The process of completely surrounding a fire with a control line. In a way, the control line contains a wildfire the way a fence corrals or contains livestock. The fire is still actively burning inside this new boundary but is less likely to spread beyond it.


In a sense, "control" of a fire is a step beyond "containment." In addition to completing a control line around a fire, the control line itself must be strengthened and secured to ensure that the fire cannot escape. It's like building a higher fence for that corral. Unburned areas inside the line will be ignited to eliminate nearby fuel, effectively widening the line. Hot spots where smoldering branches or brush or other fuels could potentially flare up have to be put down. The fire is "controlled" when it's unlikely to escape the line.

Hand Crew:

 Any of a number of firefighters that use hand tools, chainsaws, portable pumps, and ignition devices to assist during wildfire operations. This group includes Hotshots.


 A type of hand crew containing from 18 to 25 firefighters that have received intensive training. These firefighters are used primarily for building control lines with hand tools, but unlike other crews, they have as a rule more experience and training and they work as a unit 40 hours a week.

Control Line:

 A barrier that blocks the spread of a fire. It can include natural breaks in the fuel source, such as rivers, lakes or roads. A manmade control line is a strip of ground that has been dug up, burned out or otherwise cleared of fuel ahead of a fire's advance. The width required to prevent flames or embers from crossing and igniting fuels on the other side depends on a number of variables, including wind and weather, the height of the flames, and the lay of the land — a fire burning uphill will travel faster and be more intense, requiring a wider control line to prevent it from escaping.


 The manmade portion of a control line, this is a strip of land that has been dug or scraped down to the layers of soil below the surface that have little combustible material and are unlikely to burn. Fireline is built by hand crews to help complete a control line and contain a fire. The larger the flames and the worse the conditions, the wider the fireline will have to be to contain the oncoming wildfire.

Mopping Up:

Even after a fire is contained and controlled, there will be areas inside the control line with active flames or smoldering materials. "Mopup" involves a number of different tasks aimed at putting out the fire and eliminating fuels that could reignite. This includes knocking down flames with dirt or water, separating and securing large fuels like fallen tree trunks and branches that could tumble over the fireline, and digging out and extinguishing still-burning fuels like roots, peat and pine needles.

Spot fire:

 A fire that starts outside the area of the main fire or beyond the control line. Spot fires can ignite when firebrands (any fire-starting heat sources, such as embers or burning branches) are blown, carried or fall into unburned fuel. Spot fires that ignite more than 600 feet away from the main fire can serve as an indicator of extreme fire behavior.


 A fire intentionally set inside the fireline. The fireline keeps the backfire contained on one side so that it will burn toward the main fire. The objective may be to consume fuel in the path of the oncoming wildfire. It can also be to slow the fire's spread or to change the direction or force of the column of hot gas and smoke rising from the flames (called a convection column). "Backfiring" is a form of indirect attack.


An increase in the rate of spread or the intensity of a fire, but not enough to change the control plan.


 Worse than a flareup, this is an increase in the rate of spread or the intensity of a fire that is bad enough to force a change in the control plan. 


 A section of land that has been stripped bare of vegetation or other fuels in advance in order to stop or slow the spread of a fire. Examples include fire roads in the forest and ornamental rock beds around a home.


A section of land in which shrubs, trees or other fuels have been thinned or trimmed back. Unlike a firebreak, a fuelbreak still contains fuels that can burn, but the thinning process will help to slow the spread of any oncoming fire and will make the area more accessible to firefighters. A fuelbreak will look open and park-like, as opposed to a firebreak, which is cleared to the ground.

Direct attack:

A strategy in which firefighters work very close to the fire's edge, either building fireline or attempting to douse the flames directly with water or dirt. Direct attack can generally only be made if the flames are less than 4 feet long. Though it may sound risky, direct attack can actually be safer for firefighting personnel than indirect attack, since it means they can more easily escape to areas that have already burned — a strategy known as "keeping one foot in the black."

Indirect attack:

A strategy in which firefighters build fireline far away from the fire's edge in preparation for its advance. Backfires are set to burn out fuels ahead of the main fire, and fireline can be combined with existing natural barriers to strengthen the overall control line. Indirect attack is used on very intense or fast-moving fires when direct attack is impossible.

Fire retardant:

A substance other than water that reacts with fuels to make them less flammable, slowing or stopping the progress of a fire. Many people in California will be familiar with the bright orange liquid being dropped from air tankers flying above a wildfire. This "orange slime" is colored to make it easier to see and primarily contains ammonium phosphate, which effectively scorches the outside of a tree when heated, robbing the fire of burnable fuel. The tree remains alive on the inside. (