Glossary of Wildfire Terms

S-130/S-190: The basic wildland fire training course given to all U.S. firefighters before they can work on the fire lines.
Safety zone: An area cleared of flammable material used for escape in the event the line is outflanked or in case a spot fire causes fuels outside the control line to render the line unsafe. In firing operations, crews progress so as to maintain a safety zone close at hand allowing the fuels inside the control line to be consumed before going ahead. Safety zones may also be constructed as integral parts of fuel breaks; they are greatly enlarged areas which can be used with relative safety by firefighters and their equipment in the event of blowup in the vicinity.
Sawyer: Chainsaw crew, may also include faller or feller who is qualified to cut down trees or snags, perhaps while the tree or snag is burning.
Secondary line: Any fireline constructed at a distance from the fire perimeter concurrently with or after a line already constructed on or near to the perimeter of the fire. Generally constructed as an insurance measure in case the fire escapes control by the primary line.
SEAT: Single Engine Airtanker - small agricultural aircraft converted for use on fires, predominantly during the initial attack phase.
Size-up: Initial assessment of fire including (among other things) fuel load, fire weather, topography, fire behavior, hazards and exposures of valuable properties. Quickly detects need for additional resources and sets operational priorities.
Skidder unit: Pre-configured tank, pump, hose for attachment to a logging skidder (large 4-wheel-drive tractor with a dozer blade, winch or grapple) to be carried to a fireline.
Slash: Debris resulting from such natural events as wind, fire, or snow breakage; or such human activities as road construction, logging, pruning, thinning, or brush cutting. It includes logs, chunks, bark, branches, stumps, and broken under-story trees or brush. See also logging slash.
Sling load: Cargo net containing supplies or equipment delivered by longline below a helicopter.
Slopover: Fire spreading outside the boundaries of a control line.
Slug: Humorous pejorative term for those believed to be doing less work than you. "Heli-slug" for helislack, "camp slug" for fire camp support personnel, "engine slug" for engine crew member, etc. If you're not a Hotshot or smokejumper you're most likely a slug.
Slurry bomber: See #Airtanker.
Smokechaser: Colloquial term for a wildland firefighter. Now mostly archaic, except in Minnesota where state Department of Natural Resources firefighters are officially known by that name.
Smokejumper: A specifically trained and certified firefighter who travels to remote wildfires by fixed-wing aircraft and parachutes into a jump spot - that may include trees - close to the fire.
Smoldering: A fire burning without flame and barely spreading.
Snag: A dead standing tree that can be hazardous.
Spike camp: Remote camp usually near a fireline, and lacking the logistical support that a larger fire camp would have.
Spotting: Behavior of a fire producing sparks or embers that are carried by the wind and which start new fires (spot fires) beyond the zone of direct ignition by the main fire. A cascade of spot fires can cause a blowup.
Strike team: Specified combinations of the same kind and type of resources, with communications, and a leader.
Suppression: All the work of extinguishing or confining a fire beginning with its discovery.
Suppression crew (also "Soup Crew"): Two or more firefighters stationed at a strategic location for initial action on fires. Duties are essentially the same as those of individual firefighters; often organized into 20-person crews, including supervisors, for simplified logistics and operations.
Surface fire: Fire that burns loose debris on the surface, which include dead branches, blowdown timber, leaves, and low vegetation, as contrasted with crown fire.