Tactical Terminology for the WUI, Part 1

In the fire service, we have more than our fair share of industry-specific acronyms and jargon. Two terms that may seem similar when used in regard to the fire service, but have very different meanings: strategy and tactics. Strategy refers to the general plan firefighters develop in order to accomplish incident objectives, while tactics focus on the specific suppression actions taken on the fireground to fulfill the strategy’s objectives.

Today, structure defense categories and tactical terminology have been developed to create a common language that describes tactical actions intended to put firefighter safety ahead of structure defense assessment. In this article, we’ll examine the actions and categories, as well as the new terminology involved in each.

Structure Triage Categories
FIRESCOPE has adopted key terminology and concepts for three structure triage categories; the California Department of Forestry and Fire Protection (CAL FIRE) has also included these terms in its WUI training curriculum. As a result, it’s crucial that all firefighters–structural and wildland–have a solid understanding of these terms and how they affect fireground operations.

Not Threatened
A not-threatened structure is either out of the path of the fire front or its construction and clearance characteristics are such that the structure is only minimally threatened during fire front impact. These structures have more-than-adequate vegetation clearance and are constructed of fire-safe materials therefore they will require minimal resource commitment and prep work. That said, it’s important to remember to not overlook or neglect structures in this category. Although they’re not necessarily in the fire’s path, they should still be monitored and included in any patrol operation.

Threatened Defensible
A threatened defensible structure has an adequate safety zone or temporary refuge area nearby, but there’s a high probability that the structure will be damaged or destroyed if suppression resources don’t intervene. Structures in this category typically have some degree of clearance from surrounding fuels and limited fire-safe construction features.

Structure defense preparations may include removing fuels, closing windows, covering vents and applying foams or gels to exterior surfaces. Intervention may require that fire department resources remain at the structure during the fire front impact. Residents are usually evacuated, but if they elect to stay, ensure that they understand the situation and are prepared to shelter in place.

Note: If there’s not enough time to perform the necessary defense measures or fire behavior changes adversely, structures classified as threatened defensible may be downgraded into the non-defensible category.

Threatened Non-Defensible
A threatened, non-defensible structure does not have an adequate escape route to a safety zone, nor does it have a temporary refuge area, and based on current and forecasted fire behavior, the structure cannot be safely defended.

Structures in this category typically have little or no clearance from surrounding fuels and exhibit minimal, if any, fire-safe construction features. The structure may be located mid-slope or in another dangerous topographical element, such as a chimney, saddle or drainage. In this situation, civilians must be evacuated from all structures.

Remember: Although the structures initially categorized as threatened, non-defensible may seem like lost causes, structure triage is a dynamic process and any change in the fire environment can quickly alter the defensibility of a given structure at any time. So, a structure categorized as not threatened could be re-categorized as threatened defensible or threatened non-defensible if/when there’s a change in fire behavior.

8 Tactical Actions
There are eight tactical actions used to defend structures in the WUI, three of which are primary tactics and five are secondary tactics. The three primary tactics–check and go; prep and go; and prep and defend–are geared toward defending a single structure and should be used to ensure the correct and safe application of individual secondary tactics. They should also be used throughout the fire progression, even as other secondary tactics are used.

Secondary tactics are more specific and support the goals of the primary tactics, but they generally require more resources, coordination and supervision, and cover a wider operational area. The use of secondary tactics will change throughout the operational period as fire conditions dictate. The five secondary tactics are:

  • Bump and run
  • Fire front following
  • Anchor and hold
  • Connect the dots
  • Tactical patrol

(Note: These tactics will be discussed next month in part 2 of this article.)

Primary Tactics
Check and Go is a rapid evaluation that involves checking a threatened, non-defensible structure for occupants. This tactic is appropriate when fire spread, intensity, time constraints or inadequate defensible space prohibits resources from taking action to defend the structure, and when no safety zone or temporary refuge area exists near the structure.

The evaluation is hasty due to extreme fire behavior and imminent fire impact, meaning evacuation is the primary concern. In some instances, it may be necessary for firefighters to assist with evacuations prior to leaving. If occupants choose not to evacuate, document them and relay the information to a supervisor. Once the fire front passes, firefighters can return for follow-up action.

Important: Only highly mobile resources should be assigned to Check and Go operations. This tactic is not suitable for fire crews or dozers because of the need for tactical mobility and possible rapid withdrawal from the structure site.

Prep and Go is used when it’s not safe for resources to remain at a structure when the fire arrives, but there’s enough time to safely complete limited structure defense preparations before resources leave the area. Again, this tactic is usually used with threatened non-defensible structures.

This tactic is also considered a “quick strike” maneuver where bare minimum structure defense tasks are quickly completed by resources that will not remain at the structure during fire front impact, but may return after the fire front passes. Firefighters should gel or foam threatened structures and evaluate them for follow-up action should additional resources become available, the fire front passes or fire behavior intensity diminishes.

Use Prep and Go when no safety zone or temporary refuge area is available or when fire spread and intensity are too dangerous to stay at the structure during fire front impact. Prep and Go should be considered for defending structures in heavily vegetated areas with minimal clearance, structures located upslope from the fire, and structures located in chimneys and saddles.

Depending on the situation and resource availability, structure prep time will vary so company officers should plan for a hasty retreat. Tip: When implementing the Prep and Go tactic, post lookouts and establish decision points to ensure adequate time for withdrawal.

Resources should contact any occupants at the structure and advise them to evacuate if it’s still safe to do so. Document any civilians who choose to stay at the structure and relay the information to a supervisor.

Prep and Defend is an appropriate tactic to use when a structure is threatened but, based on forecasted fire behavior, will be relatively safe for resources to defend during fire front impact.

Use Prep and Defend when there’s adequate time to safely prepare the structure for defense and access to a safety zone or temporary refuge area has been identified. Firefighters must maintain situational awareness and be prepared to move to the temporary refuge area or withdraw along the escape route to the safety zone when necessary. Firefighters will prepare the structure for defense and stay on site to defend the structure during fire front impact. Again, gel or foam application should be a priority during structure defense preparations.

Tactical Action & Fire Forecasting
An effective tactical action operates on the core principle of agility. All tactical decisions are predicated on the idea that the selected tactics will be successful. The selected tactics must be capable of stopping the fire’s advance or preventing the fire from damaging property and do so without injuring firefighters.

When choosing a tactic or developing a tactical plan, it’s important to try to determine what the fire will be doing at the time firefighters engage it. Although a fire behavior forecast is difficult to make with absolute certainty, it’s crucial when determining whether a tactical plan will be effective and safe. To prepare for changes in the fire forecast, recognize that there’s always the potential for error when making fire behavior forecasts, build alternatives into the incident plan and remain open to alternative plans.

A Note about Tactical Maneuvers
A tactical maneuver builds agility into a tactical plan by allowing resources to work effectively and without injury in a hazardous environment. Tactical maneuvers are most effective when potential changes to the primary plan have been identified and firefighters have an opportunity to pre-plan reactions to those changes. Firefighters must be prepared to utilize a tactical maneuver when changing from structure defense mode (defensive) to perimeter control mode (offensive) when fire behavior allows.

A Final Word
Successful firefighting operations in the WUI are accomplished by developing sound strategies supported by effective tactical actions that keep firefighters safe, protect the public and minimize property loss or damage. Suppressing the fire before it reaches threatened structures is often the most effective way to defend assets at risk, therefore it must remain the focus of resources tasked with structure defense. Firefighters must understand tactical terminology, structure triage categories and structure defense preparation tactics to be safe and effective on any WUI incident.

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