Glossary of 

Wildland Fire 

Terminology
 

PMS 205 October 2014 

 

 

 

 

 

Glossary of Wildland Fire 

Terminology 

PMS 205 

October 2014 

The National Wildfire Coordinating Group (NWCG) has approved this information for the guidance of 

its groups and member agencies and is not responsible for the interpretation or use of this information by 

anyone except its groups and member agencies. 

Sponsored for NWCG publication by the Data Standards and Terminology Subcommittee. 

Previous editions: 2012, 2011, 2008, 2007, 2006, 2005. 

This publication is published electronically by NWCG on the NWCG Web site at 

http://www.nwcg.gov/pms/pms.htm 

Comments regarding the content of this document should be directed to 

BLM_FA_NWCG_Webmaster@blm.gov 

NWCG information is in the public domain. Use of the information, including copying, is permitted. 

Use of NWCG information within another document is permitted, if NWCG information is accurately 

cited to the NWCG. The NWCG logo may not be used except on NWCG authorized information. 

“National Wildfire Coordinating Group”, “NWCG”, and the NWCG logo are trademarks of the 

National Wildfire Coordinating Group. 

The use of trade, firm, or corporation names in this publication is for the information and convenience of 

the reader and does not constitute an endorsement by the National Wildfire Coordinating Group of any 

product or service to the exclusion of others that may be suitable. 

Preface
 

The Glossary of Wildland Fire Terminology provides an extensive listing of terms and 

definitions used by the National Wildfire Coordinating Group (NWCG) community. 

This document contains terms commonly used by NWCG in the areas of wildland fire 

and incident management and is not intended to list all terms used by NWCG members 

and users. 

The NWCG has approved this glossary for use by the NWCG and its subgroups. The 

NWCG has directed that all NWCG glossaries will be based upon the Glossary of 

Wildland Fire Terminology for the purpose of maintaining definition consistency and 

clarity among documents. 

October 2014 Page 5 

Contents
 

Preface 5
 

Introduction 9
 

Reference Definitions 11
 

Acronyms 13
 

Glossary of terms 21
 

October 2014 Page 7
 

Introduction
 

Scope of the Glossary 

This glossary provides the wildland fire and incident management communities a single 

source document that covers wildland fire, prescribed fire, fire use and incident 

management terminology commonly used by the National Wildfire Coordinating Group 

(NWCG) and its subgroups. 

Objective of the Glossary 

This glossary will help to improve communication and provide consistency in 

terminology usage throughout those organizations with a mission of wildland fire or fire 

use management. It will also facilitate consistent use of glossary terms in publications, 

course development, and incident management activities. 

Maintenance of the Glossary 

This glossary is intended to be a dynamic document, updated on a regular cycle. Those 

wishing to submit terminology for glossary inclusion or to recommend updating or 

removing existing glossary definitions may do so by sending a glossary entry change 

request to: 

NWCG Program Management Unit
 

National Interagency Fire Center
 

3833 S. Development Avenue
 

Boise, ID 83705
 

or by e-mailing the request to: BLM_FA_NWCG_Webmaster@blm.gov 

When submitting a glossary change request, it is requested that the NWCG Entry 

Change Request format be used. An electronic copy of this format can be found with 

the glossary on the NWCG Web site at http://www.nwcg.gov. 

Publication of the Glossary 

For those who wish to access the most up-to-date, interactive version of this glossary, it 

is available via the Internet at the NWCG Web site (http://www.nwcg.gov). An 

electronic version (in PDF format) of the glossary document is also available for 

download or on CD. Instructions for downloading or requesting the CD can be found on 

the Web site. 

October 2014 Page 9 

Reference Definitions
 

Some of the terms within this glossary will be followed by initials or will have 

references or comments at the end of the definition to help broaden the recognition and 

understanding of the term. An explanation of those references is as follows: 

Also called: means there is another term that may sometimes be in use, but is 

not defined in this glossary.
 

Acronym:	 A name made up of the initial letters of a multi-word term or 

official title. An acronym appears in parentheses following the
 

term.
 

See:	 means there is another, preferred term that should be used 

instead. In such a case only the preferred term is defined in this 

glossary.
 

See Also:	 means there are one or more related terms that may also be of 

interest to the glossary user. The related terms are also defined in 

this glossary.
 

Synonym:	 means the term is synonymous with another. The terms have the
 

same, or essentially the same, definition and the terms are
 

interchangeable in their use.
 

October 2014	 Page 11 

Glossary of Wildland Fire Terminology 

Acronyms 

1,000-h TL see: One-thousand Hour Timelag Fuel Moisture 

FM 

100-h TL see: One-hundred Hour Timelag Fuel Moisture 

FM 

10-h TL FM	 see: Ten-hour Timelag Fuel Moisture 

1-h TL FM	 see: One-hour Timelag Fuel Moisture 

AAR	 see: After Action Review 

ABRO	 see: Aircraft Base Radio Operator 

ACAC	 see: Area Command Aviation Coordinator 

ACDR	 see: Area Commander 

ACLC	 see: Assistant Area Commander, Logistics 

ACPC	 see: Assistant Area Commander, Plans 

AD	 see: Administratively Determined 

ADF	 see: Automatic Direction Finder 

ADO	 see: Assistant Disbursing Officer 

AGL	 see: Above Ground Level 

AID	 see: Aerial Ignition Device 

AirNet	 see: Aircraft Network 

ALS	 see: Advanced Life Support 

AMR	 see: Appropriate Management Response 

AMRS	 see: All Hazards Meteorological Response System 

AOBD	 see: Air Operations Branch Director 

AOP	 see: Annual Operating Plan (for Fire Weather) 

APT	 see: Administrative Payment Team 

AREP	 see: Agency Representative 

ASA	 see: Air Stagnation Advisory 

ASGS	 see: Air Support Group Supervisor 

ATA	 see: Actual Time of Arrival 

ATCO	 see: Air Tanker/Fixed-Wing Coordinator 

ATD	 see: Actual Time of Departure 

ATE	 see: Actual Time En Route 

ATGS	 see: Air Tactical Group Supervisor 

ATIM	 see: Aircraft Timekeeper 

ATV	 see: All Terrain Vehicle 

AWS	 see: Automatic Weather Station 

BACM	 see: Best Available Control Measures 

BCMG	 see: Base Manager 

see: Camp Manager 

BLEVE	 see: Boiling Liquid Expanding Vapor Explosion 

BLS	 see: Basic Life Support 

Btu	 see: British Thermal Unit 

BUI	 see: Buildup Index 

CAFS	 see: Compressed Air Foam Systems 

October 2014	 Page 13 
Glossary of Wildland Fire Terminology 

CFP	 see: Cooperative Fire Protection 

CISD	 see: Critical Incident Stress Debriefing 

CLMS	 see: Claims Specialist 

CMSY	 see: Commissary Manager 

CO	 see: Carbon Monoxide 

CO2	 see: Carbon Dioxide 

COML	 see: Communications Unit Leader 

COMP	 see: Compensation/Claims Unit Leader 

COMT	 see: Incident Communications Technician 

COST	 see: Cost Unit Leader 

CRWB	 see: Crew Boss 

CWPP	 see: Community Wildfire Protection Plan 

DA	 see: Departure from Average Greenness 

DAID	 see: Delayed Aerial Ignition Devices 

DDP	 see: Designated Dispatch Point 

DE	 see: Dry Episode 

DECK	 see: Deck Coordinator 

DISE	 see: Distributed Incident Simulation Exercise 

DIVS	 see: Division/Group Supervisor 

DL	 see: Distance Learning 

see: Fuel Dryness Level 

DME	 see: Distance Measuring Equipment 

DMOB	 see: Demobilization Unit Leader 

DOB	 see: Depth of Burn 

DOCL	 see: Documentation Unit Leader 

DOZB	 see: Dozer Boss 

DPRO	 see: Display Processor 

DZ	 see: Drop Zone 

EFF	 see: Emergency Firefighter 

EFp	 see: Emission Factor 

EFSA	 see: Escaped Fire Situation Analysis 

ELT	 see: Emergency Locator Transmitter 

EMC	 see: Equilibrium Moisture Content 

EMTB	 see: Emergency Medical Technician - Basic 

EMTI	 see: Emergency Medical Technician - Intermediate 

EMTP	 see: Emergency Medical Technician - Paramedic 

EOC	 see: Emergency Operations Center 

ERC	 see: Energy Release Component 

ETA	 see: Estimated Time of Arrival 

ETD	 see: Estimated Time of Departure 

ETE	 see: Estimated Time En Route 

FAC	 see: Fire Adapted Community 

FACL	 see: Facilities Unit Leader 

FAR	 see: Federal Aviation Regulation 

FDUL	 see: Food Unit Leader 

October 2014	 Page 14 
Glossary of Wildland Fire Terminology 

FIRES see: Fire Information Retrieval and Evaluation System
 

FIRETIP see: Firefighting Technology Implementation Program
 

FLE see: Fireline Explosives 

FLI see: Fire Load Index 

FLIR see: Forward Looking Infrared 

FLPMA see: Federal Land Policy and Management Act 

FMP see: Fire Management Plan 

FMU see: Fire Management Unit 

FOBS see: Field Observer 

FOFE see: First Order Fire Effects 

FORPLAN see: Forest Planning Language and Simulator 

FPU see: Fire Planning Unit 

FRA see: Friction Reducing Agent 

FSC1 or see: Finance/Administration Section Chief 

FSC2 

FWI see: Fire Weather Index 

FWIS see: Forestry Weather Information System 

GACC see: Geographic Area Coordination Center 

GACG see: Geographic Area Coordinating Group 

GAWR see: Gross Axle Weight Rating 

GISS see: Geographic Information System Specialist 

GOES see: Geostationary Operational Environmental Satellite 

GPM see: Gallons per Minute 

GPS see: Global Positioning System 

GSA see: General Services Administration 

GSUL see: Ground Support Unit Leader 

GTS see: Gum Thickened Sulphate 

GVW see: Gross Vehicle Weight 

GVWR see: Gross Vehicle Weight Rating 

HCWN see: Helicopter Manager 

HEB1 or see: Helibase Manager 

HEB2 

HECM see: Helicopter Crewmember 

HELB see: Helicopter Boss 

HERO see: Helibase Radio Operator 

HESM see: Helispot Manager 

HIGE see: Hovering in Ground Effect 

HLCO see: Helicopter Coordinator 

HRSP see: Human Resource Specialist 

IA see: Initial Attack 

IAF see: Initial Attack Fire 

IAIC see: Initial Attack Incident Commander 

IAP see: Incident Action Plan 

IARR see: Interagency Resources Representative 

IAS see: Indicated Airspeed 

IBA see: Incident Business Advisor 

October 2014 Page 15 
Glossary of Wildland Fire Terminology 

ICP see: Incident Command Post 

ICS see: Incident Command System 

ICT1, ICT2, see: Incident Commander 

ICT3, ICT4, 

or ICT5 

ID	 see: Inside Diameter 

IFPL	 see: Industrial Fire Precaution Level 

IFR	 see: Instrument Flight Rules Conditions 

ILS	 see: Instrument Landing System 

IMET	 see: Incident Meteorologist 

IMI	 see: Interactive Multimedia Instruction 

IMSA	 see: Incident Medical Specialist Assistant 

IMSM	 see: Incident Medical Specialist Manager 

IMST	 see: Incident Medical Specialist Technician 

INCM	 see: Incident Communications Manager 

INVF	 see: Wildland Fire Investigator 

IPT	 see: Iron Pipe Thread 

IR	 see: Infrared 

see: Infrared Groundlink 

JIC	 see: Joint Information Center 

JIS	 see: Joint Information System 

KBDI	 see: Keetch-Byram Drought Index 

L/RMP	 see: Land/Resource Management Plan 

LAL	 see: Lightning Activity Level 

LC	 see: Liquid Concentrate 

LCES	 see: Lookout(s), Communication(s), Escape Route(s), and Safety Zone(s) 

LCMS	 see: Learning Content Management System 

LOFR	 see: Liaison Officer 

LR	 see: Lightning Risk 

LSC1 or see: Logistics Section Chief 

LSC2 

MAC see: Multi-Agency Coordination 

MAC Group see: Multi-Agency Coordinating Group 

MACS see: Multi-Agency Coordination System 

MAFFS see: Modular Airborne Firefighting System 

MEDL see: Medical Unit Leader 

MEL see: Most Efficient Level 

Micro- see: Micro-Remote Environmental Monitoring System 

REMS 

MIST	 see: Minimum Impact Suppression Techniques 

MMA	 see: Maximum Manageable Area 

see: Maximum Management Area 

MOA	 see: Military Operations Area 

MSL	 see: Mean Sea Level 

NAAQS	 see: National Ambient Air Quality Standards 

NARTC	 see: National Advanced Resources Technology Center 

October 2014	 Page 16 
Glossary of Wildland Fire Terminology 

NASF	 see: National Association of State Foresters 

NDVI	 see: Normalized Difference Vegetation Index 

NESDIS	 see: National Environmental Satellite, Data and Information Service 

NFC	 see: National Fire Codes 

NFDRS	 see: National Fire Danger Rating System 

NFPA	 see: National Fire Protection Association 

see: National Fire Protection Association Standards 

NH	 see: National Standard Thread 

NICC	 see: National Interagency Coordination Center 

NIFC	 see: National Interagency Fire Center 

NIFMID	 see: National Interagency Fire Management Integrated Database 

NIIMS	 see: National Interagency Incident Management System 

NO	 see: Nitrogen Oxide 

NO2	 see: Nitrogen Dioxide 

NOTAM	 see: Notice to Airmen 

NPSH	 see: National Pipe Straight Hose Thread 

NRL	 see: National Resource Lands 

NVC	 see: Net Value Change 

NWCG	 see: National Wildfire Coordinating Group 

OCC	 see: Operations Coordination Center 

OD	 see: Outside Diameter 

OI	 see: Occurrence Index 

OPBD	 see: Operations Branch Director 

ORDM	 see: Ordering Manager 

ORV	 see: Off-road Vehicle 

OSC1 or	 see: Operations Section Chief 

OSC2 

PAL see: Project Activity Level 

PAR see: Precision Approach Radar 

PIBAL see: Pilot Balloon Operation 

PIO1, PIO2, see: Public Information Officer 

PIOF 

PM10 see: PM10 

PM2.5 see: PM2.5 

PPE see: Personal Protective Equipment 

PROC see: Procurement Unit Leader 

PSC1 or see: Planning Section Chief 

PSC2 

PSD	 see: Plastic Sphere Dispenser 

see: Prevention of Significant Deterioration 

PSI	 see: Pounds per Square Inch 

PTB	 see: Position Task Book 

RACM	 see: Reasonably Available Control Measures 

RAWS	 see: Remote Automatic Weather Station 

RCDM	 see: Receiving and Distribution Manager 

RECON	 see: Reconnaissance 

October 2014	 Page 17 
Glossary of Wildland Fire Terminology 

RESL see: Resources Unit Leader 

RFD see: Rural Fire District 

RG see: Relative Greenness 

RH see: Relative Humidity 

RM see: Risk Management 

ROSS see: Resource Ordering and Status System 

SA see: Situation Awareness 

see: Situational Awareness 

SAFENET see: SAFENET 

SAIT see: Serious Accident Investigation Team 

SCBA see: Self-Contained Breathing Apparatus 

SCKN see: Status/Check-In Recorder 

SCO see: Shareable Content Object 

SCORM see: Shareable Content Object Re-usable Model 

SECM see: Security Manager 

SHEF see: Standard Hydrologic Exchange Format code 

SIG see: Special Interest Group 

SIMWYE see: Reversible Siamese 

SIP see: State Implementation Plan 

SITL see: Situation Unit Leader 

SOFE see: Second Order Fire Effects 

SOP see: Standard Operating Procedure 

see: Standard Operational Procedure 

SPUL see: Supply Unit Leader 

SSA see: Smoke-Sensitive Area 

STAM see: Staging Area Manager 

STCR see: Strike Team leader Crew 

STCR, see: Strike Team Leader 

STDZ, 

STEN or 

STPL 

STDZ see: Strike Team Leader Dozer 

STEN see: Strike Team Leader Engine 

STEX see: Sand Table Exercise 

STPL see: Strike Team Leader Tractor/Plow 

STPS see: Structure Protection Specialist 

SUBD see: Support Branch Director 

SVBD see: Service Branch Director 

TDGS see: Tactical Decision Game 

TFLD see: Task Force Leader 

TFR see: Temporary Flight Restriction 

THSP see: Technical Specialist 

TIME see: Time Unit Leader 

TL see: Timelag 

TNSP see: Training Specialist 

TOLC see: Take-off and Landing Coordinator 

October 2014 Page 18 
Glossary of Wildland Fire Terminology 

TSP see: Total Suspended Particulate Matter 

UHF-FM see: Ultra High Frequency 

VFD see: Volunteer Fire Department 

VFR see: Visual Flight Rules Conditions 

VG see: Visual Greenness 

VHF-AM see: Very High Frequency 

VOR see: VHF Omnidirectional Radio Range 

VRM see: Visual Resource Management 

WCT see: Work Capacity Test 

WEPS see: Water Expansion Pumping System 

WES see: Water Expansion System 

WFAS see: Wildland Fire Assessment System 

WFMI see: Wildland Fire Management Information 

WIMS see: Weather Information Management System 

WRCC see: Western Regional Climate Center 

WUI see: Wildland Urban Interface 

October 2014 Page 19 
Glossary of Wildland Fire Terminology 

October 2014 Page 20
 
 

 

 

 

Glossary of Wildland Fire Terminology 

- 6 -

6 Minutes for Safety 

1	 A daily safety briefing for wildland fire that focuses on high risk events found within a firefighter's 

scope of work that are performed on an infrequent basis. 

- A -

Abort 

1	 To jettison a load of water or retardant from an aircraft, or terminate a preplanned aircraft 

maneuver. 

Abort Area 

1	 A designated area where unused quantities of water or fire retardant may be jettisoned, usually 

to permit an air tanker to land with less than a full load. 

Above Ground Level (AGL) 

1	 Term frequently used in aviation operations, usually in connection with a stated altitude. 

Absolute Humidity 

1	 Total amount of water vapor in the air. 

Absorption 

1 Act of soaking up and retaining a gas in liquid or in a solid; also retention of radiant energy. 

Accelerant 

1	 Material ( usually a flammable liquid) used to initiate or increase the spread of a fire. 

Acceptable Fire Risk 

1	 The potential fire loss a community is willing to accept rather than provide resources to reduce 

such losses. 

Accessibility Burn 

1	 The burning of understory prior to the sale of forest products to improve the efficiency of timber 

marking and harvesting. 

Action Plan 

1 Any tactical plan developed by any element of ICS in support of the incident action plan.
 

see also: Incident Action Plan
 

Active Crown Fire 

1	 A fire in which a solid flame develops in the crowns of trees, but the surface and crown phases 

advance as a linked unit dependent on each other. 

Active Resources 

1	 Resources checked in and assigned work tasks on an incident. 

synonym: Assigned Resources
 

see also: Allocated Resources
 

Available Resources
 

October 2014	 Page 21 
 

 

 

Glossary of Wildland Fire Terminology 

Activity Fuels 

1 Fuels resulting from, or altered by, forestry practices such as timber harvest or thinning, as 

opposed to naturally created fuels. 

see also: Logging Debris 

Natural Fuels 

Actual Time En Route (ATE) 

1 Term used in flight planning/following to document actual time spent flying between points. 

Actual Time of Arrival (ATA) 

1	 Term used in flight planning/following to document time of arrival at a point. 

Actual Time of Departure (ATD) 

1	 Term used in flight planning/following to document time of departure from a point. 

Adapter 

1 A device for connecting hoses of the same size with non-matching hose threads, or connecting 

a threaded coupling to a quick-connect coupling. 

see also: Coupling 

Adiabatic Process 

1	 Thermodynamic change of state in which no heat is added or subtracted from a system; 

compression always results in warming, expansion in cooling. 

