Initial Attack in the Wildland Urban Interface

Many firefighters lack direct experiential “slides” of a fire not being contained



By Kevin Cashman | Fire Engineering

For a century, America has faced a nonstop conflict against wildfire. The struggle has ebbed and flowed, and strategies have evolved, but every year there is smoke on the horizon and flames in our backwoods. Municipal firefighters are no doubt positioned at the front lines of this conflict, as the following grim statistic demonstrates: Of the 209 firefighters killed as the result of wildfires between 2001 and 2015, 73 were from career or volunteer fire departments.1 Wildfires are dangerous for firefighters from all agencies. In 2018, 40 percent of all fireground deaths in the United States were at wildfire incidents.2

The place where this conflict is most severe and where the stakes are the highest is in the wildland urban interface (WUI). Arguably, the initial attack (IA) is the operational phase in which firefighters face the greatest risk in suppressing wildfires. This article focuses on the overlap of these two elements and how their unique risk profiles intensify wildfire hazards. Regardless of what the fire season is doing today, the challenges of IA in the WUI are here to stay. Imbedded directly in this environment are firefighters from federal, state, county, and city fire protection agencies who are in the mix every time the radio tone goes off.

Houses, Trees, and WUI Challenges

The WUI encompasses a broad jurisdictional conglomerate of federal, state, and privately owned lands. But, regardless of who owns the land, it is the Values at Risk (the residential and commercial buildings and supporting infrastructure) that give the WUI environment its unique profile. When you add in the legitimate risk to civilian lives, the WUI gets some needed consideration from folks in the greater American fire service.

To risk saying the obvious, it must be stated clearly that, to the general public, buildings on fire in a neighborhood are a bigger deal than trees on fire in a wilderness area. Fire management decisions at the national level reflect this. One need only to look at how national usage priorities for the very large air tankers (VLATs) are determined. The wildfires chosen for coverage by national media outlets and the wildfires governors and presidents make appearances at are other examples of how WUI fires rank in the public’s mind.

(1) Rapidly growing IAs can quickly threaten many values at risk in the WUI. Point protection of evacuated structures is initiated when safety zones are near. (Photos by Mike Reese.)

For the frontline firefighter, fires burning around, into, and inside the WUI present extra challenges. The primary challenge seems clear: With lives and property under threat, firefighters will take more risks during WUI fire suppression. The reason to stretch to the limit of our comfort level is arguably justified. And, it is riskier. From the Carr Fire in 2018 to the Twisp Fire in 2015 to the Esperanza Fire in 2006, experienced and courageous firefighters assigned to WUI operations were confronted with rapidly intensifying fire behavior that outpaced their risk mitigation measures and their fire behavior predictions.3-4 The well-versed firefighters at these incidents made strategic and tactical suppression decisions in large part based on the proximity of civilian lives and property to the fire hazards. In other words, being in the WUI environment influenced how they decided to fight the fire, and firefighter death was the tragic outcome.

Line Placement

Time and time again in the WUI, decisions on where to place direct or indirect control lines are guided by the locations of buildings and infrastructure. We choose where to cut our line so that lives and structures are protected, which is great. But, this fact occasionally results in suboptimal line placement; suboptimal timing; and slower line production rates with regard to topography, fuels, and rate of fire spread. This isn’t a bad thing; it’s just reality. Things are rarely optimal in the field, and first responders across all public safety dimensions are prepared for that. That said, I would argue that it’s important for firefighters to remain aware of factors in the fire environment that are complicating our decision processes. If houses weren’t in the picture, the control line would be put in locations better suited for fire containment. But, of course, the houses are in the WUI, and firefighters adapt to the situation.

Strategic Options Decreased

WUI fires up the ante for firefighters, and they simultaneously decrease the strategic options available to incident command staff. For example, I have never heard of a “Wildfire Use” or “Multiple Objective” management strategy being employed in the WUI environment—and for good reason. These strategies in which wildfires are more or less left to burn naturally in isolated wilderness areas are an excellent and wise option given the correct conditions. For obvious reasons, these strategic options are off the table when the fire threatens lives and property. Full suppression becomes the only option.

Backfiring is another commonly used and effective strategy that is hamstrung when civilian lives and property are intermixed with wildfire. This is an indirect strategy with many benefits; but, if used in the WUI, it is best if there is a greater depth of planning and staffing than when backfires are employed on “traditional” wildfires burning in a forest without buildings or people. It’s one thing when a firing operation doesn’t go as planned and the escaped fire ignites more trees and brush than desired. It’s another thing entirely when a firing operation fails and a neighborhood is lost. That said, when executed by elite wildfire fighters in a thorough manner,5 backfiring remains a powerful tool for combating large-scale WUI fires.

