Leadership

Wind-Driven Structure Fires: Adjusting Tactics and Strategies

Issue 5 and Volume 164.

BY KRISS GARCIA

Trying to combat the hazards associated with wind-driven fires can be alarming for firefighters. But, wind is nothing new; it has been with us from the beginning of time. It was around as many as 30 years ago when many of us started in the fire service. Why then does it seem like such a new and complex problem? The key is to work with, not against, Mother Nature. Structural firefighters, wildland firefighters, and hazardous materials professionals have learned to adjust to and modify their tactics and strategies to work successfully when winds are prevalent. One of the earliest appreciated records of this is described in the recently released book The Big Burn by Timothy Egan. It reflects on of the largest wildland fires in U.S. history during which weather and the associated wind was used to accurately predict fire behavior, saving thousands of individuals. Early firefighters such as Ed Pulaski, one of the first U.S. Forest Service wildland firefighters, appreciated and used Mother Nature to predict fire behavior.

Likewise, if wind wants a hazardous material to move from one place to another, efforts are made to get to the windward or anchor side of the event and seek weather predictions to assist us in minimizing life safety risks associated with working on the leeward side of an immediately dangerous to life and health (IDLH) atmosphere. In both wildland and hazardous materials incidents, we would never think about trying to work against Mother Nature. Instead, we modify our approach and choose a position or make a tactical anchor to ensure that predicted wind conditions are used to support our safe mitigation of the event.

I think back to my early years in the service when our gear was not nearly as formidable as it is today. We would never have considered placing firefighters on the leeward side of any fire. Yet even with today’s superior gear, we are still protected from conditions related to being on the wrong side of a wind-driven event for only mere seconds. Because of this, we have to make sure our mitigation strategies consider wind direction and wind speed as well as the unexpected breaching or opening of interior doors. Again, attacks anchored from the windward side of the fire make this more likely.

SIZE-UP

If Mother Nature wants a fire, whether it is in the wildland or structure arena or a high-rise or a single-family dwelling, to burn in a given direction, that is the way the fire will travel. In “Wind-Driven Fire Research: Hazards and Tactics” (Fire Engineering, March 2010), Daniel Madrzykowski of the National Institute of Standards and Technology (NIST) and Stephen Kerber of Underwriters Laboratories stated that winds of between 10 and 20 miles per hour can cause substantial wind-driven fire behavior.

When we get into trouble during wind-driven fires, it is because one of two scenarios have played out. The first is that we don’t recognize that there is sufficient wind to affect the fire. Without this recognition, it is hard to make appropriate tactical decisions. The second scenario involves thinking that we can beat or control Mother Nature. This has never been successful and will never be as successful as appreciating and working in coordination with her.

When fighting fires in conditions where the wind is substantial enough to affect fire behavior, the surest way to put firefighters into the direct path of lethal energy is to launch an attack from the leeward side of the fire. The surest way to keep firefighters in a clear and ever-clearing environment is to ensure ample exhaust on the leeward side of the fire as we anchor our coordinated suppression efforts on the windward side.

If unpredictable wind is apparent or if we cannot attack from the anchor, we should appreciate these unpredictable conditions and make necessary and thoughtful mitigation decisions that take into account the fact that conditions may change and we may be in the downwind lethal flow of products of combustion.

Wildland vs. Structural Fires

When trying to analyze a complex problem such as wind-driven fires, I look back to the basics of fire behavior for answers. In doing this for wind-driven fires, it was natural to compare how wildland and structure fires are fought. The more I looked, the more similarities, instead of differences, I found. In the wildland event, general tactics are that we should get to or make an anchor and attack the fire using the wind as an ally, not as a foe. If we cannot make our way to the anchor, we then try to anchor and attack from a more windward flank.

Without exception, we do not move ahead of the fire unless a risk-benefit analysis has been done and our resources are substantial. Using this analysis of wildland vs. structure fires, I also considered the shortest and, when used, most successful tactical priority of LCES (Lookouts, Communication, Escape Routes, and Safety Zones). One of the surest ways to stay safe in the wildland arena is to follow this acronym.

Carrying this analysis further, how then does this relate to structural firefighting?

First, Lookouts should be posted to help ensure that all factors affecting our firefight are being observed and reacted to. In the structural fire discipline, we may call these individuals group and division supervisors, safety officers, or incident commanders (ICs). Regardless of what you call them, they are still Lookouts.

