Posts Tagged ‘near miss’

My last post, Hazards Above, provided a brief overview of three incidents involving extreme fire behavior in the attic or truss loft void spaces of wood frame dwellings. This post will examine the similarities and differences between these lessons and identify several important considerations when dealing with fires occurring in or extending to void spaces. At the conclusion of Hazards Above, I posed five questions:

1. What is similar about these incidents and what is different?
2. Based on the limited information currently available, what phenomena do you think occurred in each of the cases? What leads you to this conclusion?
3. What indicators might have pointed to the potential for extreme fire behavior in each of these incidents?
4. How might building construction have influenced fire dynamics and potential for extreme fire behavior in these incidents?
5. What hazards are presented by fires in attics/truss lofts and what tactics may be safe and effective to mitigate those hazards?

Similarities and Differences

The most obvious similarities between these incidents was that the buildings were of wood frame construction, the fire involved or extended to an attic or truss loft void space, and that some type of extreme fire behavior occurred. In two of the incidents firefighters were seriously injured, while in the other firefighters escaped unharmed.

Given the limited information available from news reports and photos taken after the occurrence of the extreme fire behavior events, it is not possible to definitively identify what types of phenomena were involved in these three incidents. However, it is interesting to speculate and consider what conditions and phenomena could have been involved. It might be useful to examine each of these incidents individually and then to return to examine fire behavior indicators, construction, and hazards presented by these types of incidents.

Minneapolis, MN

In the Minneapolis incident the fire occurred in an older home with legacy construction and relatively small void spaces behind the knee walls and above the ceiling on Floor 3. The triggering event for the occurrence of extreme fire behavior is reported to be opening one of the knee walls on Floor 3. As illustrated in Figure 1, the fire appeared to transition quickly to a growth stage fire (evidenced by the dark smoke and bi-directional air track from the windows on Floor 3 Side A. However blast effects on the structure are not visible in the photo and were not reported.

Figure 1. Minneapolis MN Incident: Conditions on Side A

Note: Photo by Steve Skar

Potential Influencing Factors: While detail on this specific incident is limited, it is likely that the fire burning behind the knee wall was ventilation controlled and increased ventilation resulting from opening the void space resulted in an increase in heat release rate (HRR). Potential exists for any compartment fire that progresses beyond the incipient stage to become ventilation controlled. This is particularly true when the fire is burning in a void space.

Extreme Fire Behavior: While statements by the fire department indicate that opening the knee wall resulted in occurrence of flashover, this is only one possibility. As discussed in The Hazard of Ventilation Controlled Fires and Fuel and Ventilation, increasing ventilation to a ventilation controlled fire will result in increased HRR. Increased HRR can result in a backdraft (if sufficient concentration of gas phase fuel is present), a vent induced flashover, or simply fire gas ignition (such as rollover or a flash fire) without transition to a fully developed fire.

Harrisonburg, VA

The Harrisonburg incident involved extreme fire behavior in Exposure D (not the original fire unit). The extreme fire behavior occurred after members had opened the ceiling to check for extension. However, this may or may not have been the precipitating event. As illustrated in Figure 2, as members prepare to exit from the windows on Floor 3 , Side C, flames are visible on the exterior at the gable, but it appears that combustion is limited to the vinyl siding and soffit covering. There are no indicators of a significant fire in Exposure D at the time that the photo was taken. However, it is important to remember that this is a snapshot of conditions at one point in time from a single perspective.

Figure 2. Harrisonburg, VA Incident: Conditions on Side C

Note: Photo by Allen Litten

Potential Influencing Factors: The truss loft was likely divided between units by a 1 hour fire separation (generally constructed of gypsum board over the wood trusses). While providing a limited barrier to fire and smoke spread, it does not generally provide a complete barrier and smoke infiltration is likely. Sufficient smoke accumulation remote from the original fire location can present risk of a smoke explosion (see NIOSH Report 98-03 regarding a smoke explosion in Durango, Colorado restaurant). Alternately, fire extension into the truss loft above an exposure unit can result in ventilation controlled fire conditions, resulting in increased HRR if the void is opened (from above or below).

Extreme Fire Behavior: Smoke, air track, and flame indicators on Side C indicate that the fire in the truss loft may not have continued to develop past the initial ignition of accumulated smoke (fuel). It is possible that smoke accumulated in the truss loft above Exposure B and was ignited by subsequent extension from the fire unit. Depending on the fuel (smoke)/air mixture when flames extended into the space above Exposure B ignition could have resulted in a smoke explosion or a less violent fire gas ignition such as a flash fire.

Sandwich, MA

In the Sandwich incident, the extreme fire behavior occurred shortly after the hose team applied water to the soffit. However, this may or may not have been the precipitating event. As illustrated in Figure 3, the fire transitioned to a fully developed fire (likely due to the delay in suppression as the injured members were cared for). Blast effects on the structure are obvious.

Figure 3: Sandwich, MA: Conditions on Sides C and D

Note: Photos by Britt Crosby (http://www.capecodfd.com)

Potential Influencing Factors: The roof support system in this home appears to have been constructed of larger dimensional lumber (rather than lightweight truss construction). In addition, it is likely that the attic void spaces involved in this incident were large and complex (given the size of the dwelling and complex roof line). It appears that at least part of the home had a cathedral ceiling. Fire burning in the wood framing around the metal chimney would have allowed smoke (fuel) and hot gases to collect in the attic void in advance of fire extension.

