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Unit 10: Fire Behavior Affects Fireline Tactics

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Management   ::  Control Lines  ::   Standards   ::   Attack Planning   ::   Planning   ::   Exercises

Location of Control Lines

Fireline : That part of a control line that is scraped or dug to mineral soil.

Fireline
Fireline in timber

The first planning segment we will discuss is the location of control lines. First of all, we should clarify some commonly used terminology. Although firelines and control lines are frequently used interchangeably, they have a slightly different meaning. Fireline is defined as the part of a control line that is scraped or dug to mineral soil. Firelines are constructed by hand tools or mechanical means. Control lines usually include firelines but also can consist of artificial and natural barriers, retardant lines, and noncombustible fuels.

Location of control lines are usually dependent on:

  1. Accessibility and safety for control forces.
  2. Resource values at risk from the fire and from control actions.
  3. General shape of terrain and available barriers.
  4. Current weather and weather forecasts.
  5. Fuel characteristics over time and space.
  6. Direct or indirect attack methods used.

Flanking a Fire

more

Flanking a fire which is driven by strong winds or is running up slope is common practice because:

  1. The rate of spread on flanks is less.
  2. Forces can work closer due to less heat.
  3. It’s easier to anchor lines and plan escape routes.
  4. Narrower firelines are required to stop spread.
  5. Flanks may be the only safe areas to work direct attack.

Ridgetops

Ridgetops are often selected to locate and construct firelines because:

  1. Access and mobility are usually better for both ground and air attack.
  2. A pause in fire spread usually will result from converging daytime slope winds.
  3. The hazard from rolling embers and rocks is less.
  4. Fuels availability often changes with terrain changes.
  5. Ridgetop winds can be more favorable for burning out or backfiring.

Ridgetop

The figure above illustrates a control line placed a short distance down the back side of a ridge. This, too, is common practice. Why is it better than placing the line on the highest point of a ridge?

Considerations For Steep, Narrow Terrain

Considerations when building control lines in deep, narrow canyons are:

  1. Radiated heat can preheat and dry fuels.
  2. Spotting can occur across a canyon.
  3. There are usually heavier concentrations of fuels present.
  4. Access and escape routes usually are more difficult.
  5. Visibility often is more limited by smoke and heavy fuels.
  6. Use of heavy equipment and air attack can be limited.

Canyon fire

This graphic illustrates a fire burning on the lower slope of a canyon. Near the bottom, the slope is very steep and is a hazardous place to build fireline. The illustration suggests placing the line on the other side, but a short distance up from the bottom. This would certainly be safer and more secure from rolling firebrands, falling snags, and spotting and radiated heat across the canyon.

How about fireline around the rest of the fire? Well, flanking the fire seems reasonable if safety zones can be established. What about working the head? This can be extremely hazardous if the flanks are not yet secure, and safety zones are not readily available.

Copyright 2008, by the Contributing Authors. Cite/attribute Resource . admin. (2005, November 11). Unit 10: Fire Behavior Affects Fireline Tactics. Retrieved January 07, 2011, from Free Online Course Materials — USU OpenCourseWare Web site: http://ocw.usu.edu/Forest__Range__and_Wildlife_Sciences/Wildland_Fire_Management_and_Planning/Unit_10__Fire_Behavior_Affects_Fireline_Tactics_3.html. This work is licensed under a Creative Commons License Creative Commons License