Just what does it mean when you hear “the fire is now contained?” versus “The fire is now controlled?” Here are some common firefighting terms explained.
A fireline (fire break) is a cleared area intended to stop or suppress a wildfire from spreading. It must be dug down to mineral soil, removing all flammable material including leaves, pine needles, duff (the decomposed material underneath them), surface roots, or overhanging branches—anything that might fuel and spread the wildfire.
The width of a fireline depends on the type of fuel. Grass fires may only require a six-foot wide line, but in a forest with trees towering 60 feet or more, the fire line might require clearance of hundreds or thousands of feet, including full grown trees. Fire crews usually hand dig narrower lines, but in the case of very wide firelines, bulldozers are called in, provided the terrain is not too steep.
Winds also plays an important factor. It is not uncommon for winds to send sparks miles ahead of an advancing fire, setting new fires ahead of the main fire. When this happens, firefighters are in danger of being trapped in between the two.
is fighting fire with fire. There are instances where fires are too large or
too out of control either because of high winds or inaccessible terrain to rely
on hand crews or heavy equipment. Backfiring is a dangerous procedure in which
fire crews set intentionally ignite vegetation in front of the advancing
main fire. Without new fuel to burn, the hope is the fire with starve itself out.
You may have heard fire officials declare either a percent of containment, or that a wildfire is contained. All containment means is that fire crews have completed a fireline around the fire’s perimeter. While it means there’s less risk of the fire raging out of control again, officials at this point are fairly confident that it will not. There’s much work to be done before the fire is officially “controlled."
A fire is consider controlled when it is OUT. And “out” means that fire crews have either mopped-up the entire fire or at least enough of the perimeter extending into the burned area that it is unlikely the fire will resume. What is mopping-up? A dirty, thankless job where firefighters comb the burn area and extinguish every single hotspot, including smoldering stumps, and downed trees.
A prescribed burn is a planned fire to reduce the build-up of fuels and reduce wildfire danger. It’s interesting to note that back in the 1970s when I worked for the Forest Service, fire officials called these “Controlled Burns.” My take on the name change is because fire has proven to never really be completely under human control, the term was dropped and the prescribed burn designation took its place.