Extreme Fire Behavior: The violence of the explosion (see blast damage to the roof on Side D in Figure 3) points to the potential for ignition of pre-mixed fuel (smoke) and air, resulting in a smoke explosion. However, it is also possible that failure of an interior ceiling (due to water or steam production from water applied through the soffit) could have increased ventilation to a ventilation controlled fire burning in the attic, resulting in a backdraft).

Fire Behavior Indicators

The information provided in news reports points to limited indication of potential for extreme fire behavior. One important question for each of us is how we can recognize this potential, even when indicators are subtle or even absent.

Important! A growth stage fire can present significant smoke and air track indicators, with increasing thickness (optical density), darkening color, and increasing velocity of smoke discharge. However, as discussed in The Hazard of Ventilation Controlled Fires, when the fire becomes ventilation controlled, indicators can diminish to the point where the fire appears to be in the incipient stage. This change in smoke and air track indicators was consistently observed during the full-scale fire tests of the influence of ventilation on fires in single-family homes conducted by UL earlier this year.

Even with an opening into another compartment or to the exterior of the building, a compartment fire can become ventilation controlled. Consider building factors including potential for fire and smoke extension into void spaces in assessing fire conditions and potential for extreme fire behavior. A ventilation controlled fire or flammable mixture of smoke and air may be present in a void space with limited indication from the exterior or even when working inside the structure.

Building Construction

Each of these incidents occurred in a wood frame structure. However, the construction in each case was somewhat different.

In Minneapolis, the house was likely balloon frame construction with full dimension lumber. As with many other structures with a “half-story”, the space under the pitched roof is framed out with knee walls to provide finished space. This design is not unique to legacy construction and may also be found with room-in-attic trusses. The void space behind the knee wall provides a significant avenue for fire spread. When involved in fire, opening this void space can quickly change fire conditions on the top floor as air reaches the (likely ventilation controlled) fire.

The incident in Harrisonburg involved a fire in a townhouse with the extreme fire behavior phenomena occurring in an exposure. While not reported, it is extremely likely that the roof support system was comprised of lightweight wood trusses. In addition, there was a reverse gable (possibly on Sides A and C) that provided an additional void. As previously indicated, the truss loft between dwelling units is typically separated by a one-hour rated draft stop. Unlike a fire wall, draft stops do not penetrate the roof and may be compromised by penetrations (after final, pre-occupancy inspection). Installed to code, draft stops slow fire spread, but may not fully stop the spread of smoke (fuel) into the truss lofts above exposures.

Firefighters in Sandwich were faced with a fire in an extremely large, wood frame dwelling. While the roof appeared to be supported by large dimensional lumber, it is likely that there were large void spaces as a result of the complex roofline. In addition, the framed out space around the metal chimney provided an avenue for fire and smoke spread from the lower level of the home to the attic void space.

Hazards and Tactics

Forewarned is forearmed! Awareness of the potential for rapid fire development when opening void spaces is critical. Given this threat, do not open the void unless you have a hoseline in hand (not just nearby).

Indirect attack can be an effective tactic for fires in void spaces. This can be accomplished by making a limited opening and applying water from a combination nozzle or using a piercing nozzle (which further limits introduction of air into the void).

If there are hot gases overhead, cool them before pulling the ceiling or opening walls when fire may be in void spaces. Pulses of water fog not only cool the hot gases, but also act as thermal ballast; reducing the potential for ignition should flames extend from the void when it is opened.

Lastly, react immediately and appropriately when faced with worsening fire conditions. Review my previous posts on Battle Drill (Part 1, Part 2, and Part 3). An immediate tactical withdrawal under the protection of a hoseline is generally safer than emergency window egress (particularly when ladders have not yet been placed to the window).

Ed Hartin, MS, EFO, MIFireE, CFO

It has been a number of months since the last Reading the Fire post. It is essential to continue the process of deliberate practice in order to continue to improve and refine skill in Reading the Fire.

As we start the New Year it is a good time to reaffirm our commitment to mastering our craft. Developing and maintaining proficiency in reading the Fire using the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) organizing scheme for fire behavior indicators, requires practice. This post provides an opportunity to exercise your skills using a video segment shot during a residential fire.

Residential Fire

In mid-January 2010, the Gary, Indiana Fire Department was dispatched to a residential fire on Massachusetts Street at East 24^th Avenue, on arrival Battalion 4 advised of a working fire in a 2 story dwelling. While the first arriving engine was laying a supply line from a nearby hydrant, the first in truck forced entry.

Download and the B-SAHF Worksheet.

Watch the first 35 seconds (0:35) of the video. This segment was shot from Side A. �First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators; then answer the following five standard questions?

1. What additional information would you like to have? How could you obtain it?
2. What stage(s) of development is the fire likely to be in (incipient, growth, fully developed, or decay)?
3. What burning regime is the fire in (fuel controlled or ventilation controlled)?
4. What conditions would you expect to find inside this building? If presented with persons reported (as the first arriving companies were) how would you assess potential for victim survival?
5. How would you expect the fire to develop over the next two to three minutes

Now watch the remainder of the video clip and answer the following questions:

1. Did fire conditions progress as you anticipated?
2. A voice heard in the video states that this was a backdraft. Do you agree? Why or why not?