Adjective Rating 

1	 A public information description of the relative severity of the current fire danger situation. 

Administrative Payment Team (APT) 

1	 A team that supports incident agencies by processing payments for resources. Resources may 

include emergency equipment, casuals, local vendors for supplies, etc. 

Administratively Determined (AD) 

1 A person hired and compensated under the Pay Plan for Emergency Workers. 

synonym: Casual
 

see also: Emergency Firefighter
 

Admission 

1	 Oral or written statement tending to link its maker to involvement in a particular crime. 

Advanced Life Support (ALS) 

1	 Advanced life support skills performed by an EMS practitioner or service, e.g. intravenous fluids 

and drug administration. 

Advancing a Line 

1	 Moving a hose lay toward a specified area from the point where the hose-carrying apparatus 

has stopped. 

Advancing Fire 

1 That portion of the fire with rapid fire spread with higher intensity which is normally burning with 

the wind and/or up slope. Also called: forward fire, or a run. 

synonym: Head Fire 

Advancing Front Combustion Stage 

1	 The period of combustion when a fire is spreading, usually accompanied by flaming combustion 

that releases heat to sustain the convection column. 

October 2014	 Page 22 
 

 

Glossary of Wildland Fire Terminology 

Advection 

1	 The transfer of atmospheric properties by the horizontal movement of air, usually in reference to 

the transfer of warmer or cooler air, but may also refer to moisture. 

Adze Hoe 

1	 A fire-trenching or digging tool having a sharp, tempered blade, which is useful for heavy 

grubbing, trenching, and light cutting.
 

Aerial Detection 

1	 A system for, or the act of discovering, locating, and reporting fires from aircraft. 

Aerial Fuels 

1 Standing and supported live and dead combustibles not in direct contact with the ground and 

consisting mainly of foliage, twigs, branches, stems, cones, bark, and vines. 

see also: Draped Fuels 

Aerial Ignition 

1	 Ignition of fuels by dropping incendiary devices or materials from aircraft. 

Aerial Ignition Device (AID) 

1	 Inclusive term applied to equipment designed to ignite wildland fuels from an aircraft. 

see also:	 Delayed Aerial Ignition Devices
 

Helitorch
 

Ping-Pong Ball System
 

Plastic Sphere Dispenser
 

Aerial Observer 

1	 A person specifically assigned to discover, locate, and report wildland fires from an aircraft and 

to observe and describe conditions at the fire scene. 

Aerial Photo Interpreter 

1	 A person skilled in identification and measurements of natural and cultural features on aerial 

photographs. 

Aerial Reconnaissance 

1	 Use of aircraft for detecting and observing fire behavior, values-at-risk, suppression activity, and 

other critical factors to facilitate command decisions on strategy and tactics needed for fire 

suppression. 

Aerial Torch 

1	 An ignition device suspended under a helicopter, capable of dispensing ignited fuel to the 

ground for assistance in burning out or backfiring. 

Affidavit 

1	 A statement of declaration in writing and affirmed before an official with authority to administer 

an oath; a statement of declaration alleging fact to support the issuance of a search or arrest 

warrant. 

After Action Review (AAR) 

1	 A structured review or de-brief process of an event, focused on performance standards, that 

enables participants to discover for themselves what happened, why it happened, and how to 

sustain strengths and improve on weaknesses. After action reviews, informal or formal, follow 

the same general format, involve the exchange of ideas and observations, and focus on 

improving performance. 

October 2014	 Page 23 
 

Glossary of Wildland Fire Terminology 

Agency 

1	 An administrative division of a government with a specific function, or a non-governmental 

organization (e.g., private contractor, business, etc.) that offers a particular kind of assistance. A 

federal, tribal, state or local agency that has direct fire management or land management 

responsibilities or that has programs and activies that support fire management activities. 

see also:	 Assisting Agency
 

Cooperating Agency
 

Supporting Agency
 

Agency Administrator 

1	 The official responsible for the management of a geographic unit or functional area. The 

managing officer of an agency, division thereof, or jurisdiction having statutory responsibility for 

incident mitigation and management. Examples: NPS Park Superintendent, BIA Agency 

Superintendent, USFS Forest Supervisor, BLM District Manager, FWS Refuge Manager, State 

Forest Officer, Tribal Chairperson, Fire Chief, Police Chief. 

see also:	 Line Officer 

Agency Certification 

1	 The process whereby the employing agency or contractor documents that the individual is fully 

qualified to perform duties and responsibilities for a specified position. 

Agency Dispatch 

1	 The agency or jurisdictional facility from which resources are allocated to incidents. 

Agency Dispatcher 

1 A person working within an agency organization who processes resources to and from
 

incidents. 

see also: Dispatcher
 

Agency Representative (AREP) 

1	 This ICS position serves as the point of contact for an assisting or cooperating agency which 

has been delegated authority to make decisions on matters affecting that agency's participation 

at the incident and reports to the Liaison Officer. 

see also:	 Assisting Agency
 

Cooperating Agency
 

Agency/Area Coordination Center 

1	 A facility which serves as a central point for one or more agencies to use in processing
 

information and resource requests. It may also serve as a dispatch center for one of the 

agencies. 

Air Ambulance 

1	 A rotary wing aircraft configured, staffed and equipped to respond, care for and transport a 

patient(s) and approved/licensed by a state to do so. An air ambulance is sometimes referred to 

as a medevac. 

Air Attack 

1	 The deployment of fixed-wing or rotary aircraft on a wildland fire, to drop retardant or 

extinguishing agents, shuttle and deploy crews and supplies, or perform aerial reconnaissance 

of the overall fire situation. 

Air Attack Base 

1 Permanent facility at which aircraft are stationed for use in air attack operations. 

see also: Reload Base
 

Air Cargo 

1	 All items for transport and delivery by aircraft. 

October 2014	 Page 24 
Glossary of Wildland Fire Terminology 

Air Contaminant 

1 An airborne dust, fume, gas, mist, odor, smoke, vapor, soot, pollen, carbon, acid or particulate 

matter or any combination thereof. 

see also: Air Pollution 

Air Guard 

1	 A common VHF-FM frequency used by natural resource agency aircraft for emergency radio 

transmissions. Also called national air safety guard frequency. 

Air Mass 

1	 An extensive body of air having the same properties of temperature and moisture in a horizontal 

plane. 

Air Operations Branch Director (AOBD) 

1	 This ICS position is responsible for management of an incident's air operations and reports to 

the Operations Section Chief. 

Air Pack 

1	 Portable air (not oxygen) tanks with regulators which allow firefighters to breathe while in toxic 

smoke conditions. Usually rated for 30 minutes of service. Used primarily on fires involving 

structures or hazardous materials. 

synonym: Self-Contained Breathing Apparatus
 

see also: Respirator
 

Air Pollution 

1	 The general term referring to the undesirable addition of substances (gases, liquids, or solid 

particles) to the atmosphere that are foreign to the natural atmosphere or are present in 

quantities exceeding natural concentrations. 

see also: Air Contaminant 

Air Pollution Alert 

1	 A statement issued by an Air Quality Regulatory Agency due to high measured concentrations 

of pollutants. The alert remains in effect until monitoring shows a decrease in pollutant levels. 

Should conditions worsen, air pollution warnings and emergencies may be issued. At each 

stage (alert, warning and emergency) additional emission restrictions are put into effect so as to 

not intensify the situation. Essentially, at the emergency level all industrial activities and auto 

usage stop. 

Air Quality 

1	 The composition of air with respect to quantities of pollution therein; used most frequently in 

connection with "standards" of maximum acceptable pollutant concentrations. Used instead of 

"air pollution" when referring to programs. 

Air Quality Model 

1	 Mathematical or quantitative representation or simulation of air quality processes; e.g., emission 

models, receptor models, or air quality dispersion models. 

Air Stagnation Advisory (ASA) 

1	 A statement issued by a National Weather Service forecast office when atmospheric conditions 

are stable enough such that the potential exists for air pollutants to accumulate in a given area. 

The statement is initially issued when conditions are expected to last for at least 36 hours. 

Air Support Group Supervisor (ASGS) 

1	 This ICS position is responsible for overseeing logistical support and management of helibase 

and helispot operations and temporary fixed-wing base(s) and reports to the Air Operations 

Branch Director. This position also maintains liaison with air tanker and fixed-wing bases 

supporting incident operations. 

October 2014	 Page 25 
Glossary of Wildland Fire Terminology 

Air Tactical Group Supervisor (ATGS) 

1 This ICS position is responsible for directing and coordinating airborne aircraft operations and 

management of an incident's airspace and reports to the Air Operations Branch Director. 

Air Tanker 

1	 Fixed-wing aircraft certified by FAA as being capable of transport and delivery of fire retardant 

solutions. 

Air Tanker/Fixed-Wing Coordinator (ATCO) 

1	 This ICS position is responsible for coordinating air tanker and fixed-wing operations over an 

incident and reports to the Air Tactical Group Supervisor. 

Aircraft Accident 

1	 An unplanned event that does substantial damage or causes serious injuries when associated 

with the operation of applicable aircraft. Event occurs between the time engine(s) is (are) started 

or rotors turning for the purpose of commencing flight, until the aircraft comes to rest with 

engines and propellers or rotors stopped, the brakes set or wheel chocks in place, and all 

persons have disembarked. 

Aircraft Base Radio Operator (ABRO) 

1	 This ICS position is responsible for maintaining base communications with assigned helicopters, 

helibases, helispots, air operations personnel, and project aviation manager, and reports to the 

Helibase Manager. 

Aircraft Data Card 

1	 Card or documentation required to be on board the aircraft which approves use and indicates 

specific types of use. 

Aircraft Footprint 

1	 That area on the surface of the earth, runway, or ramp that is covered by the tread of the aircraft 

tire while the aircraft is motionless. Also called wheel loading. 

Aircraft Ground Mishap 

1	 An aircraft mishap in which there is no intent to fly. However, the power plants and/or rotors are 

in operation and damage is incurred requiring replacement or repair of rotors, propellers, 

wheels, tires, wing tips, flaps, etc., or injury is incurred requiring first-aid or medical attention. 

Aircraft Incident 

1 An unplanned event that results in damage which is less than serious aircraft incident criteria, or 

injuries not requiring medical attention. 

see also: Serious Aircraft Incident 

Aircraft Network (AirNet) 

1	 Applies to radio frequencies primarily used for air operations. 

Aircraft Timekeeper (ATIM) 

1	 This ICS position is responsible for keeping time and other information concerning helicopters 

assigned to a helibase and reports to the Helibase Manager. 

Alidade 

1 A sighting device used by lookouts to determine the horizontal bearing and sometimes the
 

vertical angle of a fire from a lookout. 

synonym: Osborne Firefinder
 

see also: Firefinder Map
 

October 2014	 Page 26 
 

Glossary of Wildland Fire Terminology 

All Hazard Incident 

1	 An incident, natural or human-caused, that requires an organized response by a public, private, 

and/or governmental entity to protect life, public health and safety, values to be protected, and 

to minimize any disruption of governmental, social, and economic services. One or more kinds 

of incident (fire, flood, mass casualty, search, rescue, evacuation, etc.) may occur 

simultaneously as part of an all hazard incident response. 

see also:	 Incident
 

Values To Be Protected
 

All Hazards Meteorological Response System (AMRS) 

1 A mobile weather data collection and forecasting system consisting of two-way satellite
 

communications and a laptop computer. Used by incident meteorologists on an incident. 

see also: Incident Meteorologist
 

Micro-Remote Environmental Monitoring System
 

All Terrain Vehicle (ATV) 

1 Any motorized vehicle designed for or capable of cross-country travel on or immediately over 

land, water, sand, snow, ice, marsh, swampland, or other terrain. 

synonym: Off-road Vehicle 

Alligatoring 

1 Char patterns formed on paint or burned wood remains, usually in the shape of blisters.
 

see also: Depth of Char Indicators
 

Allocated Resources 

1	 Resources dispatched to an incident, that have not yet checked in. 

see also:	 Active Resources
 

Assigned Resources
 

Available Resources
 

Allowable Payload 

1 The amount of weight that is available for passengers and/or cargo. On the load calculation form 

it is the operating weight subtracted from the selected weight. 

see also: Operating Weight 

Altimeter Setting 

1	 The barometric pressure reading used to adjust a pressure altimeter for variations in existing 

atmospheric pressure or to the standard altimeter setting (29.92) inches. 

Ambient Air 

1	 Air of the surrounding environment. 

Ambulance 

1 A ground transport vehicle configured, equipped and staffed to respond, care for and transport a 

patient(s) and approved by a state to do. 

see also: Air Ambulance 

Anchor Point 

1	 An advantageous location, usually a barrier to fire spread, from which to start constructing a 

fireline. The anchor point is used to minimize the chance of being flanked by the fire while the 

line is being constructed. 

Anemometer 

1	 An instrument designed to measure wind speed. 

October 2014	 Page 27 
 

Glossary of Wildland Fire Terminology 

Angle of Char Indicators 

1	 Standing fuels that are burned at an angle that indicates the direction of fire spread. Also called 

vertical char. 

Annual Certification 

1	 Annual review by an employing agency of an individual's position qualifications and 

documentation certifying that the individual is fully qualified to perform duties and responsibilities 

for a specified position. Annual certification is based on established performance standards and 

agency specific requirements. 

Annual Operating Plan (for Fire Weather) (AOP) 

1	 A procedural guide which describes fire meteorological services provided within the Geographic 

Area of responsibility, including the National Interagency Fire Center. The guide is based on the 

National Interagency Agreement and applicable Geographic Area Memorandum of Agreement. 

Annual Plant 

1	 A plant that lives for one growing season, starting from a seed each year. 

Anticyclone 

1 An area of high atmospheric pressure with closed clockwise circulation.
 

see also: Surface High
 

Apparatus 

1	 A motor-driven vehicle, or group of vehicles, designed and constructed for the purpose of 

fighting fires. May be of different types such as engines, water tenders, ladder trucks, etc. 

Appropriate Management Response (AMR) 

1	 Any specific action suitable to meet fire management objectives. Typically, the AMR ranges 

across a spectrum of tactical options (from monitoring to intensive management actions). The 

response action is based on an evaluation of risks to firefighter and public safety, the 

circumstances under which the fire occurs, including weather and fuel conditions, natural and 

cultural resource management objectives, protection priorities, and values to be protected. The 

evaluation must also include an analysis of the context of the specific fire within the overall local, 

geographic area, or national wildland fire situation. 

see also:	 Fire Management Objective
 

Fire Management Plan
 

Approved 

1	 In fire service terminology, that which is inspected and listed by recognized fire-testing agencies. 

The term as used in National Fire Protection Association standards means approval by the 

authority having jurisdiction, such as the fire chief, insurance inspection department, or other 

agency that enforces standards or regulations. 

Aramid 

1	 The generic name for a high-strength, flame-resistant, synthetic fabric used in the shirts and 

jeans of firefighters. Nomex ®, a brand name for aramid fabric, is the term commonly used by 

firefighters. 

see also:	 Nomex ® 

Area Command 

1 An organization established to: 1) oversee the management of multiple incidents that are each 

being handled by an incident management team (IMT) organization; or 2) to oversee the 

management of a very large incident that has multiple IMTs assigned to it. Area Command has 

the responsibility to set overall strategy and priorities, allocate critical resources based on 

priorities, ensure that incidents are properly managed, and that objectives are met and 

strategies followed. 

October 2014	 Page 28 
 

 

Glossary of Wildland Fire Terminology 

Area Command Aviation Coordinator (ACAC) 

1 The ICS position responsible for ensuring effective use of air resources and supplies among 

those incidents under Area Command management. Reports to the Area Commander. 

see also: Area Command 

Area Commander (ACDR) 

1	 The ICS position responsible for the overall direction of incident management teams assigned to 

the same incident or incidents in close proximity managed under Area Command. Position 

responsibilities include ensuring that conflicts are resolved, compatible incident objectives are 

established, and strategies are selected for the use of critical resources among assigned 

incident management teams. 

see also: Area Command 

Area Ignition 

1	 Ignition of several individual fires throughout an area, either simultaneously or in rapid 

succession, and so spaced that they add to and influence the main body of the fire to produce a 

hot, fast-spreading fire condition. Also called simultaneous ignition. 

Area of Influence 

1	 Delineated area surrounding a base which can be reached first by the ground or air attack units 

assigned to the base. Also called zone of influence. 

Area Source 

1	 A source category of air pollution that generally extends over a large area. Prescribed burning, 

field burning, home heating, and open burning are examples of area sources. 

Armed 

1	 A term used to indicate that the air tanker dropping mechanism is set to allow a programmed 

release of part or all of the load of fire retardant. 

Arrest 

1	 The taking or keeping of a person in custody by legal authority, especially in response to a
 

criminal charge. 

Arson 

1	 At common law, the malicious and willful burning of another’s dwelling, outhouse or parcel; by 

most modern statutes, the intentional and wrongful burning of someone else's, or one's own, 

property. Frequently requires proof of malicious or wrongful intent. 

Arson Fire 

1	 A fire that is intentional and wrongfully set to burn one's own or someone else's property. 

Arson Task Force 

1	 Group of individuals convened to analyze, investigate and solve arson problems in a particular 

region. 

Arsonist 

1	 One who commits arson. 

Ash Indicators 

1	 White ash deposited on the origin side of objects. 

Aspect 

1 Cardinal direction toward which a slope faces. 

see also: Exposure
 

October 2014	 Page 29 
 

Glossary of Wildland Fire Terminology 

Aspirate (Foam) 

1	 To draw in gases (or other substances); nozzle aspirating systems draw air into the nozzle to 

mix with the foam solution. 

Assessment 

1 A fire weather fire danger product based on a thorough evaluation of all pertinent sources of 

meteorological, fire danger and resource information. 

2 The evaluation and interpretation of measurements, intelligence, and other information to 

provide a basis for decision-making. 

Assigned Resources 

1 Resources checked in and assigned work tasks on an incident.
 

synonym: Active Resources
 

see also: Allocated Resources
 

Available Resources
 

Assignments 

1	 Tasks given to resources to perform within a given operational period, based upon tactical
 

objectives in the incident action plan. 

Assistant 

1	 Term used as a title for subordinates of the command staff positions. In some cases, assistants 

are also assigned to unit leader positions in the planning, logistics, and finance/administration 

sections. Qualifications, technical capability, and responsibility of assistants are normally less 

than those of the person holding the primary position. 

Assistant Area Commander, Logistics (ACLC) 

1	 The ICS position responsible for providing facilities, services and materials at the Area 

Command level, and for ensuring effective use of critical resources and supplies among those 

incidents under Area Command management. Reports to the Area Commander. 

see also:	 Area Command 

Assistant Area Commander, Plans (ACPC) 

1	 The ICS position responsible for collecting information from those incidents under Area 

Command management in order to assess, evaluate potential conflicts in establishing incident 

objectives, strategies, and prioritizing use of critical resources. Reports to the Area Commander. 

see also:	 Area Command 

Assistant Disbursing Officer (ADO) 

1	 Person with authority to pay wildland fire suppression crews, transient labor, local residents, and 

vendors with US Treasury checks. 

Assisting Agency 

1 An agency directly contributing tactical or service resources to another agency. 

see also:	 Agency
 

Agency Representative
 

Cooperating Agency
 

Supporting Agency
 

Assumption 

1 Acceptance of information as true without proof or demonstration. 

see also: False Assumption
 

Atmometer 

1	 An instrument that provides an approximate measure of evapotranspiration by measuring the 

water loss from an artificial evaporating surface. 