(2) Threats to infrastructure are par for the course during WUI IA. Odd hazards can be created as a result. (3) Firefighters need to recognize when a WUI IA is becoming an extended attack incident.

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Houses as Fuel

The Waldo Canyon Fire in 2012, the third most destructive wildfire in Colorado history, presented an unusual, but previously seen, fire spread phenomenon—Fuel Model “House.” In the foothills outside of Colorado Springs, the Waldo Canyon Fire impacted the densely spaced Mountain Shadows subdivision and, in combination with adverse winds, burned 344 homes in one night. The burning homes, themselves, provided the primary fuel that carried the fire through the subdivision.6

The takeaway for a frontline firefighter here would be that even if an area doesn’t have a large loading of traditional wildland fuels, once engulfed, the houses, themselves, can create severe containment difficulties and enable the fire to spread significantly. Frontline wildland firefighters should include this unusual fuel type in future neighborhood triage assessments.

IA in the WUI

The IA is another problematic aspect of wildfire suppression within this context. For the sake of accurate jargon, an IA fire is defined as a “fire that is generally contained by the attack units first dispatched, without a significant augmentation of reinforcements, within two hours after initial attack, and full control is expected within the first burning period.”7

The top concern involving wildfire IA is that the IA is the most common operation where entrapments occur for fighters tasked with wildfire suppression.8-9 Let’s define the term entrapment because it’s important. Entrapment is “a situation where personnel are unexpectedly caught in a fire behavior-related, life-threatening position where planned escape routes or safety zones are absent, inadequate, or compromised. An entrapment may or may not include deployment of a fire shelter for its intended purpose. These situations may or may not result in injury. They include ‘near misses.’”10

Although unique factors contribute to every entrapment, it is fair to make some general presumptions as to why IA operations create the majority of entrapments. We are a “go-getter” culture, so firefighters have a strong internal drive to arrive first on scene. That said, let’s consider that first-arriving units during IA are often going into the unknown. This is part of the fun but also part of the danger. Where is the fire? What is it doing? What are the fuels? What are the weather and topography in the area? How can you apply your training to make things better? These are questions firefighters love to answer.

In general, before suppression resources arrive and stabilize a wildfire incident, the fire is at peak “chaos.” Most of the time, that chaos is small and well within the IA units’ ability to control. But, sometimes it is not. Sometimes conditions are ripe for a rapid rate of spread and the chaos outstrips the firefighters’ ability to contain the fire and, more importantly, employ adequate risk-mitigation measures. This is when the probability of entrapment creeps upward. Simply put, IA tends to be more dynamic and unpredictable than extended attack (EA) and prescription burns, and firefighters are entrapped more as a result.

It’s good to recognize another data point regarding IA: The vast majority of wildfires are caught during IA—98.5 percent to be exact, according to the Wildfire Lessons Learned Center.11 This is a testament to the good work done by our fellow firefighters over time. It also implies something we all know: Not all IA wildfires are made the same. Many are straightforward creeping 1⁄10- to ¼-acre fires; others skirt the border of being nearly uncatchable by IA resources during extreme wildfire conditions. Some are never caught by first-due firefighters, as 1.5 percent of all IAs turn into EA wildfire incidents.

One final technical definition: An EA incident is defined by the National Wildfire Coordinating Group as “an incident that exceeds the capability of the initial attack resources and/or organization to successfully manage the incident to conclusion.”12

When the Fire Is Not Contained Quickly

One potentially negative effect of wildland firefighters’ success during IA is that many firefighters lack direct experiential “slides” of a fire not being contained within the first few hours. This means that most firefighters have never been present during the transition from an IA incident to an EA incident. Our successes have created a blind spot in our effectiveness.

Why is this a big deal? Let’s refer to the good work by Matt Holmstrom, superintendent, Lewis and Clark Interagency Hotshot Crew, U.S. Forest Service. In his article “Common Denominators on Tragedy Fires—Updated for a New (Human) Fire Environment,”13 he discusses repeating patterns across multiple wildfires where death or serious injury has occurred. Every wildland firefighter should read this article. Holstrom’s common denominator is “IA to Extended Attack Transitions.” He presents seven examples of tragic wildfires where firefighters escalated risk and were too slow to adapt to the changing situation as the fire evolved from an IA to an EA incident.

The firefighters at these incidents were strategically and tactically stuck in the mentality of IA when the fire behavior and growth potential called for something else entirely. We are all susceptible to the symptoms of “Target Fixation” and “Loss Aversion.” We want our plan to win. We don’t want to lose fires. We really don’t want to lose houses. We all want to be good at what we do. There are times (1.5 percent of IAs) when being a good firefighter means recognizing when an incident is growing beyond the scope of IA resources to manage. Recognizing when a wildfire is slipping away is not always easy, and doing this in the WUI is doubly difficult. This is where the challenges of IA and the challenges of the WUI begin to seriously overlap. The main reason for this is that when civilian lives are truly at risk in a rapidly expanding wildfire IA, the stakes are as high as in any situation in our job. In the Camp Fire in 2018, 86 civilians died.14 These incidents are rare, but they do happen, and they have the potential to be very deadly.