It is likely that the first in truck company in this incident made entry to search for occupants and to locate the fire. Regardless of your perspective on search with or without a hoseline, this video clip provides lessons.

• It is essential to read the fire, recognize the stage(s) of fire development and burning regime(s) in the involved compartments.
• In addition to reading current conditions, anticipate likely fire development and potential for extreme fire behavior.
• Making entry (and leaving the door fully open) creates a ventilation opening (inlet, exhaust, or both). Recognize the potential influence of changes to the ventilation profile on fire behavior.
• To borrow a phrase from a number of National Institute for Occupational Safety and Health Death in the Line of Duty reports; �Ventilation and fire attack must be closely coordinated�. One key element in this coordination is that charged lines must be in place before completion of ventilation openings. This is critical when dealing with a ventilation controlled fire.

Ed Hartin, MS, EFO, MIFIreE, CFO

Quick Review

The previous post in this series presented a video clip of an incident on the afternoon of February 18, 2010 that injured four Chicago firefighters during operations at a residential fire at 4855 S. Paulina Street.

First arriving companies discovered a fire in the basement of a 1-1/2 story, wood frame, single family dwelling and initiated fire attack and horizontal ventilation of the floors above the fire. Based on news accounts, the company assigned to fire attack was in the stairwell and another firefighter was performing horizontal ventilation of the floors above the fire on Side C when a backdraft or smoke explosion occurred. Two firefighters on the interior, on at the doorway and the firefighter on the ladder on Side C were injured and were transported to local hospitals for burns and possible airway injuries.

In analyzing the video clip shot from inside a nearby building, we have several advantages over the firefighters involved in this incident.

Time: We are not under pressure to make a decision or take action.

Reduced Cognitive Workload: Unlike the firefighters who needed to not only read the fire, but also to attend to their assigned tactics and tasks, our only focus is analysis of the fire behavior indicators to determine what (if any) clues to the potential for extreme fire behavior may have been present.

Repetition: Real life does not have time outs or instant replay. However, our analysis of the video can take advantage of our ability to pause, and replay key segments, or the entire clip as necessary.

Perspective: Since the field of view in the video clip is limited by the window and the fidelity of the recording is less than that seen in real life, it presents a considerably different field of view than that of the firefighters observed in operation and does not allow observation of fire behavior indicators and tactical operations on Sides A, B, and D.

Initial Size-Up

What B-SAHF indicators could be observed on Side C up to the point where firefighters began to force entry and ventilate the basement (approximately 02:05)?

Figure 1. Conditions at 01:57 Minutes Elapsed Time in the Video Clip

Building: The structure is a 1-1/2 story, wood frame, dwelling with a daylight basement. The apparent age of the structure makes balloon frame construction likely, and the half story on the second floor is likely to have knee walls, resulting in significant void spaces on either side and a smaller void space above the ceiling on Floor 2. One window to the left of the door on Side C appears to be covered with plywood (or similar material). Given the location of the door (and door on Side A illustrated in the previous post in this series), it is likely that the stairway to the basement is just inside the door in Side C and a stairway to Floor 2 is just inside the door on Side A.

Smoke: A moderate volume of dark gray smoke is visible from the Basement windows and windows and door on Floor 1 as well as a larger volume from above the roofline on Side B. While dark, smoke on Side C does not appear to be thick (optically dense), possibly due to limited volume and concentration while smoke above the roofline on Side B appears to be thicker. However smoke on Side C thickens as time progresses, particularly in the area of the door on Floor 1. The buoyancy of smoke is somewhat variable with low buoyancy on Side C and greater buoyancy on Side B. However, smoke from the area of the door on Floor 1 Side C intermittently has increased buoyancy.

Air Track: Smoke on Side C appears to have a faintly pulsing air track with low velocity which is masked to some extent by the effects of the wind (swirling smoke due to changes in low level wind conditions). Smoke rising above the roofline on Side B appears to be moving with slightly greater velocity (likely due to buoyancy).

Heat: The only significant heat indicators are limited velocity of smoke discharge and variations in buoyancy of smoke visible from Sides B and C. Low velocity smoke discharge and low buoyancy of the smoke on Side C points to relatively low temperatures inside the building. The greater buoyancy and velocity of smoke observed above the roofline on Side B indicates a higher temperature in the area from where this smoke is discharging (likely a basement window on Side B).

Flame: No flames are visible.

Initial Fire Behavior Prediction

Based on assessment of conditions to this point, what stage(s) of development and burning regime(s) is the fire likely to be in?

Dark smoke with a pulsing air track points to a ventilation controlled, decay stage fire.

What conditions would you expect to find inside the building?

Floors 1 and 2 are likely to be fully smoke logged (ceiling to floor) with fairly low temperature. The basement is likely to have a higher temperature, but is also likely to be fully smoke logged with limited flaming combustion.

How would you expect the fire to develop over the next few minutes?

As ventilation is increased (tactical ventilation and entry for fire control), the fire in the basement will likely remain ventilation controlled, but will return to the growth stage as the heat release rate increases. Smoke thickness and level (to floor level) along with a pulsing air track points to potential for some type of ventilation induced extreme fire behavior such as ventilation induced flashover (most likely) or backdraft (less likely). Another possibility, would be a smoke explosion; ignition of premixed gas phase fuel (smoke) and air that is within its flammable range (less likely than some type of ventilation induced extreme fire behavior)

Ongoing Assessment

What indicators could be observed while the firefighter was forcing entry and ventilating the daylight basement on Side C (02:05-02:49)?

