Part of the allure of the fire service is that, as the definition implies, we are often powerfully and mysteriously attracted or fascinated by things that we witness in this job. Many years ago, I responded to a grass fire on a very windy day and was driving the first-in engine. On arrival, I found a fire in a horse pasture. As I slowed to evaluate the best access, I couldn’t help but notice that the fire was moving faster than my engine. I then witnessed a pair of horses galloping parallel to the roadway with the fire moving faster than they were. The horses, fueled by their self-preservation, turned sharply and headed perpendicular to the roadway to the back of the pasture, narrowly escaping the rapidly moving fire. That was the first time I had ever witnessed a wildland fire moving faster than a horse can run. Although I was “powerfully and mysteriously fascinated,” I was also terrified, thinking that I needed far more than my single engine at this fire.
Wildland fires are not a new type of incident to which we respond. However, they can be extremely challenging. Those of you that work in a predominantly urban environment may not be as concerned as those that have a significant wildland/urban interface or those from rural departments. Here’s the thing, though. It is the urban departments that are often called upon to assist when the “big one” hits. Even if you work on a four-person engine in an urban environment and your first-due area only has four blades of grass in it, you have to be prepared to deal with wildland fires that may occur far from your station. We must all be prepared, and that requires an understanding of wildland fires, our friends, forestry, fuel, and foes.
First, let’s examine our friends. Our typical response to a wildland fire involves one engine. Upon arrival, if the fire is small enough, the engine will extinguish the fire and return to quarters. Sometimes, the fire will be inaccessible by hose lines, thick subsurface (“duff”) burning, or the fire is otherwise too big to extinguish. Enter our friends from the Forestry Service. Typically, our Forestry friends will bring a bulldozer towing a plow to cut lines around the wildland fire to confine it and keep it from spreading further. When this occurs, our role is simply to protect any fixed or mobile property (buildings and vehicles). However, when there are multiple homes threatened simultaneously, we will need more than one engine. Likewise, when a single plowed line is insufficient to confine and contain a wildland fire, more than one dozer/plow may be needed. For these escalated incidents, it is important to recognize two facts. The state Forestry Service likely operates on a budget that is less than what most medium and large fire departments get annually. The second fact is that while we can call upon our neighboring fire department friends to assist us with additional engines and tenders, there are not a whole lot of agencies that maintain forestry dozers with plows and, more importantly, trained operators. The result of this is that we may have to wait more than we would like for the first dozer/plow to arrive and that operators may have to wait more than they would like for any additional dozers/plows to arrive. This is something we have to keep in mind when we arrive on the scene and think we need additional resources. Request your friends and forestry early, as it will likely take them a while to get to you.
Next, let’s consider parts of wildland fire and the fuel. Of course, where the fire started is the origin, the heel is the back, and where the fire is going is the head. The left and right flanks are to the left and right of the head, respectively. Fingers are narrow strips extending from the main fire. The “green” is any unburned area, and the “black” is any burned area. Although we often think of “the black” as being a safe area, it is an area of concern as burning snags, standing dead trees, and downed trees may pose a hazard to those operating in the terrain, particularly if it is steep. Spot fires occur when heat and embers in front of the fire’s head ignite fuels prior to the main body or head of the fire arriving. When spot fires occur, it suggests that the head of the fire will soon arrive and that the fire is moving quickly. When it comes to fuel, there are more or less four kinds, subsurface, surface, ladder, and aerial fuels. Subsurface fuels, when thick enough, can actually allow a fire to spread underneath a plowed dozer line. If you have access to a drone with a FLIR camera on it, or your “friend” does, it can help determine where the hot spots in subsurface fuels may be, as they may not be emanating much smoke. Surface fuels are those that contribute to the most fire spread. They can range from short grass to thick bushes and trees. Very thick surface fuels often prevent access with hose lines and require a dozer/plow to penetrate them. Ladder fuels are taller bushes, shorter trees, or vines that allow the fire to spread from the surface fuels to the aerial fuels. Ladder fuels may be inaccessible by hose lines, and unless they can be knocked down by dozers, they will be difficult to extinguish. Finally, we have aerial fuels, which are often seen as the crowns of trees. When a fire originates in a surface fuel and spreads to aerial fuels by way of ladder fuels, there is really only one option, get out of the way. The fire that is crowning through the treetops is not affected by extinguishing or plowing the surface fuels below it. A lot of attention should be paid to any units reporting a crowning fire. Assigning resources to any homes in front of the head of a crowning fire should be a priority if the environment is safe enough to do so.