October 2014	 Page 30 
Glossary of Wildland Fire Terminology 

Atmospheric Inversion 

1	 Departure from the usual increase or decrease with altitude of the value of an atmospheric 

property (in fire management usage, nearly always refers to an increase in temperature with 

increasing height). 

2	 The layer through which this departure occurs (also called inversion layer). The lowest altitude 

at which the departure is found is called the base of the inversion. 

see also:	 Atmospheric Stability
 

Inversion
 

Stable Layer of Air
 

Atmospheric Pressure 

1 The force exerted by the weight of the atmosphere, per unit area. 

see also: Barometric Pressure
 

Atmospheric Stability 

1	 The degree to which vertical motion in the atmosphere is enhanced or suppressed. Vertical 

motions and pollution dispersion are enhanced in an unstable atmosphere. Thunderstorms and 

active fire conditions are common in unstable atmospheric conditions. Stability suppresses 

vertical motion and limits pollution dispersion. 

see also:	 Atmospheric Inversion
 

Inversion
 

Stable Layer of Air
 

Attack a Fire 

1	 Limit the spread of fire by any appropriate means. 

Attack Line 

1	 A line of hose, preconnected to the pump of a fire apparatus and ready for immediate use in 

attacking a fire. Contrasted to supply lines connecting a water supply with a pump or to feeder 

lines extended from a pump to various points around the perimeter of a fire. 

Attack Time 

1	 The starting date, hour, and minute of the first suppression work on a fire. 

Attack Unit 

1	 Single vehicle or aircraft and its associated personnel and material provided for the purpose of 

responding to and abating a fire or other emergency. 

Attack Unit Response 

1	 The response of one attack unit to a fire or other emergency with no regard for the number of 

return trips to that same fire or emergency. 

Attainment Area 

1	 An area considered to have air quality as good as, or better than, the National Ambient Air 

Quality Standards (NAAQS) as defined in the Clean Air Act. An area may be in attainment for 

one or more pollutants but be in nonattainment for one or more other pollutants. 

Automatic Direction Finder (ADF) 

1	 An aircraft radio navigational receiver operating in the low frequency bands. 

Automatic Weather Station (AWS) 

1 A non-GOES telemetered weather station that provides hourly observations to a local 

database. 

see also: Manual Weather Station
 

October 2014	 Page 31 
 

Glossary of Wildland Fire Terminology 

Automatically Regulated 

1	 A proportioning method or device that readily adjusts to changes in water flow and or pressure 

to maintain a desired mix ratio. 

Autorotation 

1	 A helicopter flight condition in which the lifting rotor is driven entirely by action of air when the 

helicopter is in motion. 

Auxiliary Pump 

1	 A secondary pump on an engine in addition to the main pump. Usually of small capacity. 

Available Fuel 

1 That portion of the total fuel that would actually burn under various environmental conditions. 

2 Fuel available for use in a motor vehicle, aircraft, or other motorized equipment. 

Available Resources 

1	 Resources assigned to an incident and available for assignment. 

see also:	 Active Resources
 

Allocated Resources
 

Assigned Resources
 

Average Annual Precipitation 

1	 The expected amount of annual rainfall. Average annual precipitation is an important component 

to determining the Keech-Bryam Drought Index (KBDI). 

Average Relative Humidity 

1	 Part of the National Fire Danger Rating System (NFDRS). The mathematical average of the 

maximum and minimum relative humidities measured at a fire weather station from one basic 

observation time to the next. 

Average Temperature 

1	 The mathematical average of the maximum and minimum dry-bulb temperatures measured at a 

fire weather station from one basic observation time to the next. 

Avoidance 

1	 A smoke emission control strategy that considers meteorological conditions when scheduling 

prescribed fires in order to avoid incursions into smoke sensitive areas. 

Awareness 

1	 The continual process of collecting, analyzing, and disseminating intelligence, information, and 

knowledge to allow organizations and individuals to anticipate requirements and to react 

effectively and safely. 

Azimuth 

1	 Horizontal angle or bearing of a point measured clockwise from true (astronomic) north. 

Azimuth Circle 

1	 A circle graduated in 360 degrees in a clockwise direction from true (astronomic) north. 

- B -

Back Azimuth 

Angle or bearing 180 degrees opposite of azimuth. 

October 2014	 Page 32 

1 
 

Glossary of Wildland Fire Terminology 

Backburn 

1	 Used in some localities to specify fire set to spread against the wind in prescribed burning. 

Backdraft 

1	 Instantaneous explosion or rapid burning of superheated gases that occurs when oxygen is 

introduced into an oxygen-depleted confined space. It may occur because of inadequate or 

improper ventilation procedures. 

Backfire 

1 A fire set along the inner edge of a fireline to consume the fuel in the path of a wildfire or change 

the direction of force of the fire's convection column. 

see also: Burn Out 

Backfire Torch 

1 A flame generating device (e.g., a fount containing diesel oil or kerosene and a wick, or a 

backpack pump serving a flame-jet). 

synonym: Burning Torch
 

see also: Drip Torch
 

Flame Thrower
 

Backfiring 

1	 A tactic associated with indirect attack, intentionally setting fire to fuels inside the control line to 

slow, knock down, or contain a rapidly spreading fire. Backfiring provides a wide defense 

perimeter and may be further employed to change the force of the convection column. 

Backfiring makes possible a strategy of locating control lines at places where the fire can be 

fought on the firefighter's terms. Except for rare circumstance meeting specified criteria, 

backfiring is executed on a command decision made through line channels of authority. 

Background Level 

1	 In air pollution control, the concentration of air pollutants in a definite area during a fixed period 

of time prior to the starting up, or the stoppage, of a source of emission under control. In toxic 

substances monitoring, the average presence in the environment, originally referring to naturallyoccurring phenomena. 

Backing Fire 

1 Fire spreading, or ignited to spread, into (against) the wind or downslope. A fire spreading on 

level ground in the absence of wind is a backing fire. 

2 That portion of the fire with slower rates of fire spread and lower intensity normally moving into 

the wind and/or down slope. Also called: heel fire. 

Backing Wind 

1	 Wind that changes direction in a counter clockwise motion. 

Backpack Pump 

1 A portable sprayer with hand-pump, fed from a liquid filled container fitted with straps, used 

mainly in fire and pest control. 

see also: Bladder Bag 

Baffle 

1	 A partitioned wall placed in vehicular or aircraft water tanks to reduce shifting of the water load 

when starting, stopping or turning. 

October 2014	 Page 33 
Glossary of Wildland Fire Terminology 

Ball Valve 

1	 A valve in which fluid flow is controlled by a ball with a hole drilled through it. In one position, 

fluid flows through the hole. When the valve is turned 90 degrees (1/4 turn) the hole is 

perpendicular to the flow and the ball stops the flow. Intermediate valve positions can be used to 

adjust the flow. 

Bambi Bucket ® 

1	 A collapsible bucket slung below a helicopter. Used to dip water from a variety of sources for fire 

suppression. 

Banking Snags 

1	 The act of throwing mineral soil about the base of an unlighted snag to prevent its being ignited 

by a surface fire. 

Barometer 

1	 An instrument for measuring the pressure of the atmosphere. The two principal types are the 

mercurial and the aneroid. 

Barometric Pressure 

1 Atmospheric pressure corrected for elevation. 

see also: Atmospheric Pressure
 

Barrier 

1	 Any obstruction to the spread of fire. Typically an area or strip devoid of combustible fuel. 

Base 

1	 The location at which primary logistics functions for an incident are coordinated and 

administered. There is only one base per incident. (Incident name or other designator will be 

added to the term "base.") The incident command post may be collocated with the base. 

2 The location of initial attack forces. 

see also: Camp
 

Base Area 

1	 Part of the National Fire Danger Rating System (NFDRS). An area representative of the major 

fire problems on a protection unit. Base fuel model and slope class are chosen from the base 

area. 

Base Fuel Model 

1	 Part of the National Fire Danger Rating System (NFDRS). A representation of the vegetative 

cover and fuel in a base area. Used in the calculation of fire danger rating. 

Base Manager (BCMG) 

1	 This ICS position is responsible for ensuring that appropriate sanitation, security, and facilities 

management services are provided at the Incident Base and reports to the Facilities Unit 

Leader. 

see also:	 Camp Manager
 

Facilities Unit
 

Base Observation Time 

1	 Part of the National Fire Danger Rating System (NFDRS). The time established to take the fire 

danger observations. It should be at the time of day when the fire danger is normally the 

highest. The usually agreed upon time is 1:00 pm standard time. This allows time to transmit 

observations and prepare forecasts. 

Base Station 

1 A fixed central radio dispatching station controlling movements of one or more mobile units. 

October 2014	 Page 34 
 

 

Glossary of Wildland Fire Terminology 

Baseline 

1	 In prescribed burning, the initial line of fire, usually set as a backing fire along a barrier or control 

line, which serves to contain subsequent burning operations. 

Basic Life Support (BLS) 

1	 Basic life support skills performed by an EMS practitioner or service, e.g. splinting, bandaging, 

oxygen administration, use of the AED. 

Batch Mix 

1	 Manually adding and mixing a concentrated chemical, such as liquid foam, or powdered or liquid 

retardant with water, or gelling agents with fuel, into solution in a tank or container. 

Bearing 

1	 The horizontal direction to or from any point, usually measured clockwise from true north, or 

some other reference point through 360 degrees. 

Beaufort Wind Scale 

1	 A system of estimating and reporting wind speeds. In its present form for international 

meteorological use it equates (a) Beaufort force (or Beaufort number), (b) wind speed, (c)
 

descriptive term, and (d) visible effects upon land objects or sea surf. 

BEHAVE 

1	 A system of interactive computer programs for modeling fuel and fire behavior, comprised of two 

systems: BURN and FUEL. 

Behavior 

1 An observable activity or action demonstrated by an individual in a particular context. 

see also: Competency
 

Belt Weather Kit 

1	 Belt-mounted case with pockets fitted for anemometer, compass, sling psychrometer, slide rule, 

water bottle, pencils, and book of weather report forms. Used to take weather observations to 

provide on-site conditions to the fire weather forecaster or fire behavior analyst. Observations 

include air temperature, wind speed and direction, and relative humidity. 

Benefits 

1	 Something that represents, promotes or enhances a desired outcome, being of positive value 

and contributing to the attainment of organizational goals. Benefits represent one end of the 

spectrum of outcomes from fire, with the opposite end being harm, loss or damage. 

see also: Fire Benefits 

Berm 

1 A ridge of soil and debris along the outside edge of a fireline, resulting from line construction. 

see also: Throw Out 

Best Available Control Measures (BACM) 

1	 An emission limitation action based on the maximum degree of emission reduction (considering 

energy, environmental, and economic impacts) achievable through application of production 

processes and available methods, systems, and techniques. 

see also: Reasonably Available Control Measures 

Blackline 

1	 Preburning of fuels adjacent to a control line before igniting a prescribed burn. Blacklining is 

usually done in heavy fuels adjacent to a control line during periods of low fire danger to reduce 

heat on holding crews and lessen chances for spotting across control line. In fire suppression, a 

blackline denotes a condition where there is no unburned material between the fireline and the 

fire edge. 

October 2014	 Page 35 
 

Glossary of Wildland Fire Terminology 

Bladder Bag 

1 A collapsible backpack portable sprayer made of neoprene or high-strength nylon fabric fitted 

with a pump. 

see also: Backpack Pump 

Blind Area 

1	 An area in which neither the ground nor its vegetation can be seen from a given observation 

point. 

Block Plan 

1	 A detailed prescription for treating a specified burning block with fire. 

Blow Down 

1 An area of previously standing timber which has been blown over by strong winds or storms. 

Blowup 

1	 Sudden increase in fireline intensity or rate of spread of a fire sufficient to preclude direct control 

or to upset existing suppression plans. Often accompanied by violent convection and may have 

other characteristics of a fire storm. 

see also:	 Extreme Fire Behavior
 

Fire Storm
 

Flare-up
 

Board of Review 

1	 A board or committee selected to review results of fire suppression action on a given unit or the 

specific action taken on a given fire. The board reviews the results in order to identify reasons 

for both good and poor action and to recommend or prescribe ways and means of doing an 

effective and efficient job. Reviews the results of a safety/accident investigation. 

Boiling Liquid Expanding Vapor Explosion (BLEVE) 

1 The failure of a closed container as a result of overpressurization caused by an external heat 

source. 

2 A major failure of a closed liquid container into two or more pieces when the temperature of the 

liquid is well above its boiling point at normal atmospheric pressure. 

Bole 

1	 The trunk of a tree. 

Bone Yard 

1	 A mop up term. To "bone yard" a fire means to systematically work the entire area, scraping 

embers off remaining fuel, feeling for heat with the hands, and piling unburned materials in 

areas cleared to mineral soil. 

2	 An area cleared to mineral soil for piling unburned fuels. 

Booster Hose 

1	 The most common type of hose attached and stored on wildland engine booster reels. The hose 

is made of neoprene and does not appreciably collapse when stored empty. 

Booster Pump 

1	 An intermediary pump for supplying additional lift in pumping water uphill past the capacity of 

the first pump. 

October 2014	 Page 36 
 

Glossary of Wildland Fire Terminology 

Booster Reel 

1	 A reel for the booster hose mounted on a fire engine, often supplied by the auxiliary pump. This 

reel usually carries a 1-inch (25 mm) or 3/4 inch (19 mm) hose and frequently contains an 

electric rewind mechanism. 

see also: Hose Reel 

Boundary Conditions 

1	 The temperature and relative humidity of the boundary layer. 

Boundary Layer 

1 The air in immediate contact with a fuel particle. 

2 That part of the lower atmosphere that is directly influenced by the presence of the earth's 

surface and responds to surface forcings with a time scale of about an hour or less. 

Boundary Value 

1	 The equilibrium moisture content (EMC) commensurate with the boundary conditions and 

precipitation events of the preceding 24 hours. 

Bowles Bag 

1	 A neoprene tank designed for attachment to the landing skid frame of a helicopter. It has a 

capacity of 80 to 100 gallons (303 to 378 liters) of water or retardant. 

Box Canyon 

1	 A steep-sided, dead end canyon. 

Branch 

1	 The organizational level having functional or geographical responsibility for major parts of 

incident operations. The branch level is organizationally between section and division/group in 

the operations section, and between section and unit in the logistics section. Branches are 

identified by roman numerals or by functional name (e.g. service, support). 

Break a Line 

1	 To insert a gate valve or some other device into a hose line. 

Break Coupling 

1	 To detach two pieces of hose by backing the swivel thread off the nipple thread. 

Break Left or Right 

1	 Means "turn" left or right. Applies to aircraft in flight, usually on the drop run, and when given as 

a command to the pilot, implies expectation of prompt compliance. 

Breakover 

1 A fire edge that crosses a control line or natural barrier intended to confine the fire. 

synonym: Slopover
 

British Thermal Unit (Btu) 

1	 Amount of heat required to raise 1 pound of water 1 degree Fahrenheit (from 59.50 to 60.50 F), 

measured at standard atmospheric pressure. 

Broadcast Burning 

1	 Prescribed burning activity where fire is applied generally to most or all of an area within well 

defined boundaries for reduction of fuel hazard, as a resource management treatment, or both. 

Brown and Burn 

1	 Application of herbicide to desiccate living vegetation prior to burning. 

October 2014	 Page 37 
 

 

Glossary of Wildland Fire Terminology 

Brownspot Control 

1	 Prescribed fire to control fungal infection (brown spot disease) of longleaf pine (Pinus palustris) 

in the "grass" (small seedling) stage. 

Brush 

1	 A collective term that refers to stands of vegetation dominated by shrubby, woody plants, or low 

growing trees, usually of a type undesirable for livestock or timber management. 

Brush Blade 

1	 Blade attachment with long teeth specially suited to ripping and piling brush with minimum 

inclusion of soil. Also called brush rake or root rake. 

Brush Fire 

1	 A fire burning in vegetation that is predominantly shrubs, brush, and scrub growth. 

Brush Hook 

1	 A heavy cutting tool designed primarily to cut brush at the base of the stem. Used in much the 

same way as an axe and having a wide blade, generally curved to protect the blade from being 

dulled by rocks. 

Brush Management 

1	 Manipulation of stands of brush by manual, mechanical, chemical, or biological means or by 

prescribed burning for the purpose of achieving land management objectives. 

Brush Patrol Unit 

1 Any light, mobile vehicular unit with limited pumping and water capacity for off-road operations. 

Bubble 

1	 The building block of foam; bubble characteristics of water content and durability influence foam 

performance. 

Bucket Drops 

1	 The dropping of fire retardants or suppressants from specially designed buckets slung below a 

helicopter. 

Bucking 

1	 Sawing through the bole of a tree after it has been felled. 

Build-up 

1 The cumulative effects of long-term drying on current fire danger.
 

2 The increase in strength of a fire management organization. 

3 The accelerated spreading of a fire with time. 

4 Towering cumulus clouds which may lead to thunderstorms later in the day. 

Buildup Index (BUI) 

1	 A relative measure of the cumulative effect of daily drying factors and precipitation on fuels with 

a ten-day timelag. 

Bulk Density 

1 Weight per unit volume. For fuels, this is usually expressed as pounds per cubic foot; for soils, 

grams per cubic centimeter. 

see also: Compactness 

October 2014	 Page 38 
 

Glossary of Wildland Fire Terminology 

Bumpup Method 

1 Progressive method of fireline construction on a wildfire without changing relative positions in 

the line. Work is begun with a suitable space between workers; whenever one worker overtakes 

another, all of those ahead move one space forward and resume work on the uncompleted part 

of the line. The last worker does not move ahead until work is completed in his/her space. 

Forward progress of the crew is coordinated by a crew boss. 

synonym: Moveup Method 

Burn 

1 An area burned over by wildland fire. 

2 A reference to a working fire. 

3 An injury to flesh caused by a cauterizing agent, heat from a fire, or a heated object 

a) First Degree Burn: A burn which causes only pain, redness, and swelling. 

b) Second Degree Burn: A burn in which the skin is blistered. 

c) Third Degree Burn: A flesh burn in which charring occurs. 

4 To be on fire. 

5 To consume fuel during rapid combustion. 

6 A fire in progress or under investigation. 

Burn Block 

1	 A discrete area within a larger prescribed or fire use project. 

Burn Boss 

1	 Person responsible for supervising a prescribed fire from ignition through mopup. 

Burn Out 

1 Setting fire inside a control line to consume fuel between the edge of the fire and the control 

line. 

see also: Backfire 

Burn Out Time 

1	 The duration of flaming and smoldering combustion phases at a specified point within a burn or 

for the whole burn, expressed in convenient units of time. 

Burn Patterns 

1	 The characteristic configuration of char left by a fire. In wildland fires burn patterns are 

influenced by topography, wind direction, length of exposure, and type of fuel. Definitions are 

scale-dependent: (1) They can be used to trace a fire's origin; (2) They are influenced by 

severity and intensity within a stand; (3) They describe the landscape mosaic. 

2	 Apparent and obvious design of burned material and the burning path from the area of origin. 

Burn Severity 

1	 A qualitative assessment of the heat pulse directed toward the ground during a fire. Burn 

severity relates to soil heating, large fuel and duff consumption, consumption of the litter and 

organic layer beneath trees and isolated shrubs, and mortality of buried plant parts. 

Burned Area Rehabilitation 

1 The post-fire activities prescribed and implemented to rehabilitate and restore fire damaged 

lands. 

see also: Rehabilitation 

Burning 

1	 Decomposition of material by the application of heat and oxidation. Also applied to propellants 

and other pyrotechnic mixtures, though the proper term there is "reacting". Also often an 

element of the crime of arson. 