There are few changes to the fire behavior indicators during this segment of the video. Building, Heat, and Flame indicators are essentially unchanged. Smoke above the roofline appears to lighten (at least briefly) and smoke on Side C continues to show limited buoyancy with a slightly pulsing air track at the first floor doorway.

What B-SAHF indicators can be observed at the door on Side C prior to forced entry (02:49-03:13)?

Figure 2. Conditions at 03:06 Minutes Elapsed Time in the Video Clip

Figure 3. Conditions at 03:08 Minutes Elapsed Time in the Video Clip

Building, Smoke, Heat and Flame indicators remain the same, but several more pulsations (03:05-03:13) providing a continuing, and more significant indication of ventilation controlled, decay stage fire conditions.

What indicators can be observed at the door while the firefighter attempts to remove the covering over the window adjacent to the door on Floor 1 (03:13-13:44)?

No significant change in Building, Heat, or Flame Indicators. However, smoke from the doorway has darkened considerably and there is a pronounced pulsation as the firefighter on the ladder climbs to Floor 2 (03:26). It is important to note that some of the smoke movement observed in the video clip is fire induced, but that exterior movement is also significantly influenced by wind.

What B-SHAF indicators do you observe at the window on Floor 2 prior to breaking the glass (03:44)?

Figure 4. Conditions at 03:43 Minutes Elapsed Time in the Video Clip

The window on Floor 2 is intact and appears to be tight as there is no smoke visible on the exterior. It is difficult to tell due to the angle from which the video was shot (and reflection from daylight), but it would be likely that the firefighter on the ladder could observe condensed pyrolizate on the window and smoke logging on Floor 2. It is interesting to note limited smoke discharge from the top of the door and window on Floor 1 in the brief period immediately prior to breaking the window on Floor 2.

What indicators are observed at the window on Floor 2 immediately after breaking the glass (03:44-03:55)?

Figure 5. Conditions at 03:52 Minutes Elapsed Time in the Video Clip

No significant changes in Building, Heat, or Flame indicators. Dark gray smoke with no buoyancy issues from the window on Floor 2 with low to moderate velocity immediately after the window is broken.

What B-SAHF indicators were present after the ventilation of the window on Floor 2 Side C was completed and 04:08 in the video clip (03:44-04:08)?

Buoyancy and velocity both increase and a slight pulsing air track develops within approximately 10 seconds. In addition, the air track at the door on Floor 1 shifts from predominantly outward with slight pulsations to predominantly inward, but with continued pulsation (possibly due to the limited size of the window opening on Floor 2, Side C.

Anticipating Potential Fire Behavior

Unlike the firefighters in Chicago who were operating at this incident, we can hit the pause button and consider the indicators observed to this point. Think about what fire behavior indicators are present (and also consider those that are not!).

Initial observations indicated a ventilation controlled decay stage fire and predicted fire behavior is an increase in heat release rate with potential for some type of extreme fire behavior. Possibilities include ventilation induced flashover (most likely) or backdraft (less likely), or smoke explosion (less likely than some type of ventilation induced extreme fire behavior).

Take a minute to review the indicators of ventilation controlled, decay stage fires as illustrated in Table 1.

Table 1. Key Fire Behavior Indicators-Ventilation Controlled, Decay Stage Fires

Which of these indicators were present on Side C of 4855 S. Paulina Street?

Building: The building appeared to be unremarkable, a typical single family dwelling. However, most residential structures have more than enough of a fuel load to develop the conditions necessary for a variety of extreme fire behavior phenomena.

Smoke: The dark smoke with increasing thickness (optical density) is a reasonably good indicator of ventilation controlled conditions (particularly when combined with air track indicators). Lack of buoyancy indicated fairly low temperature smoke, which could be an indicator of incipient or decay stage conditions or simply distance from the origin of the fire. However, combined with smoke color, thickness, and air track indicators, this lack of buoyancy at all levels on Side C is likely an indicator of dropping temperature under decay stage conditions. This conclusion is reinforced by the increase in buoyancy after ventilation of the window on Floor 2 (increased ventilation precipitated increased heat release rate and increasing temperature).

Air Track: Pulsing air track, while at times quite subtle and masked by swirling smoke as a result of wind, is one of the strongest indications of ventilation controlled decay stage conditions. While often associated with backdraft, this indicator may also be present prior to development of a sufficient concentration of gas phase fuel (smoke) to result in a backdraft.

Heat: Velocity of smoke discharge (air track) and buoyancy (smoke) are the only two heat indicators visible in this video clip. As discussed in conjunction with smoke indicators, low velocity and initial lack of buoyancy which increases after ventilation is indicative of ventilation controlled, decay stage conditions.

Flame: Lack of visible flame is often associated with ventilation controlled decay and backdraft conditions. However, there are a number of incidents in which flames were visible prior to occurrence of a backdraft (in another compartment within the structure). Lack of flames must be considered in conjunction with the rest of the fire behavior indicators. In this incident, lack of visible flames may be related to the stage of fire development, but more likely is a result of the location of the fire, as there is no indication that flames were present on Side C prior to the start of the video clip.

What Happened?

