved, and the fire area was almost extinguished. Only spot fires and some small flaming along the roof`s peak remained. The center portion of the roof was gone, but the end sections were intact and stable (see Figure 1 on page 113). The living room and basement had suffered severe fire damage, and the strength of the floor was very questionable.

One 112-inch line was cautiously advanced through the front door located between the living room and bedroom areas; two firefighters were assigned to enter and extinguish the spot fires and start overhaul in the bedroom area (see Figure 2 on page 113). With the spot fires out, one firefighter moved away from the other and entered the living room area. The floor collapsed from his weight, and he partially fell through. Other firefighters helped pull him from the hole, and no injuries were incurred. Yet, the potential for an injury from falling through to the basement floor was there. Fortunately, the fire in the basement area was all but extinguished at the time. Had the firefighter remained in the area to which he had been assigned, a relative degree of safety would have been afforded and this “close call” would not have occurred.

This rather “typical” fire illustrates certain important points that apply when defensive operations are employed and a gradual movement is made closer to or into the building for final extinguishment. Repeatedly, firefighters can be observed gravitating toward the fire building when large and master streams are shut down. However, in this case, there was control–a specific assignment had been made. What happened? Is this an accident that could not have been prevented? Was there a transition from defensive to offensive modes?


The National Fire Academy defines the following three modes: (1)

Offensive. The IC chooses to make an aggressive interior attack.

Defensive. The IC determines no entry will be made.

Transitional. Forces at the scene are switching from one operational mode to the other.

Found within the core of these definitions is the idea that offensive-mode operations are conducted in the interior and defensive-mode operations are conducted outside of the collapse zone. However, this classification system does not include many fire situations in which a defensive mode is in place but firefighters are entering an adjacent area for interior exposure protection. Confusion results when the defensive-mode tactics result in a knockdown and entry into the once-defined collapse zone starts for fire extinguishment and overhaul. Currently taught definitions lead many to define modes as interior or exterior operations, making it easy for a firefighter to lose sight of the fact that interior operations can be conducted at defensive-mode fires.


Transition from offensive to defensive, or the reverse, is a process, not a mode in and of itself. Because modes inherently reference the collapse zone, this term should be included in the definitions of modes:

Offensive. Movement within the building for the purpose of bringing about rescue or control of the fire.

Defensive. An attack on the fire from a position outside of a collapse zone. The attack could be interior or exterior.

Transition process. Movement occurs from part or all of the building to outside of a designated collapse zone line (offensive to defensive), or movement occurs from outside the collapse zone to an area once considered the collapse zone but which was redesignated after careful assessment (defensive to offensive).

The critical difference is that modes should define where one should be standing and “transition” is a process, not a mode. The definitions above eliminate the interpretation that the building is automatically a collapse zone because it has a fire within it.

If the term “collapse zone” is used to identify apparatus or personnel placement at a routine fire, then it is being used in error. The correct term should be “operational zone or area.” All building fires have the potential for collapse; many, however, do not hold the possibility of collapse.


A firefighter may become confused when a collapse zone is changed even though the mode has not been changed. Looking on “transition” as a mode of operation adds to the confusion.

Transition involves a mode change, the process of change from one mode to another. Unless a mode change is clearly and effectively communicated, firefighters should assume that they will remain in the mode that had been previously announced even though the collapse zone perimeter changes. And these zone perimeter changes do occur.

At an offensive-mode fire, conditions worsen, and the IC orders evacuation of all or part of the building, establishing a collapse zone. This zone may later be expanded. Collapse zone lines change; they expand and contract as conditions change.

Not unlike a hazardous materials incident in which initial isolation and work zones are established only to change as the incident allows further assessment, a fire may start with an exterior collapse zone perimeter that is then reduced in size as careful assessment of the building is made. Interior operations can be conducted at defensive-mode fires. Fires are dynamic, and change should be expected. We are academic if we don`t realize that.

Too often, we oversimplify collapse zone perimeters with a light-switch mentality: If the collapse zone is identified as always being exterior to the building, then any inside operation must be viewed as a transition to offensive. And, it will be! Rather, we should have a dimmer-switch mentality, recognizing that the collapse zone may be adjusted–indeed, being inside of the structure–as conditions positively change and progress is made, such as what happened at the scenario presented above.

