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Strategy
English (Text Version) > Fighting Fires > Strategy
Like hurricanes and tornadoes, wildfires are one of the most powerful natural forces--they can strike anywhere without much warning and destroy whatever is in their path. Unlike hurricanes and tornados, it is possible to fight wildfires, though the options are limited.
Houses in danger can be gel wrapped, but this only protects the house; it doesn't do anything to extinguish the wildfire. Water and retardant dumps are also used to fight wildfires, but only work on small wildfires.
There is only one strategy that humans can use to actually stop a wildfire: fire lines. A fire line is an area clear of fuel in the path of a wildfire, or in a position to cut off a route that a wildfire could take. Well-built fire lines are very effective in stopping wildfires because they deprive fires of the fuel necessary for burning.
Making well-built fire lines is easier said than done. It is very important to make fire lines solid, or without any gaps that a wildfire could sneak through. A fire line is usually built up hill from an anchor point to the fire to keep the wildfire from going around it. Initially anchoring the line to a road or other natural barrier further reduces the danger of the wildfire flanking the line. Fire lines are most effective when they are short and without any sharp angles.
A general rule is used by firefighters in determining the width of a fire line: the fire line should be 1.5 times the height of the tallest fuel. This means that to stop a fire in foot-high (30 cm) grass, a fire line should be 1.5 feet (46 cm) wide. To stop a fire burning in trees 80 feet (24 m) tall, a fire line should be 120 feet (37 m) wide. However, firefighters also consider the slope, fuel, weather, and the intensity and size of the fire when deciding on fire line width.
There are two basic methods to attacking a wildfire with fire lines: Direct attack and indirect attack.
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The direct attack method is most often used on wildfires that are mild enough to allow firefighters to build a fire line directly along the edge of the wildfire. This method is typically used on moderate running grass or brush fires, small wildfires, underground fires, and the flank and rear of large wildfires.
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If a fire is small enough, it is possible for firefighters to use the direct attack method and also flank the fire with another fire line. The crew on the fire typically splits into two groups working forward around the flanks and moving toward the head of the fire. The area between the line and the fire is usually burned to remove fuel, regulate heat, and minimize the possibility of crowning.
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When a wildfire is too large, dangerous, or fast moving, or there are not enough firefighters to use the direct attack method, the indirect attack method is utilized. Firefighters build a fire line from behind the wildfire, starting at an anchor point (like a river or road), toward the head of the fire. The line is not built as close to the wildfire as in the direct attack method. Instead, the line is built a safe distance away from the fire, and the area between the fire and the fire line is burned to remove fuel.
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