Firefighters had entered the building for fire attack while as illustrated in the video clip, others were ventilating windows on Side C. It is difficult to determine from the video if a window or door at the basement level on Side C was opened, but efforts were made to do so. A window on Floor 2 had been opened and firefighters were in the process of removing the covering (plywood) from a window immediately adjacent to the door on Floor 1. At 04:12, an explosion occurred, injuring two firefighters on the interior as well as the two firefighters engaged in ventilation operations on Side C.

Starting at approximately 03:59, velocity of smoke discharge from the window on Floor 2 Side C increases dramatically. At 04:08 discharge of smoke begins to form a spherical pattern as discharged from the window. This pattern becomes more pronounced as the sphere of smoke is pushed away from the window by increasing velocity of smoke discharge at 04:12, immediately prior to the explosion. Velocity of smoke discharge at the door increases between 03:59 and -4:12 as well, but as the opening is larger, this change is less noticeable. As pressure increases rapidly during the explosion a whooshing sound can be heard. After the explosion, there was no noticeable increase in fire growth.

Figure 6. Conditions at 04:08 Minutes Elapsed Time in the Video Clip

Figure 7. Conditions at 04:09 Minutes Elapsed Time in the Video Clip

Figure 8. Conditions at 04:10 Minutes Elapsed Time in the Video Clip

Figure 9. Conditions at 04:11 Minutes Elapsed Time in the Video Clip

Figure 10. Conditions at 04:12 Minutes Elapsed Time in the Video Clip

Figure 11. Conditions at 04:13 Minutes Elapsed Time in the Video Clip

Based on observation of fire behavior indicators visible in the video clip, we know that a transient extreme fire behavior event occurred while a crew was advancing a hoseline on the interior and ventilation operations were being conducted on Side C. What we don�t know is what firefighting operations were occurring on the other sides of the building or in the interior. In addition, we do not have substantive information from the fire investigation that occurred after the fire was extinguished.

The Ontology of Extreme Fire Behavior presented in an earlier post classifies these types of phenomena on the basis of outcome and conditions. As a transient and explosive event, this was likely a backdraft or smoke explosion. In that this occurred following entry and during ongoing ventilation operations, I am inclined to suspect that it was a backdraft.

Indicators visible on Side C provided a subtle warning of potential for some type of ventilation induced extreme fire behavior, but were likely not substantially different from conditions observed at many fires where extreme fire behavior did not occur.

As the title of the wildland firefighting course S133 states; Look Up, Look Down, Look Around! Anticipation of fire development and extreme fire behavior requires not only recognition of key indicators, but that these indicators be viewed from a holistic perspective. Firefighters and/or officers performing a single task or tactical assignment may only see part of the picture. It is essential that key indicators be communicated to allow a more complete picture of what is occurring and what may occur as incident operations progress.

Ed Hartin, MS, EFO, MIFireE, CFO

Two recent events in Baltimore, Maryland and Gary, Indiana point to the criticality of recognizing key fire behavior indicators and understanding practical fire dynamics.

Five Firefighters Injured in Baltimore

Early on the morning of Friday, January 15, 2010, the Baltimore City Fire Department was dispatched to a residential fire Southeast Baltimore. First arriving companies observed a row house of ordinary construction with a large volume of smoke and flames issuing from the basement and extending to the first floor.

According to a department spokesperson, the first engine took a line through the front door to the rear kitchen area where crew had some trouble finding the basement stairs. Another engine company went to the rear with a line to the outside stairwell leading to the basement and was just starting down the stairs. The first truck vented some skylights on the roof as well as the front basement windows. As crews were attempting to access the fire, some type of transient extreme fire behavior resulted in flames blowing through the unit and out the front door, rear stairwell, second floor windows, and skylights. The firefighter from the first arriving truck assigned to the roof described the sound of a freight train coming through.

Five firefighters injured as a result of this explosive fire behavior phenomenon were transported to area hospitals. The officer of the first in engine company was admitted to the Bayview Burn Center, where he is listed in stable condition

Find more videos like this on firevideo.net

What Happened?

As always when a video of an incident involving extreme fire behavior is posted to the web, there is ongoing debate about what happened. Was it a backdraft? Was it a flashover? An interesting debate, but the value is not so much in being �right�, but in understanding how these phenomena occur, what might have happened in this incident, key indicators that may (or may not) be visible in the video, and most importantly how to prevent this from happening to us and the firefighters that we work with!

Flashover: sudden transition to fully developed fire. This phenomenon involves a rapid transition to a state of total surface involvement of all combustible material within the compartment.

Given adequate fuel and ventilation, a compartment fire may reach flashover as it develops from the growth to fully developed stage. However, when fire development is limited by the ventilation profile of the compartment, changes in ventilation will directly influence fire behavior.

For many years firefighters have been taught that ventilation reduces the potential for flashover. However, when a fire is ventilation controlled, heat release rate is limited by the available oxygen. Under these conditions; increasing air supply by creating opening results in increased heat release rate. This increased heat release rate may result in flashover.

If a fire is sufficiently ventilation controlled and a high concentration of excess pyrolizate and unburned flammable products of combustion accumulate in a compartment, the outcome of increased ventilation may be different.

Backdraft: Deflagration of unburned pyrolyzate and combustion products following introduction of air to a ventilation controlled compartment fire and ignition of the fuel/air mixture. This deflagration results in a rapid increase in pressure within the compartment and extension of flaming combustion through compartment openings. Occurrence of this phenomenon requires an atmosphere in which the fuel concentration is too high to deflagrate without introduction of additional oxygen.