October 2014	 Page 39 
 

 

Glossary of Wildland Fire Terminology 

Burning Ban 

1	 A declared ban on open air burning within a specified area, usually due to sustained high fire 

danger. 

Burning Conditions 

1	 The state of the combined factors of the environment that affect fire behavior in a specified fuel 

type. 

Burning Index 

1	 An estimate of the potential difficulty of fire containment as it relates to the flamelength at the 

head of the fire. 

2	 A relative number related to the contribution that fire behavior makes to the amount or effort 

needed to contain a fire in a specified fuel type. Doubling the burning index indicates that twice 

the effort will be required to contain a fire in that fuel type as was previously required, providing 

all other parameters are held constant. 

Burning Index Meter 

1	 A device used to determine the burning index for different combinations of burning index 

factors.
 

Burning Out 

1	 Setting fire inside a control line to consume fuel located between the edge of the fire and the 

control line. 

Burning Period 

1	 That part of each 24-hour period when fires spread most rapidly; typically from 10:00 AM to 

sundown. 

Burning Priority Rating 

1	 System of rating slash to indicate the treatment objective, whether or not burning is required to 

meet that objective, the fuel treatment necessary to achieve successful burning, and the time of 

year burning should occur. 

Burning Rate 

1	 Rate at which a propellant and other combustibles burn. 

Burning Rotation 

1	 The planned number of years between prescribed fires on a specified area. 

Burning Torch 

1 A flame generating device (e.g., a fount containing diesel oil or kerosene and a wick, or a 

backpack pump serving a flame-jet). 

synonym: Backfire Torch
 

see also: Drip Torch
 

Flame Thrower
 

Burnover 

1	 An event in which a fire moves through a location or overtakes personnel or equipment where 

there is no opportunity to utilize escape routes and safety zones, often resulting in personal 

injury or equipment damage. 

Buying Team 

1	 A team that supports incident procurement through the local administrative staff and is 

authorized to procure a wide range of services, supplies, and land and equipmental rentals. In 

addition, the Buying Team Leader has the responsibility of coordinating property accountability 

with the supply unit leader. 

October 2014	 Page 40 
 

 

Glossary of Wildland Fire Terminology 

Buys Ballot's Law 

1	 If a person stands with his back to the general wind, the high atmospheric pressure is found to 

his right in the Northern Hemisphere. The high pressure on the right moves clockwise and 

outward from the cell. The low pressure on the left moves counterclockwise and towards the 

center of the cell. This Law does not work in the presence of locally produced convective winds. 

- C -

Cache 

1	 A pre-determined complement of tools, equipment and/or supplies stored in a designated
 

location, available for incident use. 

Calculation of Probabilities 

1	 Evaluation of all factors pertinent to probable future behavior of a going fire and of the potential 

ability of available forces to perform fire suppression operations on a specified time schedule. 

Calibrated Airspeed 

1	 Indicated airspeed of an aircraft, corrected for position and instrument error. Equal to true
 

airspeed in standard atmosphere at sea level. 

Camp 

1	 A geographical site(s), within the general incident area, separate from the incident base, 

equipped and staffed to provide sleeping, food, water, and sanitary services to incident 

personnel.
 

see also:	 Base 

Camp Manager (BCMG) 

1	 This ICS position is responsible for ensuring that services, supplies, and non-technical 

coordination are provided within a camp and reports to the Facilities Unit Leader. There may be 

one or more camps per incident, each with a Camp Manager. 

see also:	 Base Manager
 

Facilities Unit
 

Candling 

1 The burning of the foliage of a single tree or a small group of trees, from the bottom up. 

synonym: Torching
 

Canopy 

1	 The stratum containing the crowns of the tallest vegetation present (living or dead), usually 

above 20 feet. 

Carbon Dioxide (CO2) 

1	 A colorless, odorless, nonpoisonous gas, which results from fuel combustion and is normally a 

part of the ambient air. 

Carbon Monoxide (CO) 

1	 A colorless, odorless, poisonous gas produced by incomplete fuel combustion. 

Carcinogen 

1	 Any substance that can cause or contribute to the production of cancer. 

Cardinal Altitudes 

1	 Odd or "even" thousand-foot (305 m) altitudes or flight levels. E.g., 5,000, 6,000, 7,000; FL 250, 

FL 260, and FL 270. 

October 2014	 Page 41 
 

 

 

Glossary of Wildland Fire Terminology 

Cardinal Directions 

1	 North, south, east, west; used for giving directions and information from the ground or air in 

describing the fire (e.g., the west flank or east flank, not right flank or left flank). 

Cargo Chute 

1	 A parachute designed and rigged for dropping equipment and supplies from an aircraft. 

Cargo Compartment 

1	 An internal area of an aircraft specifically designed to carry baggage or cargo. 

Cargo Drop 

1	 Dropping of equipment or supplies, with or without a parachute, from an aircraft in flight. 

Cargo Hook 

1	 Mechanically and electrically operated hook attached to the bottom of a helicopter to which a 

sling load is attached. 

Cargo Net 

1 Net attached to the cargo hook of a helicopter, used to carry cargo. Also called cargo sling. 

Cargo Rack 

1	 Externally mounted rack for transporting supplies or cargo aboard a helicopter. 

Carousel Hook 

1	 A remote hook attached to the end of a longline. It has four or more individual hooks which can 

be independently released, allowing the pilot to fly cargo loads to different locations without 

landing. 

Carried Wet 

1	 Booster hose carried full of water during mild weather to speed discharge of water on fire
 

without filling or priming from tank. 

Carrier Fuels 

1	 The fuels that support the flaming front of the moving fire. 

Casual 

1 A person hired and compensated under the Pay Plan for Emergency Workers. 

synonym: Administratively Determined
 

see also: Emergency Firefighter
 

Category Day 

1	 A numerical index related to the ability of the atmosphere to disperse smoke. Different agencies 

use different scales [e.g., in South Carolina, the current scale is based on ventilation factor and 

ranges from 1 (poor) to 5 (excellent)]. 

Catface 

1	 Defect on the surface of a tree resulting from a wound where healing has not re-established the 

normal cross-section. 

Ceiling 

1	 Height above the earth's surface of the lowest layer of clouds or obscuring phenomena aloft that 

is not classified as a thin layer or partial obscuration, that together with all lower clouds or 

obscuring phenomena covers more than half the sky as detected from the point of observation. 

2	 Maximum height of a temporary flight restriction (TFR). 

October 2014	 Page 42 
Glossary of Wildland Fire Terminology 

Celsius 

1	 A temperature scale with 0° as the freezing point of water and 100° as the boiling point of water 

at sea level. 

Center Firing 

1	 Method of broadcast burning in which fire is ignited in the center of the area to create a strong 

draft; additional fires are then ignited progressively nearer the outer control lines (sometimes in 

one step) as indraft increases so as to draw the flames and smoke toward the center. 

Centrifugal Pump 

1	 Pump which expels water by centrifugal force through the ports of a circular impeller rotating at 

high speed. With this type of pump, the discharge line may be shut off while the pump is running 

without damaging the pump or hose. 

Certifying Official 

1	 The agency official at the home unit who is responsible for authorizing and granting position 

certification per agency policy. The agency official is responsible for completing the agency 

certification block located on the inside front cover of a Position Task Book. 

see also:	 Agency Certification
 

Home Unit
 

Position Task Book
 

Chain 

1	 Unit of measure in land survey, equal to 66 feet (20 M) (80 chains equal 1 mile). Commonly 

used to report fire perimeters and other fireline distances, this unit is popular in fire management 

because of its convenience in calculating acreage (e.g., 10 square chains equal one acre). 

Chain Lightning 

1	 Lightning in a long zigzag or apparently broken line. 

Chain of Command 

1	 A series of management positions in order of authority. 

Char 

1	 Carbonaceous material formed by incomplete combustion of an organic material, most
 

commonly wood; remains of burned materials. 

2	 In fire simulation, a darkened area within the fire perimeter; usually indicates fire has already 

passed through; usually created by an opaque material blocking out a selected portion of basic 

scene illumination. 

Char Height 

1	 The vertical distance above ground scorched or blackened on a tree bole. 

Charged Line 

1 Hose filled with water under pressure and ready to use. 

synonym: Live Line
 

see also: Live Reel
 

Chase Truck 

1 Vehicle that carries crew gear, supplies, and operational equipment for initial/extended attack. 

Check Line 

1	 A temporary fireline constructed at right angles to the control line and used to hold a backfire in 

check as a means of regulating the heat or intensity of the backfire. 

October 2014	 Page 43 
Glossary of Wildland Fire Terminology 

Check Valve 

1	 A valve that permits flow of liquid through a hose or pipe in one direction but prevents a return 

flow. Uses include the prevention of backflow on uphill hose lays, loss of prime with centrifugal 

pumps and chemical contamination in fire chemical mixing systems. 

Check-in 

1	 The process whereby resources first report to an incident. Check-in locations include incident 

command post (ICP), base or camps, staging areas, helibases, or direct to a tactical 

assignment. 

see also: Reporting Locations 

Chevron Burn 

1	 Burning technique in which lines of fire are started simultaneously from the apex of a ridge point, 

and progress downhill, maintaining position along the contour; used in hilly areas to ignite ridge 

points or ridge ends. 

Chief 

1	 The ICS title for individuals responsible for command of functional sections: Operations, 

Planning, Logistics, and Finance/Administration. 

Chief of Party 

1	 The chief of party is responsible to the sending unit dispatcher until destination is reached. 

Chief of party is responsible for all traveling personnel assigned on the manifest list. 

Circumstantial Evidence 

1	 Testimony or information not based on actual personal knowledge or observation, but 

dependent on inference of other facts or experience. For example, testimony that defendant’s 

cigarette lighter was found in ashes of a fire. 

Cirrus 

1	 A form of high cloud, composed of ice crystals, which seldom obscures the sun. 

Claims Specialist (CLMS) 

1	 Person responsible for handling all claims, other than injury, against the incident. 

Class A Foam 

1	 Foam intended for use on Class A or woody fuels; made from hydrocarbon-based surfactant, 

therefore lacking the strong filming properties of Class B foam, but possessing excellent wetting 

properties. 

Class B Foam 

1	 Foam designed for use on Class B or flammable liquid fires; made from fluorocarbon-based 

surfactants, therefore capable of strong filming action, but incapable of efficient wetting of Class 

A fuels. 

Class I Areas (Air Quality) 

1	 Geographic areas designed by the Clean Air Act subject to the most stringent restrictions on 

allowable increment of air quality deterioration. Class I areas include Forest Service 

wildernesses and nation memorial parks over 5,000 acres, National Parks exceeding 6,000 

acres, international parks, as well as other designated lands. 

Class II Areas (Air Quality) 

1 All areas of the country not designated Class I, including everything from non-Class I areas to 

urban areas. A greater amount of air pollution can be added to these areas than Class I. 

October 2014	 Page 44 
Glossary of Wildland Fire Terminology 

Class of Fire 

1	 As to kind of fire for purpose of using a proper extinguisher: 

Class A - Fires involving ordinary combustible materials (such as wood, cloth, paper, rubber, 

and many plastics) requiring the heat absorbing (cooling) effects of water, water solutions, or the 

coating effects of certain dry chemicals, which retard combustion. 

Class B - Fires involving flammable or combustible liquids, flammable gases, greases, and 

similar materials where extinguishment is most readily secured by excluding air (oxygen), 

inhibiting the release of combustible vapors, or interrupting the combustion chain reaction. 

Class C - Fires involving live electrical equipment where safety to the operator requires the use 

of electrically nonconductive extinguishing agents. 

Class D - Fires involving certain combustible metals (such as magnesium, titanium, zirconium, 

sodium, potassium, etc.) requiring a heat absorbing extinguishing medium not reactive with 

burning metals. 

see also: Size Class of Fire 

Clean Air Act 

1	 A federal law enacted to ensure that air quality standards are attained and maintained. Initially 

passed by Congress in 1963, it has been amended several times. 

Clear Text 

1	 The use of plain English in radio communications transmissions. No Ten Codes or agency 

specific codes are used when using Clear Text.
 

Climate 

1	 The prevalent or characteristic meteorological conditions of any place or region, and their 

extremes. 

Climate Class 

1	 In NFDRS, one of four classifications of general climate of an area. 

Climatological Breakpoint 

1	 Points on the cumulative distribution of one fire weather/fire danger index without regard to 

associated fire occurrence/business. 

Clock Method 

1	 Means of establishing a flight path to a target on a fire by referring to clock directions from the 

aircraft's present location, with the nose of the aircraft pointing at 12:00. 

Closed Area 

1	 An area in which specified activities or entry are temporarily restricted to reduce risk of humancaused fires or to mitigate the risk to human health or safety by potential or on-going wildland 

fires. 

Closure 

1	 An administrative action limiting or prohibiting access to a specific geographic or jurisdictional 

area for the purposes of reducing wildfire or the risk it poses to life, property, and/or resources. 

Example of use: "Pursuant to 36 C.F.R. 261.50 (a) and (b), it is hereby ordered that the 

prohibitions hereinafter set forth apply to the general forest area of the Ozark-St. Francis 

National Forests until further notice." 

see also: Restrictions 

Cloud 

1	 A visible cluster of minute water/ice particles in the atmosphere. 

October 2014	 Page 45 
 

Glossary of Wildland Fire Terminology 

Cloudy 

1	 Adjective class representing the degree to which the sky is obscured by clouds. In weather 

forecast terminology, expected cloud cover of about 0.7 or more warrants use of this term. In 

the National Fire Danger Rating System, 0.6 or more cloud cover is termed "cloudy." 

Cold Front 

1	 The leading edge of a relatively cold air mass which displaces warmer air, causing it to rise. If 

the lifted air contains enough moisture, cloudiness, precipitation and even thunderstorms may 

result. As fronts move through a region, in the Northern Hemisphere, the winds at a given 

location will experience a marked shift in direction. Ahead of an approaching cold front, winds 

will usually shift gradually from southeast to south, and on to southwest. As a cold front passes, 

winds shift rapidly to west, then northwest. Typical cold front windspeeds range between 15 and 

30 mph but can be much higher. 

Cold Line 

1	 Fireline that has been controlled. The fire has been mopped up for a safe distance inside the 

line and can be considered safe to leave unattended. 

Cold Trailing 

1	 A method of controlling a partly dead fire edge by carefully inspecting and feeling with the hand 

for heat to detect any fire, digging out every live spot, and trenching any live edge. 

Collective Control 

1 Controls the pitch angle of the main (helicopter) rotor blades. Used as primary altitude control. 

Colonizer 

1	 Species of vegetation that establish on a burned (or otherwise denuded) site from seed. 

Combination Nozzle 

1	 A nozzle is designed to provide either a solid stream or a fixed spray pattern suitable for
 

applying water, wet water or foam solution. Also called: Adjustable Fog Nozzle.
 

Combination Nozzle Tip 

1	 Two attached straight stream nozzle tips of different orifice size used to increase or restrict 

water flow. 

Combustion 

1	 The rapid oxidation of fuel in which heat and usually flame are produced. Combustion can be 

divided into four phases: preignition, flaming, smoldering, and glowing. 

Combustion Efficiency 

1	 The relative amount of time a fire burns in the flaming phase of combustion, as compared to 

smoldering combustion. A ratio of the amount of fuel that is consumed in flaming combustion 

compared to the amount of fuel consumed during the smoldering phase, in which more of the 

fuel material is emitted as smoke particles because it is not turned into carbon dioxide and 

water. 

Combustion Period 

1	 Total time required for a specified fuel component to be completely consumed. 

Combustion Rate 

1 Rate of heat release per unit of burning area per unit of time. 

see also: Reaction Intensity
 

Command 

1	 The act of directing, and/or controlling resources by virtue of explicit legal, agency, or delegated 

authority. 

October 2014	 Page 46 
 

Glossary of Wildland Fire Terminology 

Command Climate 

1	 The working environment within the influence of a particular leader or chain of command. The 

command climate is based on the subordinates' understanding of how they are expected to 

perform, how they are treated, and how they must conform to the leader's style. 

Command Presence 

1	 How leaders present themselves to others. The personal attributes and traits that determine 

whether leaders are worthy of trust and respect from their subordinates. 

Command Staff 

1	 The command staff consists of the information officer, safety officer and liaison officer. They 

report directly to the incident commander and may have an assistant or assistants, as needed. 

Commercial Forest Land 

1	 Land that is producing, or is capable of producing, crops of industrial wood and is not withdrawn 

from timber use by statute or administrative regulation. 

Commissary 

1	 Supply of items such as candy, tobacco products, toilet items, and work clothes that are made 

available for sale to all incident personnel. 

Commissary Manager (CMSY) 

1	 Person responsible to the time unit leader for operating the commissary at an incident base or 

camp. 

Communications Unit 

1	 An organizational unit in the Logistics Section responsible for providing and maintaining 

communication services at an incident. May also be a facility (e.g., a trailer or mobile van) used 

to provide the major part of an incident communications center. 

Communications Unit Leader (COML) 

1 The ICS position responsible for supervising the Communications Unit. Reports to the Service 

Branch Director or Logistics Section Chief. 

see also: Communications Unit 

Community Wildfire Protection Plan (CWPP) 

1	 A plan developed in the collaborative framework established by the Wildland Fire Leadership 

Council and agreed to by state, tribal, and local government, local fire department, other 

stakeholders and federal land management agencies managing land in the vicinity of the 

planning area. A Community Wildfire Protection Plan (CWPP) identifies and prioritizes areas for 

hazardous fuel reduction treatments and recommends the types and methods of treatment on 

Federal and non-Federal land that will protect one or more at-risk communities and essential 

infrastructure and recommends measures to reduce structural ignitability throughout the at-risk 

community. A CWPP may address issues such as wildfire response, hazard mitigation, 

community preparedness, or structure protection – or all of the above. 

Compact 

1	 A formal working agreement among agencies to obtain mutual aid. 

Compactness 

1 Spacing between fuel particles. 

see also: Bulk Density
 

Company 

1	 Any piece of (fire) equipment having a full complement of personnel. 

October 2014	 Page 47 
 

 

Glossary of Wildland Fire Terminology 

Compare and Contrast 

1	 An investigative technique that involves comparing same sized indicators within a category at 

separate locations; looking for either differences or similarities in appearance. 

Compass Rose 

1	 A circle, graduated in degrees, printed on some charts or marked on the ground at an airport or 

heliport. It is used as a reference to either true or magnetic direction. 

Compensation/Claims Unit 

1	 Functional unit within the Finance/Administration Section responsible for the overall 

management and direction of all Compensation-for-Injury and Claims Specialists assigned to 

the incident. 

Compensation/Claims Unit Leader (COMP) 

1 The ICS position responsible for supervising the Compensation/Claims Unit. Reports to the 

Finance/Administration Section Chief. 

see also: Compensation/Claims Unit 

Compensation-for-Injury Manager 

1	 Person responsible to the Compensation/Claims Unit Leader for administrative matters arising 

from serious injuries and fatalities occurring on the incident. 

Competency 

1 A broad description that groups core behaviors necessary to perform a specific function. 

see also: Behavior
 

Competent Ignition Source 

1	 A source of heat that is capable of kindling a wildfire. It may be in the form of a mechanical or 

electrical spark, glowing ember, open flame, chemical reaction or friction. 

Complex Incident 

1	 Two or more individual incidents located in the same general area which are assigned to a 

single incident commander or unified command. 

Compressed Air Foam Systems (CAFS) 

1	 A generic term used to describe foam systems consisting of an air compressor (or air source), a 

water pump, and foam solution. 