When operating at a wildland fire, there are a couple of basic safety precautions aside from, but related to, the National Wildfire Coordinating Group 10 Standard Firefighting Orders. If you are operating an engine at a wildland fire, you should attempt to back your engine into your area of operations. It is easier to evacuate by selecting “D” on the apparatus transmission than it is by selecting “R” on the transmission. Attempting to back out/reverse during an evacuation may result in the apparatus becoming stuck or involved in a collision. This puts the apparatus and crew at risk of being overrun by the fire. Keep all apparatus doors closed and windows up. A stray ember from a spot fire or head can land inside the apparatus cab and ignite the combustible interior. If you are busy fighting a large wildland fire, you probably don’t want to take a break to put out the apparatus you rode thereon. Finally, you should keep hose lines as short as possible. Long attack hose lays are difficult to pick up in a hurry, should an evacuation become necessary. Moving the apparatus and keeping your hose lays short will allow you to throw the hose on the apparatus and move faster if you need to.
This brings us to our foes. The first National Wildfire Coordinating Group 10 Standard Firefighting Order is “Keep informed on fire weather conditions and forecasts.” There are a number of things we need to consider. The first is wind speed and direction, which will determine which way the fire is going to move and how fast. Next, we need to consider relative humidity (RH) levels. RH is typically highest overnight and begins to drop after the sun comes up, with the lowest level usually occurring in the early afternoon. RH is a measure of moisture in the air. The more moisture in the air, the less likely that our fuels can lose their moisture through evaporation. If the RH is 100%, the air is saturated with moisture, which means the fuels will be saturated with moisture as well. When the RH drops significantly, moisture in our fuels can readily evaporate into the air, leaving them primed to burn. In fact, when the RH gets in the teens or single digits, our fuels can very rapidly burn, making fire spread much more difficult to control. Finally, we need to consider fronts and storms. In the northern hemisphere, low-pressure fronts spin counterclockwise, and high-pressure fronts spin clockwise. Remember that wind direction is determined by evaluating from which direction the wind is coming, not which way it is going. In other words, if you are looking north and the wind is hitting you in the face, then that is a north wind. Even though it is blowing to the south, it is coming from the north, and that is how our National Weather Service friends will report the direction. If a low-pressure front is passing south to north over your wildland fire, you will likely experience easterly winds before it passes and westerly winds after it passes. Storms can produce outflow boundaries, rapid acceleration of wind speed, and changes in wind direction. Ask any weather forecaster, and they will tell you those forecast models do well until the first thunderstorm cell develops. Like billiard balls on a pool table, storm cells can push winds that collide with other cells that change direction and collide with another cell, and so on. Storms also have the potential to produce lightning, which is a threat to our personnel. In open land, our firefighters may be the tallest objects and run the risk of being struck. In dense woods, they may be standing underneath the tallest tree around and may again run the risk of being struck (if the tree they are standing under is hit). Storms will generally signal the end of firefighting efforts at wildland fires as the risk of lightning and erratic fire behavior, as a result of the wind speed and direction changes, require a moment of pause to re-evaluate your current tactics and ensure that our people are properly protected. With a little luck, the storms will bring some heavy rainfall that will help to knock down the fire and saturate any surrounding unburned fuels.
Wildland fires can be simple 15-minute calls or can last for days or weeks. Everyone, including firefighters in urban areas, should be prepared to respond to and operate at wildland fires. Remember where your friends are and what they can bring to the fight. Contact forestry early, consider the fuels involved, and constantly monitor our weather foes so that you can properly protect our firefighters.
Be safe and do good.
David Greene has over 31 years of experience in the fire service and is currently the deputy chief with Colleton County (S.C.) Fire-Rescue. He holds a PhD in Fire and Emergency Management Administration from Oklahoma State University and an MBA degree from the University of South Carolina. He is a certified Executive Fire Officer through the National Fire Academy, holds the Chief Fire Officer Designation from the Center for Public Safety Excellence, holds Member Grade in the Institution of Fire Engineers, is an adjunct instructor for the South Carolina Fire Academy and is a Nationally Registered Paramedic. He can be reached at firstname.lastname@example.org.