When considering Communications, maintain open communications. That means setting up or organizing incidents correctly and using feedback to confirm that geographical (divisional) assignments and objectives (groups) are clearly understood. After this, keep the radio as quiet as possible so crews can go to work without constantly having to listen to or participate in radio chatter. In the IDLH portion of a firefight, limit communications to messages that will immediately and directly make the incident smaller or enhance control. Well-run fires are generally quiet fires with limited radio communications because the fire was set up well.

I remember an early-morning fire in a nonsprinklered three-story building of ordinary construction; a new officer was continually giving me progress reports, so much so that there was no airtime for anyone else. One of the senior officers later told him, “You have four of the finest firefighters we have with you and several million dollars of apparatus to support you. You should be making progress. Now, shut up, go to work, and tell us when you can’t do your job, and we will help.”

You can relate this to station life by looking at mealtime. During the preparation of the meal, kitchens are noisy, and assignments are made. Once everyone understands and accepts their objective, the table gets quiet, and everyone goes to work eating. After a well-communicated assignment, the only communication coming from a tactical position should be either “I have completed my assignment,” “I can’t complete my assignment (explain what you need so that you can),” or “There has been a major development.”

When considering Escape Routes and Safety Zones in the structural event, operating from the windward anchor assists crews in making sure they can safely make their way to Safety Zones, which most of the time are outside or in protected structural areas such as stairways. Escape Routes and Safety Zones are much more tenuous and uncertain if on the leeward side of a fire. In fact, it may be nearly impossible to ensure these Escape Routes and Safety Zones will be available when crews are on the leeward side of the fire.

Why then do we think that, given a structure fire that is burning with four to five times more energy than the ordinary combustible fuels of a wildland fire, we can successfully fight against Mother Nature? What we do know is that wind will move the IDLH atmosphere through the building from the windward side and help to ventilate this IDLH and often explosive environment out of the building on the leeward side. When considering this explosive and often unpredictable environment, a sage old chief once told me, “Fire is not scary. Smoke is scary. Get rid of the smoke, and go put the fire out.”

SEEKING INTELLIGENCE

“In reality, predicting the wind factor on the fireground is more an art than a science. Wind direction and velocity can change dramatically and without warning, even when atmospheric conditions are not changing significantly,” states a book on high-rise buildings. If the flames are freely exhausting out of the leeward window, a windward-to-leeward path of travel has most likely been established, and if we can make our way to the windward or anchor side of the fire, a predictable interior attack can be made. If the flames are pulsing out of or being forced back into the window on the windward side of the fire, then a sufficient exhaust corridor has not yet been created. Until a windward-to-leeward flow path has been established, conditions may not be favorable for interior firefighting.

The Fire Department of New York (FDNY)/NIST study demonstrated that even if flames are being forced out of adjacent windows in the fire apartment with a high amount of energy, there could still be sufficient energy flows on the fire floor to create a hazard for firefighters. For this reason, as well as the unpredictable timing of breaching interior doors, you can improve the safety of the crew by trying to ensure an anchor with a coordinated positive pressure attack, and controlling the energy from a safe position from the anchor side of the fire may prove to be the safest and most predictable fire attack. Securing your own anchor through the windward placement of a high-powered gasoline-fueled fan will aid in ensuring that you have anchored the fire correctly. This obviously is when ample exhaust is present.

You must also be disciplined enough in your fire attack to control the door. Door control is the most basic means for interrupting or controlling the flow path in the building. Check the fire floor stair door for heat and hot gases flowing around the edges before attempting to open it. Never open a space without the ability to control it. Attach a strap to all inward-opening doors before opening them. Initially, open the door only a few inches to check for rapid changes in smoke volume or velocity and thermal conditions. If the thermal environment changes quickly, close the door to interrupt the flow path. Use a similar approach on all doors that need to be opened as you make your way to the fire. When opening an interior door with fire on the other side, the pressure within that area will force those products of combustion into the area in which you are located. Control of this interior door is absolutely necessary.

One of the best ways to determine what the wind will do in the multistory fire resistive apartment building when a window fails is to assign a member to the interior of the apartment directly above the fire apartment. Once there, this person should open a window directly above the fire apartment and keep the door open in this apartment as well. If wind immediately blows into this apartment, transmit this information to the IC and the supervisors on the fire floor. Wind blowing through the apartment above indicates that wind will also blow into the fire apartment if a window is compromised.