Computed Gross Weight 

1	 Term used in calculating from performance charts the permissible helicopter payload at which a 

helicopter is capable of hovering in ground effect or hovering out of ground effect, based on 

pressure altitude and air temperature. 

Concentrate 

1	 A substance that has been concentrated; specifically, a liquid that has been made denser, as by 

the removal of some of its water. 

Conceptual Model 

1 A model that is a diagram or description of a set of relationships between factors that describe 

how a system works, such as an ecological model. 

see also: Model 

Condensation 

1	 The process by which a gas becomes a liquid. 

October 2014	 Page 48 
 

 

Glossary of Wildland Fire Terminology 

Condition Class 

1	 Depiction of the degree of departure from historical fire regimes, possibly resulting in 

alternations of key ecosystem components. These classes categorize and describe vegetation 

composition and structure conditions that currently exist inside the Fire Regime Groups. Based 

on the coarse-scale national data, they serve as generalized wildfire rankings. The risk of loss of 

key ecosystem components from wildfires increases from Condition Class 1 (lowest risk) to 

Condition Class 3 (highest risk). 

synonym: Fire Regime Current Condition Class 

Condition of Vegetation 

1	 Stage of growth or degree of flammability of vegetation that forms part of a fuel complex. 

Herbaceous stage is at times used when referring to herbaceous vegetation alone. In grass 

areas minimum qualitative distinctions for stages of annual growth are usually green, curing, 

and dry or cured. 

Conduction 

1	 Heat transfer through a material from a region of higher temperature to a region of lower 

temperature. 

Confinement 

1	 The strategy employed in appropriate management responses where a fire perimeter is
 

managed by a combination of direct and indirect actions and use of natural topographic
 

features, fuel, and weather factors. 

Conflagration 

1	 A raging, destructive fire. Often used to connote such a fire with a moving front as distinguished 

from a fire storm. 

Conflagration Threat 

1	 Likelihood that a wildfire capable of causing considerable damage will occur. 

Consistency (Foam) 

1	 Uniformity and size of bubbles. 

Constant Danger 

1	 Resultant of all fire danger factors that are relatively unchanging in a specific area (e.g., 

resource values at risk, topography, fuel type, exposure to prevailing wind). 

Consumption 

1	 The amount of a specified fuel type or strata that is removed through the fire process, often 

expressed as a percentage of the preburn weight. 

Contained 

1	 The status of a wildfire suppression action signifying that a control 

line has been completed around the fire, and any associated spot fires, which can reasonably 

be expected to stop the fire’s spread. 

see also: Containment 

Containment 

1	 The status of a wildfire suppression action signifying that a control line has been completed 

around the fire, and any associated spot fires, which can reasonably be expected to stop the 

fire’s spread. 

2 The act of controlling hazardous spilled or leaking materials. 

see also: Contained
 

October 2014	 Page 49 
 

 

Glossary of Wildland Fire Terminology 

Continental Climate 

1	 Climate that is characteristic of the interior of a land mass of continental size, marked by large 

annual diurnal and day-to-day ranges of temperature, low relative humidity and irregular 

precipitation. 

Contingency Actions 

1	 A back-up plan of action when actions described in the primary plan are no longer appropriate. 

Contingency actions are required to be taken when the result exceeds its intent. Actions are 

taken to return the project to its intended design. 

Contingency Plan 

1	 The portion of a prescribed fire plan, incident action plan, or implementation plan that identifies 

possible but unlikely events and the contingency resources needed to mitigate those events. 

Contingency Resources 

1	 Planned and identified fire suppression personnel and equipment that mitigate possible but 

unlikely events that exceed or are expected to exceed holding resource capabilities. 

Contour Map 

1	 A map having lines of equal elevation that represent the land surface (Topographic). 

Control Force 

1	 Personnel and equipment used to control a fire. 

Control Line 

1	 An inclusive term for all constructed or natural barriers and treated fire edges used to control a 

fire. 

Control Time 

1	 The time a fire is declared controlled. 

Controlled 

1	 The completion of control line around a fire, any spot fires therefrom, and any interior islands to 

be saved; burned out any unburned area adjacent to the fire side of the control lines; and cool 

down all hot spots that are immediate threats to the control line, until the lines can reasonably 

be expected to hold under the foreseeable conditions. 

Controlled Airspace 

1	 Airspace of defined dimensions within which air traffic control service is provided to IFR and 

VFR flights in accordance with the airspace classification. 

Controlling Nozzle 

1	 Shut-off nozzle that permits the nozzle operator to open or close the nozzle or adjust the pattern 

of the stream. 

Convection 

1	 The transfer of heat by the movement of a gas or liquid; convection, conduction, and radiation 

are the principal means of energy transfer. 

2	 As specialized in meteorology, atmospheric motions that are predominantly vertical in the 

absence of wind (which distinguishes this process from advection), resulting in vertical transport 

and mixing of atmospheric properties. 

Convection Column 

1	 The rising column of gases, smoke, fly ash, particulates, and other debris produced by a fire. 

The column has a strong vertical component indicating that buoyant forces override the ambient 

surface wind. 

see also: Smoke Plume 

October 2014	 Page 50 
 

 

Glossary of Wildland Fire Terminology 

Convective Activity 

1	 General term for manifestations of convection in the atmosphere, alluding particularly to the 

development of convective clouds and resulting weather phenomena, such as showers, 

thunderstorms, squalls, hail, tornadoes, etc. 

Convective-lift Fire Phase 

1	 The phase of a fire when most of the emissions are entrained into a definite convection column. 

Convergence 

1	 The term for horizontal air currents merging together or approaching a single point, such as at 

the center of a low pressure area producing a net inflow of air. When this occurs in the lower 

atmosphere, the excess air is removed by rising air currents. Expansion of the rising air above a 

convergence zone results in cooling, which in turn often gives condensation (clouds) and 

sometimes precipitation. 

Convergence Zone 

1 The area of increased flame height and fire intensity produced when two or more fire fronts burn 

together. 

2 In fire weather, that area where two winds come together from opposite directions and are 

forced upwards often creating clouds and precipitation. 

Conversion Burning 

1	 Burning an area where brush has excluded forest reproduction to prepare the area for tree 

planting. 

Co-op Fire 

1	 Refers to federal, state, and local cooperative fire programs. 

Cooperating Agency 

1	 An agency supplying assistance including but not limited to direct tactical or support functions or 

resources to the incident control effort (e.g. Red Cross, law enforcement agency, telephone 

company, etc.). 

see also:	 Agency
 

Agency Representative
 

Assisting Agency
 

Supporting Agency
 

Cooperative Fire Protection (CFP) 

1	 A staff unit within the branch of State and Private Forestry or Aviation and Fire Management in 

the National Forest System, USDA Forest Service, that coordinates cooperative fire activities. 

Cooperator 

1	 A federal, tribal, state, or local agency that participates with another agency(s) in planning and 

conducting fire or emergency management projects and activities. 

see also:	 Agency
 

Agency Representative
 

Assisting Agency
 

Cooperating Agency
 

Supporting Agency
 

Coordinated Resource Management 

1	 A process that directly involves everyone concerned with resource management in a given 

planning area. 

Coordinates 

1	 The intersection of lines of reference, usually expressed in degrees/minutes/seconds of latitude 

and longitude, used to determine or report position or location. 

October 2014	 Page 51 
 

 

Glossary of Wildland Fire Terminology 

Coordination 

1	 The process of systematically analyzing a situation, developing relevant information, and 

informing appropriate command authority of viable alternatives for selection of the most effective 

combination of available resources to meet specific objectives. The coordination process (which 

can be either intra- or interagency) does not involve dispatch actions. However, personnel 

responsible for coordination may perform command or dispatch functions within limits 

established by specific agency delegations, procedures, legal authority, etc. 

Coordination Center 

1	 Term used to describe any facility that is used for the coordination of agency or jurisdictional 

resources in support of one or more incidents. 

Coriolis Force 

1	 An apparent force due to the rotation of the earth that causes a deflection of air to the right in 

the Northern Hemisphere and to the left in the Southern Hemisphere. This force maximizes at 

the poles and is essentially zero at the equator. 

Corrosion 

1	 Result of chemical reaction between a metal and its environment (i.e., air, water, and impurities 

in same). 

Cost Sharing Agreements 

1	 Agreements that document the financial responsibility for incident resource costs, possibly 

identifying requirements of other party payments.
 

Cost Unit 

1	 Functional unit within the Finance/Administration Section responsible for collecting all cost data, 

performing cost effectiveness analyses, and providing cost estimates and cost saving advice. 

Cost Unit Leader (COST) 

1 The ICS position responsible for supervising the Cost Unit. Reports to the 

Finance/Administration Section Chief. 

see also: Cost Unit
 

Council Tool 

1 Long-handled combination rake and cutting tool, the blade of which is constructed of a single 

row of three or four sharpened teeth. Also called fire rake, council rake. 

see also: Rich Tool 

Counter Fire 

1 Fire set between main fire and backfire to hasten spread of backfire. Also called draft fire. 

2 Emergency firing to stop, delay, or split a fire front, or to steer a fire. Also called draft fire. 

Coupling 

1 Device that connects the ends of adjacent hoses or other components of hose.
 

see also: Adapter
 

Course 

1	 In aviation, the intended direction of horizontal flight. 

Cover 

1	 The area on the ground covered by the combined aerial parts of plants expressed as a percent 

of the total area. 

Cover Type 

1	 The designation of a vegetation complex described by dominant species, age, and form. 

October 2014	 Page 52 
 

 

 

Glossary of Wildland Fire Terminology 

Coverage Level 

1	 Recommended amount of aerially applied retardant keyed to the NFDRS fuel models and/or fire 

behavior models. Coverage level 2 represents 2 gallons of retardant per hundred square feet. 

Levels range from 1 to 6 for most fuel models. A coverage level of greater than 6 is for heavy 

fuels. The levels can be adjusted for fire behavior. 

Coyote Tactics 

1	 A progressive line construction duty involving self-sufficient crews which build fire line until the 

end of the operational period, remain at or near the point while off duty, and begin building 

fireline the next operational period where they left off. 

Crazing 

1	 Fine cracking of glass, usually from heat of fire. 

Creeping Fire 

1	 Fire burning with a low flame and spreading slowly. 

Crew 

1	 An organized group of firefighters under the leadership of a crew boss or other designated 

official. 

Crew Boss (CRWB) 

1	 A person in supervisory charge of usually 16 to 21 firefighters and responsible for their
 

performance, safety, and welfare.
 

Crew Shuttle 

1	 Transportation of fireline personnel to and/or from assigned fireline locations. 

Crew Transport 

1 Any vehicle capable of transporting a specified number of personnel in a specified manner. 

Criteria Pollutants 

1	 Pollutants deemed most harmful to public health and welfare and that can be monitored 

effectively. They include carbon monoxide (CO), lead (Pb), nitrogen oxides (Nox), sulfur dioxide 

(SO2), ozone (O3), particulate matter (PM) of aerodynamic diameter less than or equal to 10 

micrometers (PM10) and particulate matter of aerodynamic diameter less than or equal to 2.5 

micrometers (PM2.5). 

Critical Burnout Time 

1	 Total time a fuel can burn and continue to feed energy to the base of a forward-traveling 

convection column. 

Critical Incident Stress Debriefing (CISD) 

1	 The process in which teams of professional and peer counselors provide emotional and 

psychological support to incident personnel who are or have been involved in a critical (highly 

stressful) incident. 

Cross Shot 

1	 Intersecting lines of sight from two points to the same object, frequently used to determine 

location of a fire from lookouts. Also called cross bearing. 

Crown Consumption 

1	 Combustion of the twigs, and needles or leaves of a tree during a fire. 

Crown Cover 

1	 The ground area covered by the crown of a tree as delimited by the vertical projection of its 

outermost perimeter. 

October 2014	 Page 53 
Glossary of Wildland Fire Terminology 

Crown Fire 

1	 A fire that advances from top to top of trees or shrubs more or less independent of a surface 

fire. Crown fires are sometimes classed as running or dependent to distinguish the degree of 

independence from the surface fire. 

Crown Out 

1	 A fire that rises from ground into the tree crowns and advances from tree top to tree top. To 

intermittently ignite tree crowns as a surface fire advances. 

Crown Ratio 

1	 The ratio of live crown to tree height. 

Crown Scorch 

1	 Browning of needles or leaves in the crown of a tree or shrub caused by heating to lethal 

temperature during a fire. Crown scorch may not be apparent for several weeks after the fire. 

Crown Scorch Height 

1	 The height above the surface of the ground to which a tree canopy is scorched. 

Crowning Potential 

1	 A probability that a crown fire may start, calculated from inputs of foliage moisture content and 

height of the lowest part of the tree crowns above the surface. 

Cumulonimbus 

1	 The ultimate growth of a cumulus cloud into an anvil-shaped cloud with considerable vertical 

development, usually with fibrous ice crystal tops, and usually accompanied by lightning, 

thunder, hail, and strong winds. 

Cumulus 

1	 A principal low cloud type in the form of individual cauliflower-like cells of sharp non-fibrous 

outline and less vertical development than cumulonimbus. 

Cup Trench 

1	 A fireline trench on the downhill side of fire burning on steep slopes that is supposed to be built 

deep enough to catch rolling firebrands that could otherwise start fire below the fireline. A high 

berm on the outermost downhill side of the trench helps the cup trench catch material. Also 

called gutter trench. 

Cupping Indicators 

1	 A concave or cup-shaped depression on grass stem ends, small stumps, and terminal ends of 

brush and tree limbs. 

Curb Weight 

1	 Weight of a truck empty (without payload and driver) but ready to drive, including a full fuel tank, 

cooling system, crankcase, tools, spare wheel, and all other equipment specified as standard. 

Cured 

1	 In the 1978 version of NFDRS, the herbaceous stage when herbaceous fuel moisture falls to 

30% or less. 

Curing 

1	 Drying and browning of herbaceous vegetation due to mortality or senescence, and also loss of 

live fuel moisture content of woody fuel following mechanically-caused mortality (e.g., woody 

debris slash.) 

October 2014	 Page 54 
 

 

 

Glossary of Wildland Fire Terminology 

Curling Indicators 

1	 Green leaves on succulent, uncured vegetation which bends and curls inwards towards the heat 

source. 

- D -

Daily Activity Level 

1	 Part of the National Fire Danger Rating System (NFDRS). In fire danger rating, a subjective 

estimate of the degree of activity of a potential human-caused fire source relative to that which 

is normally experienced. Five activity levels are defined: none, low, normal, high, and extreme. 

Damage Differential 

1	 The difference in change or damage that occurs to similar objects after they are exposed to fire 

of differing intensity and/or duration. The underlying principle behind the interpretation of burn 

pattern. 

Damage Differential Indicators 

1	 The amount of fire related destruction to combustible objects determined by comparing
 

opposing sides of an object.
 

Dead Fuels 

1	 Fuels with no living tissue in which moisture content is governed almost entirely by absorption or 

evaporation of atmospheric moisture (relative humidity and precipitation). 

Debris Burning Fire 

1	 In fire suppression terminology, a fire spreading from any fire originally ignited to clear land or 

burn rubbish, garbage, crop stubble, or meadows (excluding incendiary fires). 

2	 In prescribed fire terminology, a fire used to dispose of scattered, piled, or windrowed dead 

woody fuel, generally in the absence of a merchantable overstory. Its purpose is to reduce 

unsightly fuel concentrations, or consume unwanted natural fuels to facilitate subsequent 

resource management or land use actions on the area. 

Deck 

1	 The helibase operational area that includes the touchdown pad, safety circle, hover lanes, and 

external cargo transport area. 

Deck Coordinator (DECK) 

1	 Person responsible to the helibase manager for coordinating the movement of personnel and 

cargo at the helibase landing area. 

Deepening 

1	 As it refers to atmospheric pressure, a decrease in the central pressure of a low. This is usually 

accompanied by intensification of the cyclonic circulation (counter-clockwise wind flow around 

the low). 

Deep-Seated Fire 

1 A fire burning far below the surface in duff, mulch, peat, or other combustibles as contrasted 

with a surface fire. 

2 A fire that has gained headway and built up heat in a structure so as to require greater cooling 

for extinguishment. 

October 2014	 Page 55 
Glossary of Wildland Fire Terminology 

Deflagration 

1 Chemical decomposition by burning material in which the reaction is less than sonic velocity, for 

example, low explosives. 

2 A burning with great heat and intense light. 

Degradation 

1	 In a discussion of fire retardant slurries, deterioration of viscosity. 

Delayed Aerial Ignition Devices (DAID) 

1	 Polystyrene balls, 1.25 inches in diameter, containing potassium permanganate. The balls are 

fed into a dispenser, generally mounted in a helicopter, where they are injected with a waterglycol solution and then drop through a chute leading out of the helicopter. The chemicals react 

thermally and ignite in 25-30 seconds. The space between ignition points on the ground is 

primarily a function of helicopter speed, gear ratio of the dispenser, and the number of chutes 

used (up to four). 

see also:	 Aerial Ignition Device 

Helitorch 

Ping-Pong Ball System 

Plastic Sphere Dispenser 

Delegation of Authority 

1	 A statement provided to the incident commander by the agency executive delegating authority 

and assigning responsibility. The delegation of authority can include objectives, priorities, 

expectations, constraints and other considerations or guidelines as needed. Many agencies 

require written delegation of authority to be given to incident commanders prior to their 

assuming command on larger incidents. 

Demobilization 

1	 Release of resources from an incident in strict accordance with a detailed plan approved by the 

incident commander. 

Demobilization Unit 

1	 Functional unit within the planning section responsible for assuring orderly, safe and efficient 

demobilization of incident resources. 

Demobilization Unit Leader (DMOB) 

1 The ICS position responsible for supervising the Demobilization Unit. Reports to the Planning 

Section Chief. 

see also: Demobilization Unit 

Dense Layer 

1	 A layer of clouds whose ratio of dense sky cover to total sky cover is more than one-half. 

Dense Sky Cover 

1	 Sky cover that prevents detection of higher clouds or the sky above it. 

Density (Foam) 

1	 The ratio of the original volume of the nonaerated foam solution to the resultant volume of 

foam. The inverse of expansion. 

Density Altitude 

1	 Pressure altitude corrected for temperature deviations from standard atmosphere. Used as an 

index to aircraft performance characteristics such as take-off distance and rate of climb. Density 

altitude bears the same relation to pressure altitude as true altitude does to indicated altitude. 

October 2014	 Page 56 
 

Glossary of Wildland Fire Terminology 

Departure from Average Greenness (DA) 

1	 An NDVI-derived image of vegetation greenness compared to its average greenness for the 

current week of the year. 

Depth of Burn (DOB) 

1	 The reduction in forest floor thickness due to consumption by fire. 

Depth of Char Indicators 

1	 Sometimes referred to as "alligatoring", where combustible material appears to have a fissured 

or scaly appearance similar to an alligator's hide. Most commonly associated with finished 

lumber products, such as boards and fence posts. 

Deputy 

1	 A qualified individual who could be delegated the authority to manage a functional operation or 

perform a specific task. In some cases, a Deputy could act as relief for a superior. Deputies can 

be assigned to the incident commander, general staff, and branch directors. 

Desiccant 

1	 Chemical that, when applied to a living plant, causes or accelerates drying of its aerial parts; 

used to facilitate burning of living vegetation by substantially lowering fuel moisture content 

within a few hours. 

Designated Area 

1	 Those areas identified as principal population centers or other areas requiring protection under 

state or federal air quality laws or regulations. 

Designated Dispatch Point (DDP) 

1	 The address where the unit must be physically located, and dispatched from, during the 

mandatory availability period. 