As introduced in Extreme Fire Behavior: An Organizational Scheme, extreme fire behavior phenomena can be classified on the basis of outcome and conditions (see Figure 1)

Figure 1. Extreme Fire Behavior Classification.

Use of this approach may aid in making sense of what may have occurred in the Baltimore incident. But, it is often difficult to classify extreme fire behavior phenomena into discrete, black and white categories. What is the dividing line between a ventilation induced flashover and a backdraft. One key difference may be the speed with which heat release rate increases, but where is the dividing line (see Figure 2)?

Figure 2. The Gray Area.

Keep in mind that while being right is great, it is more important to work through the process of figuring things out to improve your understanding.

Near Miss in Gary

Monday morning January 18, 2010 firefighters in Gary, Indiana were operating at a residential fire at 24^th and Massachusetts when they experienced a near miss involving rapid fire progression. Have a look at video of this incident and give some thought to what influenced fire behavior. Also look at the similarities and differences between the extreme fire behavior that occurred in the Baltimore and Gary incidents.

Back on Task!

I have been extremely busy working on a project for the National Institute for Occupational Safety and Health and preparing for the International Fire & Rescue Congress in Valdivia, Chile. Next week�s post will provide a quick update on training conducted at the Congress.

After returning from Chile, I will be back on task with examination of the concept of battle drills to develop effective reaction to worsening fire conditions while operating in an offensive mode.

Ed Hartin, MS, EFO, MIFireE, CFO

Quantitative Analysis

Quantitative analysis of firefighter injuries and fatalities uses statistics to describe what has occurred and identify patterns and trends. Annual reports and longitudinal (multi-year) quantitative studies provide one way to examine firefighter safety performance.

• Firefighter Fatalities in the United States 2007, National Fire Protection Association (NFPA)
• U.S. Fire Service Fatalities in Structure Fires, 1977-2000, NFPA
• Firefighter Fatalities in the US in 2007, United States Fire Administration (USFA)
• Firefighter Fatality Retrospective Study, USFA

Examination of firefighter fatalities and injuries over time requires consistency of method when comparing data from year to year. However, dividing fatalities and injuries into a small number of causes or injury or death provides a coarse grained picture of the problem. This is useful, but not sufficient.

Reporting system limitations in dealing with multiple causal and contributing factors also limits firefighter injury and fatality statistical analysis and reporting. Quantitative analysis is extremely useful in identifying trends and pointing to issues needing further examination. Identification of the increasing rate of firefighter fatalities inside buildings during structural firefighting is one example. However data and system limitations may preclude a fine grained quantitative analysis of this issue.

Qualitative Analysis

Qualitative analysis of firefighter injuries and fatalities often involves examination of individual incidents, describing in detail what happened in that specific case and identifying causal and contributing factors. The limited information provided by annual reports and longitudinal analysis of firefighter injuries and fatalities can be enhanced by examining individual cases.

The NIOSH Firefighter Fatality Investigation and Prevention Program investigates many firefighter fatalities as a result of trauma (see the NIOSH Decision Matrix). However, they do not generally investigate non-fatal incidents and do not investigate near miss events. In addition to not examining all traumatic fatalities there is often a considerable delay in beginning the investigative process. This delay may result in the building involved being demolished and loss of important detail in witness interviews.

My last two posts looked at the US Forest Service approach to Investigating Wildland Fire Entrapments and Peer Review Process to identify lessons learned. Application of these methods in structural firefighting would provide an excellent method for improving our understanding of applied fire dynamics, tactical operations, and decision-making as well as other hazards such as structural collapse, and firefighter disorientation.

The Way Forward

Fire service organizations should examine all events that involve structural fire entrapment, collapse entrapment, and disorientation. There are no commonly accepted definitions for these types of events. However, the US Forest Service definition for wildland fire entrapment could serve as a starting point for defining entrapment and disorientation in the structural environment.

• Structural Fire Entrapment: a fire behavior related event involving compromise of normal (planned) means of egress; or thermal exposure resulted in, or had significant potential for death, injury, or damage to personal protective equipment.
• Collapse Entrapment: A structural failure related event involving compromise of normal (planned) means of egress, or impact resulting from structural failure (load bearing or non-load bearing) that resulted in, or had significant potential for death, injury, or damage to personal protective equipment.
• Disorientation Entrapment: Loss of spatial orientation while operating in a hazardous atmosphere that resulted in, or had significant potential for death or injury.

Note that like the US Forest Service definition of wildland fire entrapment; these events are inclusive of fatalities, injuries, and near miss events.

Investigating a near miss or accident involving a serious injury or fatality may present significant challenges to an individual agency in terms of resources and expertise. Individuals and organizations also filter information through cultural norms which define “the way we do things”. Use of a multi-agency team reduces these potential challenges. However, as in emergency response, it is important to define the process and develop effective working relationships prior to facing a serious injury or fatality investigation.

Who should be involved? Adapting from the US Forest Service Investigating Wildland Fire Entrapments individuals with the following skill sets should be involved in structural fire, collapse, or disorientation entrapment events.