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Core Value Adds to Risk

Firefighters are trained and willing to risk their lives to protect and save the lives of others. It is because of this core value that WUI IA becomes the most risk laden. These are just the plain facts of the job. A wildfire slamming into a neighborhood is analogous to a working structure fire with potential victims still inside. During WUI IA, much more than in EA WUI incidents, there is still a high degree of uncertainty as to the exact evacuation status for individual homes. Are folks asleep? Did the wheelchair-bound geriatric resident make it to the car in time? Did the latch key kid playing video games in the basement receive the evacuation notice? Unless it is confirmed that everyone is out, firefighters act under the assumption that people are still in harm’s way.

One common phrase that can cue firefighters arriving at a growing WUI incident that they are possibly witnessing an IA to EA transition comes from line supervisors at the task force and division boss levels: “Go into that neighborhood and see what you can do ….” On one hand, this is an excellent direction from a supervisor because it shows a proactive stance and empowers good firefighters to make a difference and protect values at risk. On the other hand, it also shows that there really isn’t a complete plan in place and that the fire supervisors’ situational awareness could be lower than normal. All of these are things to be aware of. The fire incident is in a high chaos state. Bringing some order to the chaos is the reason we do the job, but we must know the waters in which we are swimming.

Time for Reevaluation

Frontline firefighters should acknowledge “a two-hour time frame,” pulled from the definition of IA: If you haven’t made significant progress and are not moving closer to containment after roughly two hours of aggressive and proper firefighting, then it is time for reevaluation. Fire growth is starting to outstrip resource effectiveness, and this fire might be going toward an EA operation.

It can be difficult to predict fire growth during IA. Winds increasing and aligning with topography are the biggest contributors to increased fire behavior. Good firefighters will leave a sizeable margin of error in their fire behavior predictions in the WUI.15 If you are sizing up the fire accurately, ordering correct resources in proper amounts, and evacuating civilians away from harm, you are winning during rapid-growth IA, regardless of whether you are making progress with containment at that moment.

Things on Our Side

How do we make sense of this information? Fighting fire in the WUI is here to stay, and since the beginning of wildfire fighting, there has been IA. Additionally, firefighters will always do their job of protecting life and property. It is not a stretch to say that the convergence of hazards that occurs when executing IA operations in the WUI creates unique problems for firefighters to solve. Firefighters know this, and knowing is half the battle. Awareness that a hazard exists is the first step in mitigating it. These challenges are by no means beyond the American fire service’s ability to confront and curtail. Let us remember that there are plenty of elements in the WUI that assist our mission and plenty of proactive measures firefighters can take leading up to a fast-moving WUI IA. A few follow.

Usually Quickly Reported

WUI fires are typically reported to 911 dispatch very quickly. Educated civilian eyes are a great asset for early and accurate reporting. The earlier the fire is reported, the better for firefighters.


Access to the seat of WUI fires is typically good. Roads are plentiful; if a fire district is adequately staffed in a geographically intelligent way, arrival to the fire should be rapid. Quick response usually results in fires that remain small, and small fires are the easiest to contain. It is, of course, always recommended that firefighters be highly oriented and familiar with all the nooks and crannies of their response area. Ideally, you should be familiar with and have driven the roads before there is a fire call. Think of a backroad in your response area you’ve never traveled, and drive it. Then, think of how you would fight a wildfire there.


There is a moderately strong correlation between the number of values at risk and the amount of fire protection staffing an area has. The more densely populated an area, the greater the likelihood that the fire district will have strong staffing levels. It goes without saying that correct staffing numbers are vital to successful management of WUI incidents. That said, fire departments throughout the country face the steady challenge of engaging in difficult suppression operations with staffing below National Fire Protection Association recommended standards.16 Nowhere is this low staffing more observed per acre than in rural departments, where the WUI threat is high.

The task list to be accomplished at a large WUI wildfire is long and time sensitive. Without the correct number of personnel, firefighters are less effective at evacuating residents, engaging in fire suppression, protecting houses, coordinating incoming resources, and staying ahead of the fire strategically. Smart and aggressive response with substantial boots-on-the-ground keeps fires small and saves lives and property. If your district is understaffed during the wildfire season, do everything in your power to fix that.