Detection 

1 The act or system of discovering and locating fires. 

synonym: Fire Detection
 

see also: Discovery
 

Detonation 

1	 An extreme rapid decomposition of a material in which the reaction is more than a sonic
 

velocity, for example, high explosives. 

Dew Point 

1	 Temperature to which a specified parcel of air must cool, at constant pressure and water-vapor 

content, in order for saturation to occur. The dew point is always lower than the wet-bulb 

temperature, which is always lower than the dry-bulb temperature, except when the air is 

saturated and all three values are equal. Fog may form when temperature drops to equal the 

dew point. 

Diagram 

1	 A scale drawing showing information about a fire scene. 

Die-Out Pattern Indicators 

1 Fingers or islands of less intensely burned areas or areas where the fire has self extinguished. 

Digital Elevation Model 

1	 A set of points which defines the terrain as numbers for computer applications. This data may 

be used to draw contours, make ortho photos, slope maps, and drive fire models. 

October 2014	 Page 57 
Glossary of Wildland Fire Terminology 

Dilution 

1	 A control strategy used in managing smoke from prescribed fires in which smoke concentration 

is reduced by diluting it through a greater volume of air, either by scheduling during good 

dispersion conditions or burning at a slower rate. 

see also: Dispersion 

Direct Attack 

1 Any treatment applied directly to burning fuel such as wetting, smothering, or chemically 

quenching the fire or by physically separating the burning from unburned fuel. 

synonym: Direct Line
 

Direct Line 

1 Any treatment applied directly to burning fuel such as wetting, smothering, or chemically 

quenching the fire or by physically separating the burning from unburned fuel. 

synonym: Direct Attack
 

Direct Protection Area 

1	 That area for which a particular fire protection organization has the primary responsibility for 

attacking an uncontrolled fire and for directing the suppression action. Such responsibility may 

develop through law, contract, or personal interest of the firefighting agent (e.g., a lumber 

operator). Several agencies or entities may have some basic responsibilities (e.g., private 

owner) without being known as the fire organization having direct protection responsibility. 

synonym: Protection Area 

Directional Vectors 

1	 The physical characteristics of the indicators that show the direction of fire spread, i.e., 

advancing, backing, or lateral. 

Director 

1	 The ICS title for an individual responsible for supervision of a branch. 

Discovery 

1 Determination that a fire exists. Location and reporting of a fire is not required as is with
 

detection. 

see also: Detection
 

Discovery Time 

1	 Elapsed time from start of fire (known or estimated) until the time of the first discovery that 

results directly in fire suppression action. 

Discrete Frequency 

1	 A separate radio frequency most commonly used in air traffic control which reduces frequency 

congestion by controlling the number of aircraft or other resources operating on a particular 

frequency. 

Dispatch 

1	 The implementation of a command decision to move a resource or resources from one place to 

another. 

Dispatch Center 

1	 A facility from which resources are assigned to an incident. 

Dispatcher 

1 A person who receives reports of discovery and status of fires, confirms their locations, takes 

action promptly to provide people and equipment likely to be needed for control efforts. 

see also: Agency Dispatcher 

October 2014	 Page 58 
 

Glossary of Wildland Fire Terminology 

Dispersion 

1 The decrease in concentration of airborne pollutants as they spread throughout an increasing 

volume of atmosphere. 

see also: Dilution 

Display Class 

1	 In WIMS, a one-digit number representing the number of decision points used to evaluate the 

magnitude of the Staffing Index. 

Display Class Breakpoints 

1	 In WIMS, the climatological breakpoints separating the highest staffing levels. Commonly these 

are the index values corresponding to the 90th and 97th or 80th and 95th percentiles for the 

staffing index. 

Display Processor (DPRO) 

1	 The ICS position responsible for displaying incident status information obtained from Field 

Observers, technical specialists, resource status reports, aerial photographs, and infrared data. 

Reports to the Situation Unit Leader. 

see also: Situation Unit 

Distance Learning (DL) 

1	 A concept of providing access to quality wildland fire education and training using appropriate 

instructional technology, delivered anywhere, anytime to prepare a fire management work force 

to safely achieve fire management objectives. 

see also: eLearning 

Distance Measuring Equipment (DME) 

1	 Aircraft navigational equipment that provides the slant range distance in miles (kilometers) from 

the aircraft to the VOR station to which the DME is tuned, usually at or near an airport. 

Distributed Incident Simulation Exercise (DISE) 

1	 An on-line mission rehearsal event providing an individual or team with an experiential learning 

environment utilizing the National Interagency Incident Management System to "game" a 

computer generated incident from multiple training locations. 

see also: Simulation 

Disturbance 

1	 A weather system usually associated with clouds, rain and/or wind. 

Diurnal 

1	 Daily, especially pertaining to cyclic actions which are completed within 24 hours, and which 

recur every 24 hours, such as temperature, relative humidity and wind. 

Divergence 

1	 The expansion or spreading out of a horizontal wind field. Generally associated with high 

pressure and light winds. 

Division 

1	 The ICS organization level between the branch and the task force/strike team. Divisions are 

used to divide an incident into geographical areas of operation. Divisions are established when 

the number of resources exceeds the span-of-control of the operations chief. 

see also: Group 

October 2014	 Page 59 
 

 

Glossary of Wildland Fire Terminology 

Division/Group Supervisor (DIVS) 

1 The ICS position responsible for supervising equipment and personnel assigned to a division or 

group. Reports to a Branch Director or Operations Section Chief. 

see also: Division 

Group 

Documentation Unit 

1	 Functional unit within the planning section responsible for collecting, recording and safeguarding 

all documents relevant to the incident. 

Documentation Unit Leader (DOCL) 

1 The ICS position responsible for supervising the Documentation Unit. Reports to the Planning 

Section Chief. 

see also: Documentation Unit 

Dormant Season Burning 

1	 Prescribed burning early in the dry season before the leaves and undergrowth are completely 

dry or before the leaves are shed, as an insurance against more severe fire damage later on. 

Double Arsonist 

1	 An offender who sets two fires at one site, at the same time, in a single event. 

Double Doughnut 

1 Two lengths of hose rolled side by side or a single length rolled into two small coils for 

convenient handling. 

see also: Doughnut Roll
 

Double Female Coupling 

1	 A hose-coupling device having two female swivel couplings to permit joining two male hose 

nipples of the same size and thread type when lines are laid with couplings in opposite or 

reverse directions. 

Double Jacket Hose 

1	 Fire hose having two cotton or other fiber jackets outside the rubber lining or tubing. 

Double Male Coupling 

1	 A hose-coupling device having two male thread nipples for connecting hose and for connecting 

two female couplings of the same diameter. 

Doughnut Roll 

1	 A 50 or 100-foot length of hose or a 50-foot length of hose rolled up for easy handling. There are 

various ways of forming the doughnut. A convenient one has both couplings close together with 

the male thread protected by the female coupling. 

see also: Double Doughnut 

Downloading 

1	 A calculated reduction in actual payload to provide a margin of safety. 

Dozer 

1 Any tracked vehicle with a front mounted blade used for exposing mineral soil. 

see also: Tractor
 

Dozer Boss (DOZB) 

1	 The individual responsible for supervising the operations of a dozer. 

October 2014	 Page 60 
 

Glossary of Wildland Fire Terminology 

Dozer Company 

1	 A resource that includes a dozer, its transportation unit and a standard complement of 

personnel for its operation.
 

Dozer Line 

1 Fireline constructed by the front blade of a dozer. 

see also: Plow Line
 

Dozer Tender 

1	 Any ground vehicle with personnel capable of maintenance, minor repairs, and limited fueling of 

dozers. 

Draft 

1	 Drawing water from static sources such as a lake, pond, cistern, river, etc. into a pump which is 

above the level of the water supply. This is done by removing the air from the pump and 

allowing atmospheric pressure [14.7 psi (101 kPa) at sea level] to push water through a 

noncollapsible suction hose into the pump. 

Drain Time 

1	 The time (minutes) it takes for foam solution to drop out from the foam mass; for a specified 

percent of the total solution contained in the foam to revert to liquid and drain out of the bubble 

structure. 

Draped Fuels 

1 Needles, leaves, and twigs that have fallen from above and have lodged on lower branches or 

brush. Draped fuels are part of aerial fuels. 

see also: Aerial Fuels 

Drift 

1	 Effect of wind on smoke, retardant drops, paracargo, smokejumper streamers, etc. 

Drift Smoke 

1	 Smoke that has drifted from its point of origin and is no longer dominated by convective motion. 

May give false impression of a fire in the general area where the smoke has drifted. 

Drip Torch 

1	 Hand-held device for igniting fires by dripping flaming liquid fuel on the materials to be burned; 

consists of a fuel fount, burner arm, and igniter. Fuel used is generally a mixture of diesel and 

gasoline. 

see also:	 Backfire Torch
 

Burning Torch
 

Flame Thrower
 

Drive Axle 

1	 An axle that supports a portion of the vehicle weight and transmits a driving force to the wheels. 

Drive Wheels 

1	 Wheels powered by all of the vehicle's drive axles. Dual tires are considered as single wheels. 

The number of wheels is commonly referenced by the terms "4x2", "4x4", etc. where the first 

figure indicates the total number of wheels on the ground and the second figure, the number of 

drive wheels. 

Drizzle 

1	 Precipitation composed exclusively of water drops smaller than 0.02 inches (0.5 mm) in 

diameter. 

October 2014	 Page 61 
 

Glossary of Wildland Fire Terminology 

Drop Configuration 

1 The type of retardant drop selected to cover a ground target. Terms that can specify the type of 

drop configuration include Salvo Drop and Trail Drop. 

see also: Salvo Drop 

Trail Drop 

Drop Pass 

1	 Indicates that the air tanker has the target in sight and will make a retardant drop on this run 

over the target. 

Drop Pattern 

1	 The distribution of an aerially delivered retardant drop on the target area in terms of its length, 

width, and momentum (velocity x mass) as it approaches the ground. The latter determines the 

relative coverage level of the fire retardant on fuels within the pattern. 

synonym: Pattern 

Drop Zone (DZ) 

1 Target area for airtankers, helitankers, cargo dropping. 

see also: Target
 

Drought 

1	 A period of relatively long duration with substantially below-normal precipitation, usually 

occurring over a large area. 

Drought Index 

1 A number representing the net effect of evaporation, transpiration and precipitation in producing 

cumulative moisture depletion in deep duff or upper soil layers. 

see also: Keetch-Byram Drought Index 

Drum Lifter 

1	 Device used to transport a 55-gallon drum (208 L) via sling on a helicopter. 

Dry Adiabatic Lapse Rate 

1	 The rate of decrease of temperature with height of a parcel of dry air lifted adiabatically through 

an atmosphere in hydrostatic equilibrium. Numerically equal to 9.7670 C degrees per km or 

about 5.40 F degrees per thousand feet. 

Dry Air Mass 

1	 A portion of the atmosphere that has a relatively low dew point temperature and where the 

formation of clouds, fog, or precipitation is unlikely. 

Dry Bulb 

1	 A name given to an ordinary thermometer used to determine the temperature of the air (to
 

distinguish it from the wet bulb). 

Dry Bulb Temperature 

1	 The temperature of the air measured in the shade 4-8 feet above the ground. 

Dry Episode (DE) 

1 A contiguous series of days having a pre-established number of fire ignitions with a fuel dryness 

level that historically resulted in a significant fire event for a particular area. 

see also: Fuel Dryness Level 

Significant Fire Event 

Dry Foam 

1	 A low expansion foam type with stable bubble structure and slow drain time which is used
 

primarily for resource and property protection. 

October 2014	 Page 62 
 

 

 

Glossary of Wildland Fire Terminology 

Dry Hydrant 

1	 Permanent devices with fire engine threads attached to expedite drafting operations in locations 

where there are water sources suitable for use in fire suppression (e.g., piers, wharves, bridges 

over streams, highways adjacent to ponds). 

2	 Permanently installed supply private fire pumps which depend upon suction sources. Also 

called suction pipe. 

Dry Lightning Storm 

1	 Thunderstorm in which negligible precipitation reaches the ground. Also called dry storm. 

Dry Run 

1	 A trial pass over the target area by a lead plane and/or an airtanker to pinpoint target areas and 

warn ground personnel of the impending retardant or extinguishing agent drop. 

Dry Storage 

1 Refers to dry chemical retardants stored at air attack bases and available for mixing with water. 

see also: Wet Storage 

Dry-bulb Temperature 

1	 Temperature of the air. 

Dry-bulb Thermometer 

1	 In a psychrometer, the thermometer not covered with muslin which is used to determine air 

temperature. 

Duff 

1 The layer of decomposing organic materials lying below the litter layer of freshly fallen twigs, 

needles, and leaves and immediately above the mineral soil. 

see also: Humus 

Litter 

Durability (Foam) 

1	 The effective life span of foam bubbles. 

Duty Week 

1	 Regular number of hours worked per week by a full-time firefighter, excluding overtime. 

- E -

Economic Fire Protection Theory 

1	 A concept postulating that the object of fire protection is to minimize total cost (i.e., sum of the 

costs of fire prevention, fire presuppression, fire detection, fire suppression, and net costs of fire 

damage/benefits). 

Ecosystem 

1	 An interacting natural system including all the component organisms together with the abiotic 

environment and processes affecting them. 

Ecosystem Sustainability 

1	 The capacity to maintain ecosystem health, productivity, diversity, and overall integrity, for the 

long term, in the context of human activity and use. 

October 2014	 Page 63 
 

 

Glossary of Wildland Fire Terminology 

Eddy 

1	 A circular-like flow of a fluid (such as air or water) drawing its energy from a flow of much larger 

scale, and brought about by pressure irregularities as in the downwind (lee) side of a solid 

obstacle. For example, wind conditions may be erratic and may eddy on the downwind side of 

large rock outcroppings, buildings, etc. 

Edge 

1 The place where plant communities meet or where successional stages or vegetative conditions 

within plant communities come together. 

2 The boundary between two fairly distinct fuel types. 

Edge Firing 

1	 Method of burning in which fires are set along the edges of an area and allowed to spread
 

inward. 

Eductor 

1	 A device used to introduce and mix fire chemical into a water stream. An eductor is a fitting with 

three ports, an inlet for water flow, an outlet for water flow, and an inlet for fire chemical 

concentrate. The flow of water through the eductor produces a region of lower pressure at the 

fire chemical inlet, drawing the chemical into the water stream. 

Effective Windspeed 

1	 The midflame windspeed adjusted for the effect of slope on fire spread. 

Ejector 

1	 A siphon device used to fill an engine's tank when the water source is below or beyond the 

engine's drafting capability. 

Elapsed Time 

1	 The total time taken to complete any step(s) in fire suppression. NOTE: Generally divided 

chronologically into discovery time, report time, getaway time, travel time, attack time, control 

time, mop-up time, and patrol time. 

eLearning 

1	 Conceptually represents the optimum integration of modern educational methods and 

professional staff development training with state of the art technology. The primary goal is 

enhancing on-the-job performance, motivation, and learning performance. 

see also:	 Distance Learning 

Elevation Loss 

1	 In hydraulics, the pressure loss caused by raising water through hose or pipe to a higher 

elevation (roughly equal to one psi for every two-foot increase in elevation above the pump) 

(11.3 kPa per meter). 

Emergency 

1	 Any incident which requires the response of a fire protection organization's attack units and/or 

support units. 

Emergency Firefighter (EFF) 

1	 A person employed as an emergency worker on a forest or wildland fire which threatens 

damage to property under public management. Emergency firefighters are hired for the duration 

of the emergency only. 

see also:	 Administratively Determined
 

Casual
 

October 2014	 Page 64 
 

Glossary of Wildland Fire Terminology 

Emergency Locator Transmitter (ELT) 

1	 A radio transmitter attached to the aircraft structure which operates from its own power source 

on 121.5 MHz and 243 MHz. The transmitter transmits a distinctive downward swept audio tone 

for homing purposes and is designed to function without human action after an accident. 

Emergency Management Coordinator/Director 

1	 The individual within each political subdivision that has coordination responsibility for
 

jurisdictional emergency management. 

Emergency Medical Technician - Basic (EMTB) 

1	 A professional-level provider of emergency medical care who has received training equal to or 

greater than the current DOT emergency medical technician training standards, maintaining 

state or equivalent certification in this classification. 

Emergency Medical Technician - Intermediate (EMTI) 

1	 A professional-level provider of emergency medical care that has been trained to the basic 1999 

EMT level, state certified, and has received additional training to start IVs, use more advanced 

airways, and administer certain medications. 

Emergency Medical Technician - Paramedic (EMTP) 

1	 A professional-level provider of emergency medical care trained above the level of EMTIntermediate to administer drugs, intubate, and other advanced life support procedures in a field 

environment, maintaining state certification in this classification. 

Emergency Operations Center (EOC) 

1	 A pre-designated facility established by an agency or jurisdiction to coordinate the overall
 

agency or jurisdictional response and support to an emergency. 

Emergency Operations Plan 

1	 The plan that each jurisdiction has and maintains for responding to appropriate hazards. 

Emergency Response Provider 

1	 Any federal, state, or local emergency public safety, law enforcement, emergency responder, 

emergency medical (including hospital emergency facilities), and related personnel, agencies, 

and authorities. It is any organization responding to an emergency, or providing mutual aid 

support to such an organization, whether in the field, at the scene of an incident, or operations 

center. 

Emergency Stabilization 

1	 Planned actions to stabilize and prevent unacceptable degradation to natural and cultural 

resource, to minimize threats to life or property resulting from the effects of a fire, or to 

repair/replace/construct physical improvements necessary to prevent degradation of land or 

resources. 

Emergency Worker 

see: Administratively Determined 

Casual 

Emission 

1	 A release of combustion gases and aerosols into the atmosphere. 

Emission Factor (EFp) 

1	 The mass of particulate matter produced per unit mass of fuel consumed (pounds per ton, 

grams per kilogram).
 

October 2014	 Page 65 
 

 

Glossary of Wildland Fire Terminology 

Emission Rate 

1	 The amount, or mass of smoke produced per unit of time. For example: Emission Rate =
 

Available Fuel x Burning Rate x Emission Factor. 

Emission Reduction 

1	 A strategy for controlling smoke from prescribed fires that minimizes the amount of smoke 

output per unit area treated. 

Emission Standard 

1	 A general type of standard that limits the mass of a pollutant that may be emitted by a source. 

The most straightforward emissions standard is a simple limitation on mass of pollutant per unit 

time (e.g., pounds of pollutant per hour). 

Empty Weight 

1	 Weight of an aircraft/engine including the structure, powerplant, all fixed equipment, all fixed 

ballast, unusable fuel, undrainable oil, and total quantity of hydraulic fluid. 

Energy Release Component (ERC) 

1	 The computed total heat release per unit area (British thermal units per square foot) within the 

flaming front at the head of a moving fire. 

Engine 

1	 Any ground vehicle providing specified levels of pumping, water, and hose capacity but with less 

than the specified level of personnel. 

Engine Company 

1	 A resource that includes an engine of a specific type. The type specifies tank capacity, pump 

rating, hose capacity and number of personnel. 

Entrapment 

1	 A situation where personnel are unexpectedly caught in a fire behavior-related, life-threatening 

position where planned escape routes or safety zones are absent, inadequate, or compromised. 

An entrapment may or may not include deployment of a fire shelter for its intended purpose. 

These situations may or may not result in injury. They include "near misses." 

Entrapment Avoidance 

1	 A process used to improve the safety of personnel on the fireline, which emphasizes tools and 

tactics available to prevent being trapped in a burnover situation. This process includes 

appropriate decision making through risk management, application of LCES, use of preestablished trigger points, and recognition of suitable escape routes and safety zones. 