• Command Officer
• Safety Officer
• Fire Behavior Specialist
• Structural Specialist (collapse entrapment)
• Fire Investigator
• Personal Protective Equipment Specialist (may be an external resource)
• Photographer/Videographer

There are a number of considerations in determining the makeup of the investigative team. Depending on the nature of the investigation, some of these skill sets may not be as critical or a single individual may fill more than one role (e.g., fire investigator and photographer). Unlike the wildland community, there is considerably less clarity to specialization in structural fire behavior. In some cases this may be a fire investigator with specific training in fire dynamics and fire modeling, in others it may be a compartment fire behavior instructor. This will depend on the nature of the incident and available resources. In addition, the technical complexity of assessing personal protective equipment performance (particularly self-contained breathing apparatus) may require specialized external expertise.

As in wildland incidents, there is also great value in peer review of structural incidents. Like the more formal investigation, peer review is a team based process, but the team is comprised of a small group of experienced firefighters and fire officers who are known to be insightful, fair, just, and honest.

A Call to Action

There is not a simple cookbook approach to developing processes for entrapment investigation and peer review. The first step is to identify how your organization can effectively identify and communicate lessons learned. While serious accidents and injuries present a significant challenge, near miss events occur much more frequently and provide an opportunity for individual and organizational learning as well as an opportunity to develop the entrapment investigation and peer review processes. The following two actions provide the opportunity to improve firefighter safety while operating offensively at structure fires:

• Members submit near miss reports to the National Firefighter Near Miss Program
• Agencies use a team based, multi-agency approach to investigate structure fire, collapse, and disorientation entrapments (inclusive of near miss events).
• Agencies widely share their lessons learned with other fire service agencies and organizations

Please post your thoughts on this process and how we can best develop and communicate lessons learned from entrapment events occurring during structure fires.

Ed Hartin, MS, EFO, MIFireE, CFO

Structural firefighting agencies can draw some valuable lessons from the wildland firefighting community. Fire behavior training in many structural agencies often begins and ends in recruit academy. For wildland firefighters, fire behavior training involves an extensive, multi-level curriculum (S-190, S290, S-390, S-490 and so on). The wildland community is also more substantively engaged in analysis of fatalities, accidents, and near miss events with the intention of impacting policy, procedure, and performance. This is not to say that they have a perfect safety record, far from it. However, this ongoing effort to identify and implement best practice based on lessons learned is worthy of emulation.

The US Forest Service Technology & Development Program produced a document titled Investigating Wildland Fire Entrapments which outlines the process that should be used and documentation required for entrapment related incidents. Entrapments are:

A situation where personnel are unexpectedly caught in a fire behavior related, life-threatening position where planned escape routes and safety zones are absent, inadequate, or have been compromised…These situations may or may not result in injury. They include”near misses”�.

The concept of entrapment applies equally in the structural firefighting environment. I read news accounts of extreme fire behavior related events (e.g., flashover, backdraft) from around the United States on a weekly basis. Flashover, backdraft, or other extreme fire behavior often results in a near miss or minor injury and less frequently in serious injury or fatality. Some (actually very few) of these incidents are documented in the National Firefighter Near Miss Program. As discussed in my last post, the near miss program uses self-reported data. This is extremely useful in determining the individual’s perception of the event and what lessons they took away from the experience. However, the individual reporting the event may or may not have the training or education to recognize what actually happened, determine multiple causal factors, and provide a reasonably objective analysis.

Formal Investigation

If a significant injury occurs, some level of investigation is likely to take place (even if it is limited to a cursory examination of circumstances and conditions by the individual’s supervisor). Traumatic fatalities result in more significant and in many cases multiple investigations by the agency involved, law enforcement agencies, Occupational Safety and Health Administration (state or federal), and potentially the National Institute for Occupational Safety and Health (NIOSH). The purpose of these various investigations is different and not all focus on identifying lessons learned and opportunities for improving organizational performance. However, some reports by the agencies involved, state fire service agencies, and NIOSH take positive steps in this direction. For example:

• Prince William County (Virginia) Department of Fire & Rescue
  Line of Duty Death (LODD) Report for Technician I Kyle Robert Wilson
• Texas State Fire Marshal’s LODD Investigation Program
• New Jersey Division of Fire and Life Safety Firefighter Fatality and Serious Injury Report Series
• NIOSH Fire Fighter Fatality Investigation and Prevention Program

Limitations

Near miss events and events involving extreme fire behavior resulting in minor injuries or damage to equipment frequently are not or are inadequately investigated to identify causal factors and lessons learned. Investigation of serious injuries and fatalities in many cases do not adequately address fire behavior and interrelated human factors that may be directly or indirectly related to the cause of the incident. This results in lost opportunities for individual and organizational learning.

Two interrelated challenges make investigating extreme fire behavior events or structural fire entrapments difficult. First is the lack of a formal process or framework for this specific type of investigation and second is potential for investigators lack of specific technical expertise in the area of fire behavior.

A Solution

The US Forest Service uses a team approach to investigating entrapment incidents. The team may include (but is not limited to):

• Fire Operations Specialist (Operations Section Chief level)
• Fire Safety Officer
• Fire Behavior Analyst, with experience in the incident fuel type
• Fire Weather Meteorologist
• Fire Equipment Specialists who develop the personal protective equipment (including fire shelters) used on wildland fires
• Technical Photographer
• Fire Information Officer

This team is established and begins the investigation as soon as possible after the occurrence of the event to ensure that critical information and evidence is not lost. The investigative process and documentation focuses on accurately describing what happened, when it happened, causal and contributing factors, and recommendations to reduce the risk of future occurrence.