Depicted in Figure 4 on page 113 is a Detroit fire incident. On arrival, fire companies found the center portion fully involved with a partial roof collapse. Since each of the five sections was self-supporting, an aerial attack was made on the center area while 212-inch lines were stretched into the adjacent sections for interior exposure protection. The fire was in a defensive mode, yet interior operations were in place. It was clearly communicated to fire officers and firefighters that the collapse zone was the center portion of the building and that they should not advance into that area.


Not disregarding the fact that excessive destruction and water weight are a concern, many defensive-mode fires find a diminishing collapse zone line. In the case of the fire mentioned earlier, the collapse zone line diminished from an exterior position to one inside the structure–namely, an imaginary line across the living room and bedroom areas (see Figures 2 and 3 on page 113). The attack mode at this fire didn`t change; the collapse zone perimeter did.

This is typical at fires. The IC announces a defensive-mode fire and, once knockdown has occurred, firefighters are cautiously brought into adjacent areas to save what they can. If a proper assessment has been made, the firefighters are relatively safe unless they cross the line as the firefighter did in the above scenario.

Needless to say, any entry into any structure presents a collapse hazard. Sitting here typing this, I am exposed to a potential, although unlikely, collapse of this building. What we have failed to do is to adequately define what a collapse zone really is. Our definition today is based on full involvement and the obvious collapse of roof and walls. Yet, many of the fires fought are not of this nature. A simple room-and-contents fire that has not extended to structural members should not be considered a collapse zone.

A mattress fire severely weakens the bedroom floor but otherwise is contained to the room of origin. Is there a collapse zone? Certainly! But not throughout the whole structure. Operations that include checking for fire extension and salvage can be conducted safely in other areas of the building. The collapse potential is isolated to one room.

We can define the collapse zone as the area in which probable collapse can occur in part or all of a fire-weakened building. It is the “likelihood” of collapse that determines that a collapse zone be designated. Of course, this is subjective, and the definition of that area, if one is designated, rests with the experience and competence of the IC. The collapse zone has to be based on the subjective term “reasonable risk.” If we use a light-switch mentality, then entering any structure is unreasonable because they all have the potential, but not necessarily the possibility, for collapse.

We should become more cautious and professional in defining and adjusting our collapse zones. Before any adjustment is made, the building should be assessed for damage and the interior areas that provide reasonable safety as well as those that hold the possibility of collapse should be identified. Once a knockdown has occurred, what is the hurry? Why not take the time to tape an interior collapse zone area, like we tape a hazardous materials or crime scene?


At scenes that go from offensive to defensive, we make grand announcements. We blow the sirens, air horns, and anything else that makes noise. Yet, during defensive to offensive mode changes, we fail to make any announcements. The average firefighters, intent on doing their jobs, never consider that moving into the structure can be done during a defensive-mode fire. Instead, they assume that they are in transition. Eventually, they cross the line, taking an offensive action during a defensive-mode fire. There has to be greater emphasis on communicating the mode in which firefighters are operating. Until a general announcement is made at a defensive-mode fire, firefighters must recognize that the mode remains defensive and that a collapse zone exists. They must also recognize that they are not in “transition.” Transition is not a mode.

When interior exposure operations are in effect, firefighters must be given information as to where the interior collapse zone line is. Announcing “Remember, this is still a defensive-mode fire!” is insufficient information. The new line must be identified and communicated as well, especially if the firefighter(s) involved are inexperienced, display a “macho” mentality, or are prone to freelancing.

An officer should be with the interior crew at all times and be held responsible for keeping the crew together in the area that provides a relative degree of safety–the assigned area. Collapse zone line adjustments must be communicated.

Standard operating procedures should require that an announcement of a mode change from defensive to offensive be made before firefighters can “roam” into what was once the collapse zone. Until the announcement is made, overhaul and final extinguishment operations can be conducted only outside of the collapse zone.