Envelopment 

1	 Direct attack with multiple anchor points, that allows for multiple points of attack. Generally used 

as an engine tactic in the wildland urban interface. 

Environment 

1	 The complex surroundings of an item or area of interest, such as air, water, natural resources, 

and their physical conditions (temperature, humidity). 

Environmental Lapse Rate 

1	 The actual rate of decrease of temperature with elevation. 

Environmental Specialist 

1	 Person responsible to the planning section chief for collecting and analyzing environmental 

information about the incident area, determining environmental restrictions and requirements, 

and providing the information as an input to the incident action and to incident personnel as 

needed. 

October 2014	 Page 66 
 

Glossary of Wildland Fire Terminology 

Episode (Pollution) 

1	 A condition of poor contaminant dispersion which may result in concentrations considered 

potentially harmful to health or welfare. Episodes may also occur during periods of fairly good 

dispersion if the source of air contaminants is extremely large. 

Equilibrium Moisture Content (EMC) 

1	 Moisture content that a fuel particle will attain if exposed for an infinite period in an environment 

of specified constant temperature and humidity. When a fuel particle reaches equilibrium 

moisture content, net exchange of moisture between it and its environment is zero. 

Equipment Manager 

1	 Person responsible to the ground support unit leader for servicing, repairing, and fueling all 

apparatus and equipment on the incident, for obtaining transportation and scheduling its use, 

and for maintaining records of equipment service and use. 

Equipment Time Recorder 

1	 Person responsible to the time unit leader for assisting all other units at the incident in properly 

maintaining a daily record of equipment use time, maintaining current records for charges and 

credits for fuel, parts, services, and commissary items for all equipment, and checking and 

closing all time record forms before demobilization of equipment. 

Equipment Use Fire 

1	 Fire caused by mechanical equipment other than railroad operations. 

Escape Route 

1	 A preplanned and understood route firefighters take to move to a safety zone or other low-risk 

area. When escape routes deviate from a defined physical path, they should be clearly marked 

(flagged). 

Escaped Fire 

1	 Fire which has exceeded or is expected to exceed initial attack capabilities or prescription. 

Escaped Prescribed Fire 

1	 Prescribed fire that has exceeded or is expected to exceed prescription parameters or otherwise 

meets the criteria for conversion to wildfire. A state in which a prescribed fire is no longer doing 

what was expected. 

see also: Escaped Fire 

Estimated Time En Route (ETE) 

1	 Term used in resource planning/following to estimate time spent between points. 

Estimated Time of Arrival (ETA) 

1	 Term used in resource planning/following to estimate time of arrival at a point. 

Estimated Time of Departure (ETD) 

1	 Term used in resource planning/following to estimate time of departure from a point. 

Evacuation 

1	 An organized, phased, and supervised withdrawal, dispersal, or removal of civilians from
 

dangerous or potentially dangerous areas, and their reception and care in safe areas. 

Evaluate 

1	 To review and compare outcomes with management and incident objectives desired for a 

wildland fire. One of the six component activities in an adaptive management process that may 

lead to adjusting future actions. 

October 2014	 Page 67 
 

 

 

Glossary of Wildland Fire Terminology 

Evaluator 

1	 The individual who is qualified in the position being evaluated, or supervises the position being 

evaluated, having responsibility for observing task(s) being performed and documenting 

successful performance for agency certification or re-certification. Evaluator responsibilities 

must remain separate from the individual assigned as Trainer/Coach. 

see also:	 Agency Certification
 

Re-Certification
 

Trainer/Coach
 

Evaporation 

1	 The transformation of a liquid to its gaseous state; heat is released by the liquid during this 

process. 

Event 

1	 A planned, non-emergency activity. ICS can be used as the management system for a wide 

range of events, e.g., parades, concerts or sporting events. 

Exempt / Nonexempt 

1	 Categories of employees as defined in the Fair Labor Standards Act (FLSA), who are either 

covered or exempted from coverage under the ActPay entitlements vary depending on the 

employee's FLSA status. 

Exhaust Primer 

1	 Device which uses the exhaust gas flow of an engine for priming a centrifugal pump. 

Expanded Dispatch 

1	 An organization needed to support an incident which expands along with the Incident Command 

System. 

Expansion 

1	 The ratio of the volume of the foam in its aerated state to the original volume of the non-aerated 

foam solution. 

Expert Witness 

1	 Someone with sufficient skill, knowledge, or experience in a given field so as to be capable of 

drawing inferences or reaching conclusions or opinions that an average person would not be 

competent to reach. The expert's opinion testimony should aim the judge or jury in their 

understanding of the fact at issue. 

Exposure 

1 Property that may be endangered by a fire burning in another structure or by a wildfire. 

2 Direction in which a slope faces, usually with respect to cardinal directions. 

3 The general surroundings of a site with special reference to its openness to winds. 

see also:	 Aspect 

Exposure Fire 

1	 Classification for a fire not originating in a building, but which ignites building(s). A fire 

originating in one building and spreading to another is classified under the original cause of fire. 

Extend 

1	 To drop retardant in such a way that the load slightly overlaps and links a previous drop. 

"Extend your last drop." 

Extended Attack 

1 Actions taken on a wildfire that has exceeded the initial response. 

see also: Extended Attack Incident
 

October 2014	 Page 68 
Glossary of Wildland Fire Terminology 

Extended Attack Incident 

1 An incident that exceeds the capability of the initial attack resources and/or organization to 

successfully manage the incident to conclusion. 

see also: Extended Attack 

Exterior Fire Protection 

1	 The protection of structures from the exterior, with no interior access or activity. 

External Load 

1	 A load that is carried or extends outside of the aircraft fuselage. 

External Payload 

1	 Maximum external stress load (in pounds) with full fuel and pilot in calm air at standard
 

atmospheric temperature. 

Extinguishing Agent 

1	 Substance used to put out a fire by cooling the burning material, blocking the supply of oxygen, 

or chemically inhibiting combustion. 

Extra Burning Period 

1	 For any particular fire which is neither contained nor controlled, any 24-hour period following the 

termination of the first burning period. 

Extreme Fire Behavior 

1	 "Extreme" implies a level of fire behavior characteristics that ordinarily precludes methods of 

direct control action. One or more of the following is usually involved: high rate of spread, prolific 

crowning and/or spotting, presence of fire whirls, strong convection column. Predictability is 

difficult because such fires often exercise some degree of influence on their environment and 

behave erratically, sometimes dangerously. 

see also:	 Blowup
 

Fire Storm
 

Flare-up
 

Eyewitness 

1	 Person who sees evidence of criminal activity, actual commission of a crime or a criminal fleeing 

a crime scene. 

- F -

Facilities Unit 

1	 Functional unit within the logistics section that provides the layout, activation, and management 

of all incident facilities. These facilities may include the incident base, feeding areas, sleeping 

areas, sanitary facilities, etc. 

Facilities Unit Leader (FACL) 

1 The ICS position responsible for supervising the Facilities Unit. Reports to the Service Branch 

Director or Logistics Section Chief. 

see also: Facilities Unit 

Facility Maintenance Specialist 

1	 Person responsible to the base / camp manager for general maintenance of the base or camp, 

including provision of sleeping and sanitation facilities, lighting and electricity, and camp 

cleanliness. 

October 2014	 Page 69 
Glossary of Wildland Fire Terminology 

Fahrenheit 

1	 A temperature scale on which 320 F denotes the temperature of melting ice, and 2120 F the 

temperature of boiling water, both under standard atmospheric pressure. 

Faller 

1	 A person who fells trees. Also called sawyer, and cutter. 

False Alarm 

1	 A reported smoke or fire requiring no suppression; for example, brush burning under control, 

mill smoke, false smoke, etc. 

Federal Aviation Regulation (FAR) 

1	 Refers to the regulations governing all aviation activities of civil aircraft within the United States 

and its territories. 

Federal Fire Policy 

1	 Principles and policies providing a common approach to wildland fire for federal agencies. The 

primary, interagency wildland fire policy document is the "Review and Update of the 

1995 Federal Wildland Fire Management Policy" (January 2001). Implementation of that policy 

is through the "Guidance for Implementation of Federal Wildland Fire Management Policy" 

(February 2009). 

Federal Land Policy and Management Act (FLPMA) 

1	 Federal Land Policy and Management Act of 1976 (Public Law 94-570, 90 Stat. 2743, 43 USC 

1701). 

Female Coupling 

1	 Coupling made to receive a male coupling of the same thread, pitch and/or diameter. 

Field Observer (FOBS) 

1 This ICS position is responsible for collecting and reporting situation information for an incident 

through personal observations and interviews and reports to the Situation Unit Leader. 

see also: Situation Unit 

Field Test 

1	 A job-related test of work capacity designed for those with moderately strenuous duties. This 

test consists a two-mile hike with a 25-pound pack. A time of 30 minutes, the passing score for 

this test, approximates an aerobic fitness score of 40. 

see also: Work Capacity Test 

Fill Tank 

1	 Large, portable tank from which helitankers can hoverfill. 

Filling 

1	 An increase in the central pressure of a low. Counter-clockwise wind flow around the low 

usually decreases as filling occurs. 

Final Approach 

1	 Flight path in the direction of the landing along the extended runway center line from the base 

leg to the runway. 

October 2014	 Page 70 
Glossary of Wildland Fire Terminology 

Final Evaluator 

1	 The individual responsible for completing the position task book's verification statement once all 

tasks in the position task book have been completed and signed off. Only the evaluator on the 

final position performance assignment (the assignment in which all remaining tasks have been 

evaluated and signed off) will complete the verification statement recommending certification. 

see also:	 Position Performance Assignment
 

Position Task Book
 

Final Run 

1	 An air tanker is "on final" when it is on line with the target and intends to make the drop on that 

pass; also applies to cargo dropping. 

Finance/Administration Section 

1	 The section responsible for all administrative and financial considerations on an incident. 

see also:	 Compensation/Claims Unit
 

Cost Unit
 

Procurement Unit
 

Time Unit
 

Finance/Administration Section Chief (FSC1 or FSC2) 

1	 The ICS position responsible for supervising the Finance/Administration Section. Reports to the 

Incident Commander and is a member of the General Staff. This position may have one or more 

deputies assigned. 

see also:	 Finance/Administration Section 

Fine Fuel Moisture 

1	 The probable moisture content of fast-drying fuels which have a timelag constant of 1 hour or 

less; such as, grass, leaves, ferns, tree moss, pine needles, and small twigs (0-1/4"). 

Fine Fuels 

1	 Fast-drying dead or live fuels, generally characterized by a comparatively high surface area-tovolume ratio, which are less than 1/4-inch in diameter and have a timelag of one hour or less. 

These fuels (grass, leaves, needles, etc.) ignite readily and are consumed rapidly by fire when 

dry. 

see also:	 Flash Fuels 

Fingers of a Fire 

1	 The long narrow extensions of a fire projecting from the main body. 

FIRDAT (Fire Data Manipulation Program) 

1 A routine of FIREFAMILY that combines historical weather records with the equations of the 

NFDRS to produce frequency distributions of the NFDRS indexes and components. 

see also: FIREFAMILY (Fire Data Program) 

Fire 

1	 Rapid oxidation, usually with the evolution of heat and light; heat fuel, oxygen and interaction of 

the three. 

Fire Adapted Community (FAC) 

1	 A human community consisting of informed and prepared citizens collaboratively planning and 

taking action to safely co-exist with wildland fire. 

Fire Agency 

1 Official group or organization compelled and authorized under statutes or law to control fires 

within a designated area or upon designated lands. 

see also: Protecting Agency 

Responsible Fire Agency 

October 2014	 Page 71 
 

 

Glossary of Wildland Fire Terminology 

Fire Analysis 

1	 Review of fire management actions taken on a specific fire, group of fires, or fire season in order 

to identify reasons for both effective and ineffective actions, and to recommend or prescribe 

ways and means of doing a more efficient job. Also called hot line review. 

Fire Behavior 

1	 The manner in which a fire reacts to the influences of fuel, weather, and topography. 

Fire Behavior Analyst 

1	 Person responsible to the planning section chief for establishing a weather data collection 

system and for developing fire behavior predictions based on fire history, fuel, weather, and 

topography. 

Fire Behavior Forecast 

1	 Prediction of probable fire behavior, usually prepared by a fire behavior analyst, in support of fire 

suppression or prescribed burning operations. 

Fire Behavior Prediction Model 

1	 A set of mathematical equations that can be used to predict certain aspects of fire behavior 

when provided with an assessment of fuel and environmental conditions. 

Fire Behavior Prediction System 

1	 A system that uses a set of mathematical equations to predict certain aspects of fire behavior in 

wildland fuels when provided with data on fuel and environmental conditions. 

Fire Benefits 

1	 Fire effects with positive monetary, social, or emotional value or that contribute, through 

changes in the resource base, to the attainment of organizational goals. 

Fire Bug 

1	 Arsonist, especially a repetitive firesetter. 

Fire Business 

1	 The characterization of fire occurrence in an area, described in terms of total number of fires 

and acres per year; and number of fires by time, size, cause, fire-day, large fire-day, and 

multiple fire-day. 

Fire Business Thresholds 

1	 Values of one or more fire weather/fire danger indexes that have been statistically related to 

occurrence of fires (fire business). Generally the threshold is a value, or range of values where 

historical fire activity has significantly increased or decreased. 

Fire Cache 

1	 A supply of fire tools and equipment assembled in planned quantities or standard units at a 

strategic point for exclusive use in fire suppression. 

Fire Cause 

1	 Agency or circumstance which started a fire or set the stage for its occurrence; source of a fire’s 

ignition. For statistical purposes fires are grouped into broad cause classes. The nine general 

causes used in the U.S. are lightning, campfire, smoking, debris burning, incendiary, machine 

use (equipment), railroad, children, and miscellaneous. 

Fire Cause Class 

1	 Any class into which wildland fires are grouped according to their origin. 

Fire Climate 

1 Composite pattern of weather elements over time that affect fire behavior in a given region. 

October 2014	 Page 72 
 

 

 

1 

Glossary of Wildland Fire Terminology 

Fire Climax 

Plant community maintained by periodic fires. 

Fire Concentration (Complex) 

1 Generally, a situation in which numerous fires are burning in a locality. 

2 More specifically, the number of fires per unit area or locality for a given period, generally a 

year. 

Fire Crew 

1	 General term for two or more firefighters organized to work as a unit. 

Fire Crew Work Formation 

1	 Standard crew arrangement used for fireline construction in direct or indirect attack; consists of 

line locator, line cutters, rakers, torch operators, and mopup crew. 

Fire Damage 

1	 Detrimental fire effects expressed in monetary or other units, including the unfavorable effects of 

fire-induced changes in the resource base on the attainment of organizational goals. 

Fire Damage Appraisal 

1	 Method of determining financial or other losses resulting from a fire. 

Fire Danger 

1	 Sum of constant danger and variable danger factors affecting the inception, spread, and 

resistance to control, and subsequent fire damage; often expressed as an index. 

Fire Danger Continuum 

1	 The range of possible values for a fire danger index or component, given a set of NFDRS 

parameters and weather input. 

Fire Danger Index 

1	 A relative number indicating the severity of wildland fire danger as determined from burning 

conditions and other variable factors of fire danger. 

Fire Danger Rating 

1	 A fire management system that integrates the effects of selected fire danger factors into one or 

more qualitative or numerical indices of current protection needs. 

Fire Danger Rating Area 

1	 A geographic area of relatively homogenous climate, fuels and topography, tens of thousands of 

acres in size, within which the fire danger can be assumed to be uniform. The basic on-theground unit for which unique fire management decisions are made based on fire danger 

ratings. Weather is represented by one or more NFDRS weather stations. 

Fire Danger Rating Operating Plan 

1	 A guide to collection, communication, and application of fire danger ratings at the local level. 

Fire Danger Rating PocketCard for Firefighter Safety 

1	 A communication aid designed to help firefighters develop an awareness of the local fire 

situation by providing a visual reference to fire danger rating. 

Fire Danger Rating System 

1 The complete program necessary to produce and apply fire danger ratings, including data 

collection, data processing, fire danger modeling, communications, and data storage. 

see also: National Fire Danger Rating System 

October 2014	 Page 73 
 

Glossary of Wildland Fire Terminology 

Fire Day 

1	 Standard 24-hour period beginning at 1000 hours, during which most wildfires undergo a 

predictable speeding up and slowing down of intensity, depending primarily on the influence of 

weather and fuel factors. 

Fire Death 

1	 Fire casualty which is fatal or becomes fatal within one year of the fire. 

Fire Dependent 

1	 Plants and vegetation communities which have evolved adaptations such as a reliance on fire 

as a disturbance agent, protection as a species against the effects of wildland fire, or even a 

strengthening or enhancement by it. 

Fire Detection 

1 Act or system of discovering and locating fires.
 

synonym: Detection
 

Fire Discovery 

1	 The act of determining that a fire exists; does not include determining its location. 

Fire District 

1	 A rural or suburban fire organization, usually tax supported, that maintains fire companies and 

apparatus. It is also called a fire protection district. 

Fire Duty 

1	 Actual physical engagement in firefighting service as distinguished from staff work at 

headquarters or maintenance division; work at an individual fire done by an individual firefighter 

or by a company. 

Fire Ecology 

1	 The study of the effects of fire on living organisms and their environment. 

Fire Edge 

1	 The boundary of a fire at a given moment. 

Fire Education 

1	 Activities to change behaviors and attitudes about fire ecology, wildland fire and the role of fire 

in natural resource management. Defines the purposes for actions that provide information 

about and improve understanding of wildland fire. 

see also: Prevention 

Fire Effects 

1	 The physical, biological, and ecological impacts of fire on the environment. 

Fire Environment 

1	 The surrounding conditions, influences, and modifying forces of topography, fuel, and weather 

that determine fire behavior. 

Fire Frequency 

1	 A general term referring to the recurrence of fire in a given area over time. 

Fire Front 

1	 The part of a fire within which continuous flaming combustion is taking place. Unless otherwise 

specified, the fire front is assumed to be the leading edge of the fire perimeter. In ground fires, 

the fire front may be mainly smoldering combustion. 

October 2014	 Page 74 
 

 

 

 

Glossary of Wildland Fire Terminology 

Fire Guard 

1	 A general term for a firefighter, lookout, patrol, prevention guard, or other person directly 

employed for prevention and/or detection and suppression of fires. 

Fire Hazard 

1	 A fuel complex, defined by volume, type condition, arrangement, and location, that determines 

the degree of ease of ignition and of resistance to control. 

Fire Hazard Index 

1	 A numerical rating for specific fuel types, indicating the relative probability of fires starting and 

spreading, and the probable degree of resistance to control; similar to burning index, but without 

effects of wind speed. 

Fire Hazardous Areas 

1	 Those wildland areas where the combination of vegetation, topography, weather, and the threat 

of fire to life and property create difficult and dangerous problems. 

Fire Information Retrieval and Evaluation System (FIRES) 

1	 A personal computer (PC) program that merges fire and weather/index files, and allows plotting 

and analysis of fire occurrence and fire danger. 

Fire Injury 

1	 Injury suffered as the result of a fire that requires (or should require) treatment by a practitioner 

of medicine within one year of the fire, regardless of whether treatment was actually received. 

Fire Inspector 

1	 Fire prevention specialist or arson investigator. 

Fire Interval 

1	 The number of years between two successive fire events for a given area; also referred to as 

fire-free interval or fire-return interval. 

Fire Investigation 

1	 The process of determining the ignition source, materials first ignited, ignition factors, and party 

responsible for a fire. 