This phenomenon is not isolated to high-rise structures. You need only to look at the fire in Houston, Texas, last year that claimed the lives of Firefighters James Harlow and Damien Hobbs and the Kyle Wilson line-of-duty death in Prince William County, Maryland, to see how wind affects residential fires. Confirmation regarding wind direction can easily be determined at the vast majority of fires that occur at ground level by looking to the American flag many of us fly on our apparatus. The direction I give my officers for a low-rise structure is this: The firefight should always be from the star side of the flag and move in the direction of the stripes. If you cannot do this, then it may be best to start your attack from the windward flank side of the structure.

If you measure wind speed at ground level, you can expect about one and a half times the wind speed 30 feet up. At 120 feet above the ground, wind speed will be twice what it is at ground level. If you do not have a wind gauge, you can get a rough idea of wind speed from the North Coast Power (Cazadero, CA) table below:

ASSIGNING TACTICS

Regarding battle or war, General H. Norman Schwarzkopf stated, “You go to war with what you have.” Regarding wind, how then do we determine what we have working for and against us? How do we use Mother Nature as an ally? For this, I once again look at the wildland battlefield for similarities. Whenever these firefighters are going to be operating at a fire where wind will be a factor, great lengths are taken to make sure everyone who may be called to fight a fire is made aware of the predicted dangers. If we can predict a hazard, we can prevent it. Why not carry those same weather alerts into the structural fire discipline? These reports enable us to immediately modify our structure tactics and help increase our appreciation of the need to work with Mother Nature if our firefighters are to be successful.

Instead of putting our efforts into trying to beat Mother Nature, we should alter our tactics to work with her. Deploying a fire resistive blanket or a wind-control device can be very effective, but take into account only one window at a time. If other windows on the windward side also fail, conditions may change so rapidly for interior crews that you may not be able to deploy additional devices in time. To ensure an escape route over a window that has failed on the windward side of a fire has demonstrable benefit. According to Dan Madrzykowski of NIST, “This tactic should only be used and firefighters should be deployed above the fire only in fire resistive construction.” For many of us, this tactic, while effective, may be too labor intensive to deploy. With that assumption made, the risk-benefit analysis says we should slow down and attempt to limit firefighter hazards by making sure our tactical operations support attacking from the windward anchor or at least the windward flank of the fire.

The floor-below high-rise nozzle also tested by FDNY seems to have great promise and supports a tactically appropriate windward/leeward operation. In their Fire Engineering article, Madrzykowski and Kerber state: “In all cases, the water flows from these nozzles suppressed the fires, thereby causing reductions of at least 50 percent in temperature in the corridor and the stairwell.” With this tactic, windward attacks are supported, and the operation takes place from the generally safer position below the fire rather than above it.

OVERHAULING THE PROBLEM

Consider the orders and objectives made during the structural fire identifying the anchor side of the fire. Nothing other than traditional practice says the address side of the fire is the A side. The A side could just as easily be the windward or anchor side of the fire. Regardless of the velocity of the wind, make any interior attack from the windward or anchor side of the fire. Whether or not there is any appreciable wind, I would opt to bring my own wind or horse power with me and securely anchor the fire with a high-power fan knowing that studies, including those by NIST, have confirmed that with proper exhausting, the use of a fan increases the tenability of survivable areas in the fire structure. In effect, I am making the firefight safer for my firefighters by making sure the fire is anchored, and I am increasing the tenability of the interior while at the same time ensuring that my firefighters can see the hazards they are operating with so that they can adjust to them. If conditions change during the fire operation and doors are breached or winds shift, having a fan at our back at least gives us more of an opportunity to remain in a clear environment while we adjust to changing conditions.

Working with Mother Nature ensures the highest level of safety for our firefighters. Operating from a secure anchor that allows the IDLH environment to be removed from the building so firefighters’ escape routes and safety zones can be ensured is a must. A hazard seen is a hazard avoided. A hazard predicted is a hazard prevented. Fire is not scary. Once we see the fire, the battle is about over. Smoke is scary, and regardless of your skills at reading it, it is unpredictable and often reacts with aggressive behavior that compromises firefighter safety.

KRISS GARCIA, who has served in the fire service for 25 years, retired as a battalion chief from the Salt Lake City (UT) Fire Department and is now chief of American Fork (UT) Fire and Rescue. He has a bachelor’s degree in public administration, is a licensed engineering contractor and a paramedic, and is an NFA Instructor. He serves on the NFPA 1021 committee and is a voting member of the Air Movement Control Association. His interest in positive-pressure ventilation and positive-pressure attack began in 1989. He coauthored, with Reinhard Kauffmann, Positive Pressure Attack for Ventilation & Firefighting.

More Fire Engineering Issue Articles
Fire Engineering Archives