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Time Is on Our Side

I’m not referring to the time we have once the fire starts but the time we have before the fire starts. Preplanning and fuel mitigation are the two best weapons in our arsenal to stem the tide of destructive and deadly WUI fires. Think about it: We get to engage the wildfire on our terms decades before it ignites. This is a massive tactical advantage. This is not a new idea. When a municipal fire district or federal land agency participates in a thorough wildland fuel reduction program and catastrophic wildfire preplan, those firefighters are fighting the fire before it begins, at a pace that is far less dangerous and chaotic. Without a doubt, the lives of civilians and firefighters are saved this way. Isn’t that our primary mission?

When the fire danger is low, fire managers need to use that gift of time to imagine big fire impacting their neighborhoods and to start making plans to improve the worst-case scenarios. If you have a string of homes in your district with no defensible space, help create it. If you have a subdivision under serious future wildfire threat, run civilian evacuation drills for the area.17 If you have a one-way-out neighborhood in your response area with a bad civilian evacuation route, improve that route with fuel thinning. If you don’t have the budget to start a fuel-thinning program, apply for state and federal Mitigation Grants. A “can-do” attitude is essential here. A “must-do” attitude should be right behind it.

Fire managers also have the benefit of years of a head start regarding public education. If your district is in the WUI and there is a relatively frequent wildfire occurrence, it’s a fair bet your citizens know something of the threat. But, it’s imperative for fire managers to educate their public on all aspects including defensible space creation, wildfire evacuations, and ignition prevention. A correctly informed citizenry is a great ally for fire managers, particularly on the topic and execution of evacuations. The public looks to firefighters for answers and for framing the severity of the problem. The majority of citizens want to be proactive in their safety, so give them the chance by providing them with tools to help themselves and, in turn, help us.

It must be said again that fire departments in the WUI that are not implementing some sort of fuel-reduction program, large-incident preplan, and robust public education programs in their districts are seriously underserving their population and seriously reducing their firefighters’ ability to fight fire most effectively. The challenge is great and is outweighed only by the need. When in doubt, start small, but do something. The firefighters at your department 10 years from now will be thankful, not to mention the citizens in your district today. Firefighting in the WUI begins long before ignition.

Get After It, Before and During the Big Day

For many districts across North America, it’s not if but when an envelope pushing WUI fire will occur. In the words of the late Lieutenant Andrew A. Fredericks, Fire Department of New York, “If you put the fire out, you don’t have to jump out the window.” This perfectly drives home the idea of how dialed-in aggressive suppression actions at a structure fire make everything better and can reduce risks to firefighters. I am applying Fredericks’ concept to the topics in this article: There is no place in wildfire more deserving of intelligent and aggressive firefighting and fire planning than IA in the WUI—aggressive studying of the risks of IA in the WUI, aggressive civilian evacuation education programs, aggressive staffing during peak burn season, aggressive fuel reduction programs, aggressive catastrophic wildfire preplans, and smart and aggressive suppression actions on the big day. This is a solid recipe for WUI IA success.


1. “U.S. Firefighter Fatalities Due to Wildland Fires, 2001-2015,” National Fire Protection Association (NFPA) report, June 2016.

2. “Firefighter Fatalities in the US, 2018,” NFPA.

3. CAL Fire Green Sheet, Burn Over Fatalities, Carr Incident July 26, 2018.

4. Esperanza Fire Accident Investigation Factual Report, Oct. 26, 2006.

5. “Hotshots: the Firefighter’s Firefighter,” Fire Engineering, August 2018.

6. “A Case Study of a Community Affected by the Waldo Fire – Event Timeline and Defensive Actions,” National Institute of Standards and Technology Technical Note 1910.


8. “Entrapments by Stage of Fire 1993-2003,” Incident Review Summary, Wildland Fire Lessons Learned Center, 2013.

9. “Single Person Entrapments 1990 – 2015,” Incident Review Summary, Wildfire Lessons Learned Center- 2015.


11. “Two More Chains- Spring 2012,” Wildfire Lessons Learned Center.


13. “Common Denominators Tragedy Fires- Updated,” International Association of Wildfire Fighters, Feb. 2016,

14. “Colossal California Wildfire Finally Contained; Grim Search for Bodies Continues,”, 11/26/18.

15. “Wildland Urban Interface Firefighting,” Incident Response Pocket Guide, April 2018, 12.

16. “Fire Department Staffing: A Need, Not a Want,” Fire Engineering, Aug. 2009.

17. “Civilian Wildfire Evacuation Drills: Worth the Effort,” Fire Engineering, March 2019.

Kevin Cashman is a lieutenant in the Platte Canyon (CO) Fire Protection District. Since 2005, he has fought wildfires across the Intermountain-West for federal and municipal agencies.


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Many firefighters lack direct experiential “slides” of a fire not being contained     By Kevin Cashman | Fire Engineering For a century, America has faced a nonstop conflict against wildfire. The struggle has ebbed and flowed, and strategies have evolved, but every year there is smoke on the horizon and flames in our backwoods. […]

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