What might this look like in the structural firefighting environment?

Communicating Lessons Learned

Lessons learned must be integrated into appropriate training curriculum to ensure that the lessons are built into organizational culture.

Some agencies have taken steps in this direction. Following the line-of-duty death of Technician Kyle Wilson, Prince William County Department of Fire & Rescue conducted an in-depth investigation which integrated use of computational fluid dynamics (CFD) modeling to describe likely fire conditions and the influence of wind on fire behavior. Following the conclusion of this investigation, the report and related presentations have been distributed widely.

Investigating Wildland Fire Entrapments identifies timeliness as being essential in dissemination of the lessons learned. This presents a significant challenge when faced with a complex event involving a major injury or fatality. However, it is likely that timeliness in communicating lessons learned can be improved without compromising the thoroughness and quality of the investigation.

My next post will examine the US Forest Service’s less formal Peer Review Process which may be used following near miss events or significant events regardless of outcome (possibly concurrently with a formal investigation). Like the entrapment investigation procedure, there are likely some lessons here for the structural firefighting community!

Ed Hartin, MS, EFO, MIFireE, CFO

What is the difference between a fairy tale and a firehouse tale?

Fairy tales generally begin with once upon a time, while firehouse tales begin with you wouldn’t believe what happened last shift and no, this really happened. This post begins with a firehouse tale.

A crew of firefighters advances a 1 1/2″ (45 mm) hoseline up a stairwell in a large wood frame house. The second floor is well involved, and the smoke level is down close to the floor. The young firefighter with the nozzle indicates that it is too hot to advance onto the fire floor. The officer moves up close to the nozzle and evaluates conditions, finding that the firefighter is correct. The officer calls the incident commander and asks for ventilation to raise the smoke level and relieve some of the heat that is preventing advancement onto the fire floor and an attack on the fire. Moments later, the officer is enveloped in fire and feels himself flying backward through the air. This ends when he slams into a hard surface. Everything is black, and he is unable to see. It is not hot, and eventually, he sees a glimmer of sunlight. Attempting to remove his breathing apparatus facepiece, he experiences discomfort in both shoulders, but is able to pull the facepiece off, discovering that the darkness was caused by blackening of the exterior of his facepiece lens. The building is still well involved, the hoseline extended through the front door, but the crew of firefighters that was with the officer are nowhere to be seen. The officer pulls his facepiece back on and crawls back in along the hoseline, finding the firefighters frantically trying to make the fire floor, thinking that their officer had been blown down the hallway instead of up and over their heads, balling down the stairwell behind them and rolling out into the street. The officer withdraws his crew as other crews extend hoselines to the second floor, and extinguish the fire.

In this incident, the officer with the hoseline was unaware that significant indicators of a potential backdraft in an enclosed section of the second floor were visible from the rear of the structure (where the incident commander and the crew performing horizontal ventilation were located). The effects of the backdraft were serous but could have been much worse. The officer received minor burns, injured both shoulders, and severely damaged his facepiece and turnout coat. What made this incident worse was that it occurred during live fire training with a group of recruit firefighters.

I know that this firehouse tale really did happen as I was the officer in the story. This incident occurred in the late 1970s while I was working for the Massachusetts Firefighting Academy as a part-time instructor. Unfortunately, while academy staff investigated this incident, the outcome of this investigation did not impact substantively on training practices, and at the time, the academy staff did not widely communicate lessons learned.

How many of you have had a close encounter with extreme fire behavior? One where you said that was close or you suffered a minor injury? What did you learn and how did you share this information?

Often, as in this backdraft incident, those involved learn a valuable lesson, but do not share the information beyond the firefighters and officers they work with. Many things have changed since the 1970s. One is the existence of National Fire Protection Association 1403 Standard on Live Fire Training Evolutions. While not perfect (but that is another topic for discussion), it identifies systems of work that increase the safety of participants engaged in live fire training. Another, more recent change was the development of the National Firefighter Near Miss Reporting System. This system leverages the advantage of the World Wide Web to provide the ability to report near miss incidents and widely share our lessons learned. If you have been involved in or witnessed a near miss incident or have been told of the event, you can anonymously submit a report and share what you have learned.

The data submitted to the Near Miss Reporting System does not go into a vacuum. Following review, and removal of information which would identify the agency involved, reports are posted in a searchable database on the firefighternearmiss.com website.

This program is a tremendous resource! Visit the site and search on flashover (38 reports), backdraft (9 reports), rapid fire progress (4 reports), or smoke explosion (33 reports). Remember, this database contains self-reported information. This does not make it less useful. In many ways it is more useful than distilled and analyzed information presented in other types of reports (particularly when the individual was involved in or witnessed the event). However, there may be technical inaccuracies (particularly with regards to extreme fire behavior phenomena) and the lessons learned by the individual who submitted the report may or may not be what you want to take away. Read the reports, think about the factors that influenced the occurrence of the event, how it could have been prevented, trapped or mitigated, and draw your own conclusions.

If you are involved in, witness, or are told about a near miss event, report it. The more information in the database, the greater the potential to identify patterns of causal factors and develop strategies for improving firefighter safety.

Ed Hartin, MS, EFO, MIFireE, CFO