SOP training should stipulate that a collapse zone is not just a line drawn around a building but, in many cases, looks more like a cross, allowing corner access for exposure line deployment. And firefighters must have the discipline to remain in that relatively safe location and not move forward and in between the structures. In 1992, three firefighters died in two separate incidents when they advanced exposure protection lines from a safe corner position into the collapse zone between the buildings.2

In training programs, I show students a slide of aerial towers in operation and ask them to identify the fire mode. The response is always “defensive.” I show another slide of the same fire with one of the aerial platforms shut down and ask the same question. The response is “offensive.” We have trained our firefighters to recognize a defensive-mode fire as one in which master streams are used and an offensive-mode fire as one in which they are not. This visual message is inadequate for maintaining fireground control in that the message is interpreted to mean it is time to approach or even enter the building. Firefighters are affected by that “gravitational pull” of the fire.

Most firefighters strive to do a good job but, captured by the excitement of the incident, they too easily develop a narrowed focus of the job in front of them. To many, moving hoselines inside means they are in a transitional mode because incident commanders, departmental regulations, and SOPs fail to address that a collapse zone can exist while interior operations are being conducted.

Training all personnel in collapse zone definitions should include placement of interior and exterior exposure protection streams and how to safely access an exterior corner position: that as the fire is controlled, collapse zones may be adjusted; that interior collapse zone lines can exist, as do exterior collapse zone lines; and that until an announcement or broadcast is made, the fire will remain in the mode designated by the IC, even if a closer (possibly interior) approach is being allowed.

Since 1987, at least 19 firefighters have died at defensive-mode fires.3 Most of them were in exterior positions but inside the collapse zone. Most of them were involved in exposure-protection operations. Defining the operational mode by the location in which the activity is being conducted causes confusion and loss of fireground discipline. Understanding that “transition” is not a mode but the process of switching from one mode is another key to understanding that operations must remain within only one of two operational modes. Unless the IC announces the mode change, no change in mode has occurred, even if exterior operations are now moving interior. If no mode change has occurred, firefighters should be asking what the new collapse zone lines are.

Operational modes rely heavily on defining the collapse zone. Yet, we have not taken the time to recognize that collapse zones may be interior as well as exterior. Nor have we recognized that interior operations can be conducted at defensive-mode fires. We add to a firefighter`s confusion by defining transition as a mode rather than as the process of changing from one mode to another. It is very probable that the firefighter who fell through the weakened floor in the scenario above would have identified the mode as transition or offensive when in fact the IC would have viewed it as defensive but with an adjusted collapse zone.


When we announce the mode of operations at a fire, we expect certain behaviors from the firefighters. At offensive-mode fires, we expect aggressive interior attack. At defensive-mode fires, we expect firefighters to remain outside of the collapse zone and surround and drown the fire building. When we transition from offensive interior attack to exterior defensive operations, the expectations are clear. RUN!

Our major problem is a defensive-mode fire that moves toward a closer, possibly interior approach once the fire has been knocked down. What behavior do we expect from a firefighter? If I ask you what behavior is expected of you while we “transition” from defensive to offensive operations, what would your answer be? Viewing transition as a mode makes unclear the type of behavior expected and is useless as a communication tool.

Clear communications that identify modes and collapse zones are needed. In addition, SOPs should define what defensive and offensive modes are in clear language and based on everyday fire operations. Defining “transition” as a process instead of as a mode would allow firefighters to clearly see the distinction between defensive and offensive modes, whether interior or exterior to the building, because they would see that transition is not a mode. n


1. “Managing Company Tactical Operations–Preparation” Instructor Guides, National Fire Academy.

2. “Fire Fighter Fatality Report,” NFPA Fire Journal, July/Aug. 1993.

3. My preliminary research on firefighter fatalities from 1987 to 1996, based on National Fire Protection Association case studies in the NFPA Fire Journal and other news sources.

Click here to enlarge image

Click here to enlarge image

n JOHN A. REARDON is a retired lieutenant from the Detroit (MI) Fire Department. He currently owns and operates John A. Reardon & Associates, Inc., a safety training firm in Commerce Township, Michigan.

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