Fire Lane 

1	 Cleared path wide enough to permit single-lane vehicular access in a remote area. 

Fire Load 

1	 The number and size of fires historically experienced on a given unit over a given period 

(usually one day) at a given index of fire danger. 

Fire Load Index (FLI) 

1	 Numerical rating of the maximum effort required to contain all probable fires occurring within a 

rating area during the rating period. 

Fire Management 

1	 All activities for the management of wildland fires to meet land management objectives. Fire 

management includes the entire scope of activities from planning, prevention, fuels or 

vegetation modification, prescribed fire, hazard mitigation, fire response, rehabilitation, 

monitoring and evaluation. 

Fire Management Area 

1	 One or more parcels of land having a common set of fire management objectives. 

October 2014	 Page 75 
 

 

Glossary of Wildland Fire Terminology 

Fire Management Improvements 

1	 All structures built and used primarily for fire management, e.g. lookout towers, lookout cabins, 

telephone lines, and also firebreaks, fuelbreaks, and roads to lookouts. 

Fire Management Objective 

1	 Planned, measurable result desired from fire protection and use based on land management 

goals and objectives. 

Fire Management Plan (FMP) 

1	 A plan that identifies and integrates all wildland fire management and related activities within the 

context of approved land/resource management plans. A fire management plan defines a 

program to manage wildland fires (wildfire and prescribed fire). The plan is supplemented by 

operational plans, including but not limited to preparedness plans, preplanned dispatch plans, 

prescribed fire burn plans, and prevention plans. Fire management plans assure that wildland 

fire management goals and components are coordinated. 

Fire Management Unit (FMU) 

1	 A land area definable by specified management objectives, constraints, topographic features, 

access, values to be protected, political boundaries, fuel types, major fire regime groups, and 

other defined elements that set it apart from an adjacent area. The primary purpose of 

developing Fire Management Units in fire management planning is to assist in organizing 

information in complex landscapes. A fire management unit may have dominant management 

objectives and pre-selected strategies assigned to accomplish these objectives. 

Fire Pack 

1	 A one-person unit of fire tools, equipment, and supplies prepared in advance for carrying on the 

back. 

Fire Perimeter 

1	 The entire outer edge or boundary of a fire. 

Fire Planning 

1	 Systematic technological and administrative management process of designing organization, 

facilities, and procedures, including fire use, to protect wildland from fire. 

Fire Planning Unit (FPU) 

1	 The geographic scope of the landscape defined for the fire management analysis. A Fire 

Planning Unit consists of one or more Fire Management Units. FPUs may relate to a single 

administrative unit, a sub-unit, or any combination of units or sub-units. FPUs are scalable and 

may be contiguous or non-contiguous. FPUs are not predefined by agency administrative unit 

boundaries, and may relate to one or more agencies. They may be described spatially. 

Fire Plotting Map 

1	 A map used for determining the location of fires, commonly provided with an azimuth circle to 

facilitate location by cross bearings. 

Fire Plow 

1	 A heavy duty plowshare or disc plow usually pulled by a tractor to construct a fireline. 

Fire Potential 

1	 The likelihood of a wildland fire event measured in terms of anticipated occurrence of fire(s) and 

management's capability to respond. Fire potential is influenced by a sum of factors that 

includes fuel conditions (fuel dryness and/or other inputs), ignition triggers, significant weather 

triggers, and resource capability. 

see also:	 Ignition Trigger
 

Resource Capability
 

Significant Weather Trigger
 

October 2014	 Page 76 
 

 

Glossary of Wildland Fire Terminology 

Fire Presuppression 

1	 Activities undertaken in advance of fire occurrence to help ensure more effective fire 

suppression. Activities includes overall planning, recruitment and training of fire personnel, 

procurement and maintenance of firefighting equipment and supplies, fuel treatment and 

creating, maintaining, and improving a system of fuelbreaks, roads, water sources, and control 

lines. 

Fire Prevention 

1	 Activities such as public education, community outreach, law enforcement, engineering, and 

reduction of fuel hazards that are intended to reduce the incidence of unwanted human-caused 

wildfires and the risks they pose to life, property or resources. 

Fire Progress Map 

1	 A map maintained on a large fire to show at given times the location of the fire, deployment of 

suppression forces, and progress of suppression. 

Fire Progression 

1	 The progress of the fire outwards from the point of origin. 

Fire Qualifications 

1	 Computerized interagency summary of fire suppression qualifications of listed personnel. 

Available information includes fire training record, fire experience record, and physical fitness 

testing score for each individual. 

Fire Regime 

1	 Description of the patterns of fire occurrences, frequency, size, severity, and sometimes 

vegetation and fire effects as well, in a given area or ecosystem. A fire regime is a 

generalization based on fire histories at individual sites. Fire regimes can often be described as 

cycles because some parts of the histories usually get repeated, and the repetitions can be 

counted and measured, such as fire return interval. 

see also: Fire Regime Groups 

Fire Regime Current Condition Class 

1	 A qualitative measure classified into three classes describing the relative degree of departure 

from historical fire regimes, possibly resulting in alterations of key ecosystem components such 

as species composition, structural stage, stand age, canopy closure, and fuel loadings. 

see also: Condition Class 

Fire Regime Groups 

1	 A classification of fire regimes into a discrete number of categories based on frequency and 

severity. The national, coarse-scale classification of fire regime groups commonly used includes 

five groups: I - frequent (0-35 years), low severity; II - frequent (0-35 years), stand replacement 

severity; III - 35-100+ years, mixed severity; IV - 35-100+ years, stand replacement severity; 

and V - 200+ years, stand replacement severity. 

see also: Fire Regime 

Fire Report 

1	 An official record of a fire, generally including information on cause, location, action taken, 

damage, costs, etc., from start of the fire until completion of suppression action. These reports 

vary in form and detail from agency to agency. 

Fire Resistant Tree 

1 A species with compact, resin-free, thick corky bark and less flammable foliage that has a 

relatively lower probability of being killed or scarred by a fire than a fire sensitive tree. 

see also: Fire Sensitive Tree
 

October 2014	 Page 77 
 

 

 

Glossary of Wildland Fire Terminology 

Fire Resources 

1	 All personnel and equipment available or potentially available for assignment to incidents. 

Fire Retardant 

1	 Any substance except plain water that by chemical or physical action reduces flammability of 

fuels or slows their rate of combustion. 

Fire Return Interval 

see:	 Fire Interval 

Fire Risk 

1 The chance of fire starting, as determined by the presence and activity of causative agents. 

2 A causative agent. 

3 A number related to the potential number of firebrands to which a given area will be exposed 

during the rating day (National Fire Danger Rating System). 

Fire Scar 

1 A healing or healed injury or wound to woody vegetation, caused or accentuated by a fire. 

2 The mark left on a landscape by fire. 

Fire Scar Analysis 

1	 Analysis of one or more fire scars to determine individual tree fire frequency or mean fire 

intervals for specified areas. 

Fire Season 

1 Period(s) of the year during which wildland fires are likely to occur, spread, and affect resources 

values sufficient to warrant organized fire management activities. 

2 A legally enacted time during which burning activities are regulated by federal, state or local 

authority. 

Fire Sensitive Tree 

1 A species with thin bark or highly flammable foliage that has a relatively greater probability of 

being killed or scarred by a fire. 

see also: Fire Resistant Tree 

Fire Service 

1	 The organized fire protection service; its members, individually and collectively; allied 

organizations assisting protection agencies. 

Fire Severity 

1 Degree to which a site has been altered or disrupted by fire; loosely, a product of fire intensity 

and residence time. 

see also: Burn Severity 

Fire Shovel 

1	 Type of shovel specifically designed for use in constructing a fireline; has a tapered blade with 

both edges sharpened for scraping, digging, grubbing, cutting, and throwing. 

Fire Simulator 

1	 Training device that imposes simulated fire and smoke on a landscape image, for the purpose 

of instructing fire suppression personnel in different fire situations and fire suppression 

techniques. 

Fire Spread Model 

1	 A set of physics and empirical equations that form a mathematical representation of the 

behavior of fire in uniform wildland fuels. 

October 2014	 Page 78 
 

 

Glossary of Wildland Fire Terminology 

Fire Storm 

1	 Violent convection caused by a large continuous area of intense fire. Often characterized by 

destructively violent surface indrafts, near and beyond the perimeter, and sometimes by tornadolike whirls. 

see also:	 Blowup
 

Extreme Fire Behavior
 

Flare-up
 

Fire Suppressant 

1	 Any agent used to extinguish the flaming and glowing phases of combustion by direct 

application to the burning fuel.
 

Fire Suppression 

1	 All work and activities connected with control and fire-extinguishing operations, beginning with 

discovery and continuing until the fire is completely extinguished. 

Fire Suppression Organization 

1 The personnel and equipment collectively assigned to the suppression of a specific fire or group 

of fires. 

2 The personnel responsible for fire suppression within a specified area. 

3 The management structure, usually shown in the form of an organization chart of the persons 

and groups having specific responsibilities in fire suppression. 

Fire Swatter 

1 A fire tool that consists of a thick, flat piece of rubber on a long handle used to drag over or 

smother out flames of grass fires. 

see also: Flapper 

Fire Tool Cache 

1	 A supply of fire tools and equipment assembled in planned quantities or standard units at a 

strategic point for exclusive use in wildland operations. 

Fire Trap 

1 An accumulation of highly combustible material, rendering firefighting dangerous. 

2 Any situation in which it is highly dangerous to fight fire. 

Fire Treatment 

1	 The use of fire to accomplish a specified objective. 

Fire Triangle 

1	 Instructional aid in which the sides of a triangle are used to represent the three factors (oxygen, 

heat, fuel) necessary for combustion and flame production; removal of any of the three factors 

causes flame production to cease. 

Fire Type 

1	 A management distinction, made to satisfy legal and budget constraints, based on whether the 

ignition source was planned or unplanned. Under the implementation guidance, only two types 

of wildland fire – wildfire and prescribed fire – are recognized. 

Fire Weather 

1	 Weather conditions which influence fire ignition, behavior, and suppression. 

Fire Weather Forecast 

1 A weather prediction specially prepared for use in wildland fire operations and prescribed fire. 

October 2014	 Page 79 
 

Glossary of Wildland Fire Terminology 

Fire Weather Index (FWI) 

1	 A numerical rating in the Canadian fire danger rating system, based on meteorological 

measurements of fire intensity in a standard fuel type. (The standard fuel type is representative 

of jack pine and lodgepole pine.) The FWI is comprised of three fuel moisture codes, covering 

classes of forest fuel of different drying rates, and two indices that represent rate of spread and 

the amount of available fuel. 

Fire Weather Station 

1	 A meteorological station specially equipped to measure weather elements that have an
 

important effect on fire behavior. 

Fire Weather Watch 

1	 A Fire Weather Watch is issued to advise of conditions which could result in extensive wildland 

fire occurrence or extreme fire behavior, which are expected to develop in the next 12 to 48 

hours, but not more than 72 hours. In cases of dry lightning, a Fire Weather Watch may be 

issued for the next 12 hours. 

see also: Red Flag Warning 

Fire Whirl 

1	 Spinning vortex column of ascending hot air and gases rising from a fire and carrying aloft 

smoke, debris, and flame. Fire whirls range in size from less than one foot to over 500 feet in 

diameter. Large fire whirls have the intensity of a small tornado. 

Firebase 

1	 A computerized program utilized to analyze the fire workload and project the organization to 

adequately manage the workload for a given response area. 

Firebrand 

1	 Any source of heat, natural or human made, capable of igniting wildland fuels. Flaming or 

glowing fuel particles that can be carried naturally by wind, convection currents, or by gravity 

into unburned fuels. 

Firebreak 

1	 A natural or constructed barrier used to stop or check fires that may occur, or to provide a 

control line from which to work.
 

FIRECAST 

1	 Set of computerized FIREMODELS run during fire season at the operations coordination center 

on preselected locations to indicate possible fire spread from those points for that date. 

FireCode 

1	 Unique code (alpha-numeric) assigned to wildland fires. One FireCode project number per fire is 

assigned for use by all five federal wildland firefighting agencies. Fire codes may be any 

combination of four-digit alpha-numeric characters. Each agency's finance community 

incorporates the FireCode project number into the accounting code. 

Fire-Day 

1 In FireFamily Plus, a day with both a weather observation and at least one fire. 

see also: Large Fire-Day
 

Multiple Fire-Day
 

FIREFAMILY (Fire Data Program) 

1	 A computer program that uses historical weather and fire data for fire planning. Its three major 

routines are FIRDAT, SEASON, and FIRINF. 

October 2014	 Page 80 
 

 

Glossary of Wildland Fire Terminology 

FireFamily Plus 

1	 A software application that provides summaries of fire weather/danger climatology and 

occurrence for one or more weather stations extracted from NIFMID. 

Firefighter 

1	 Person whose principal function is fire suppression. 

Firefighting Forces 

1	 Qualified firefighters, together with their equipment and material, used to suppress wildland 

fires. 

Firefighting Technology Implementation Program (FIRETIP) 

1	 A computer program through which the technology of FIRESCOPE is transferred to areas 

outside southern California, where complex, multi-agency fires and other incidents commonly 

occur. 

Firefinder Map 

1 A map, generally mounted on a wood or metal base, that is provided with an azimuth circle at 

the center of which is pivoted an alidade, and forms part of an Osborne Firefinder. 

see also: Osborne Firefinder 

Fire-flood Cycle 

1	 The greatly increased rate of water run off and soil movement from steep slopes that may follow 

removal of the vegetative cover by burning. 

Fireground 

1	 Operational area on which firefighters combat a fire. 

Firelamp (Fire and Land Management Planning) 

1	 Computerized multi-resource model that simulates the effects that naturally caused prescribed 

fires have on the future production of natural resources such as timber, forage, wildlife, 

recreation, and water. 

Fireline 

1	 The part of a containment or control line that is scraped or dug to mineral soil. 

Fireline Explosives (FLE) 

1	 Specially developed coils containing explosive powder that are detonated to create a fireline 

through ground fuels. 

Fireline Intensity 

1	 The product of the available heat of combustion per unit of ground and the rate of spread of the 

fire, interpreted as the heat released per unit of time for each unit length of fire edge. The 

primary unit is Btu per second per foot (Btu/sec/ft) of fire front. 

2	 The rate of heat release per unit time per unit length of fire front. Numerically, it is the product of 

the heat yield, the quantity of fuel consumed in the fire front, and the rate of spread. 

FIREMODEL 

1	 Computer program which with specified information (fuel, weather, topography) predicts an 

hourly rate of spread from a point of origin. 

Fire-proofing 

1	 Removal or treatment of fuels to reduce the danger of fires igniting or spreading. (E.g., fireproofing roadsides, campsites, structural timber.) Protection is relative, not absolute. 

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Glossary of Wildland Fire Terminology 

FIRESCOPE 

1	 Firefighting Resources of California Organized for Potential Emergencies. A multi-agency 

coordination system designed to improve the capabilities of California's wildland fire protection 

agencies. Its purpose is to provide more efficient resources allocation and utilization, particularly 

in multiple or large fire situations during critical burning conditions. 

Firesetter 

1	 Person who starts a fire, usually deliberately and maliciously. 

Firesetting 

1	 Starting a fire, usually deliberately and maliciously. 

Firing Out 

1	 The act of setting fire to unburned fuels located between the control line and main fire in burning 

out operations. 

Firing Technique 

1 Any method or pattern of igniting a wildland area to consume the fuel in a prescribed pattern. 

E.g., heading or backing fire, spot fire, strip-head fire, and ring fire. 

see also: Ignition Pattern 

First Order Fire Effects (FOFE) 

1	 The effects that concern the direct or immediate consequences of fire, such as biomass 

consumption, crown scorch, bole damage, and smoke production. First order effects form an 

important basis for predicting secondary effects such as tree regeneration, plant succession, 

and changes in site productivity, but these involve interaction with many other non-fire variables. 

see also: Second Order Fire Effects 

First-in 

1	 Firefighters initially attacking a fire, usually the first to arrive at the fire scene. 

Fix 

1 Geographical position determined by visual reference to the surface, by reference to one or 

more radio navigational aids, by celestial plotting, or by any other navigational device. 

Fixed Tank 

1	 A device mounted inside or directly underneath an aircraft which can contain water or retardant 

for dropping onto a fire. 

Fixed-point Detection 

1	 Detection of fires from lookout towers or other semi-permanent locations as distinguished from 

roving ground patrols or aerial detection. 

Flame 

1 A mass of gas undergoing rapid combustion, generally accompanied by evolution of sensible 

heat and incandescence. 

2 Light given off by burning gasses during the combustion process. 

Flame Angle 

1	 Angle between the flame at the leading edge of the fire front and the ground surface, expressed 

in degrees. 

Flame Depth 

1	 The depth of the fire front. 

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Glossary of Wildland Fire Terminology 

Flame Height 

1	 The average maximum vertical extension of flames at the leading edge of the fire front. 

Occasional flashes that rise above the general level of flames are not considered. This distance 

is less than the flame length if flames are tilted due to wind or slope. 

Flame Length 

1	 The distance between the flame tip and the midpoint of the flame depth at the base of the flame 

(generally the ground surface), an indicator of fire intensity. 

Flame Thrower 

1 Device for throwing a stream of flaming liquid, used to facilitate rapid ignition during burn out 

operations on a wildfire or during a prescribed fire operation. 

synonym: Terra Torch ® 

see also:	 Backfire Torch
 

Burning Torch
 

Drip Torch
 

Flaming Combustion Phase 

1	 Luminous oxidation of gases evolved from the rapid decomposition of fuel. This phase follows 

the pre-ignition phase and precedes the smoldering combustion phase, which has a much 

slower combustion rate. Water vapor, soot, and tar comprise the visible smoke. Relatively 

efficient combustion produces minimal soot and tar, resulting in white smoke; high moisture 

content also produces white smoke. 

Flaming Front 

1	 That zone of a moving fire where the combustion is primarily flaming. Behind this flaming zone 

combustion is primarily glowing or involves the burning out of larger fuels (greater than about 3 

inches in diameter). Light fuels typically have a shallow flaming front, whereas heavy fuels have 

a deeper front. 

see also:	 Fire Front 

Flaming Phase 

1	 That phase of a fire where the fuel is ignited and consumed by flaming combustion. 

Flammability 

1	 The relative ease with which fuels ignite and burn regardless of the quantity of the fuels. 

Preferred to "inflammability."
 

Flammable 

1 Easily ignitable and capable of burning and producing flames. 

see also: Nonflammable
 

Flammable liquid 

1	 A liquid generally with a flash point below 140F (60C) and a vapor pressure that does not 

exceed 40 PSI at 100F (37.8C). 

Flank Fire 

1 A firing technique consisting of treating an area with lines of fire set into the wind which burn 

outward at right angles to the wind. 

synonym: Lateral Fire 

Flanking Action 

see:	 Flanking Fire Suppression 

Flanking Fire Suppression 

1	 Attacking a fire by working along the flanks either simultaneously or successively from a less 

active or anchor point and endeavoring to connect two lines at the head. 

October 2014	 Page 83 
 

Glossary of Wildland Fire Terminology 

Flanks of a Fire 

1	 The parts of a fire's perimeter that are roughly parallel to the main direction of spread. 

Flapper 

1	 Fire suppression tool, sometimes improvised, used in direct attack for smothering out flames 

along a fire edge; may consist merely of a green pine bough or wet sacking, or be a 

manufactured tool such as a flap of belting fabric fastened to a long handle. 

see also:	 Fire Swatter 

Flare-up 

1	 Any sudden acceleration in rate of spread or intensification of the fire. Unlike blowup, a flare-up 

is of relatively short duration and does not radically change existing control plans. 

see also:	 Blowup
 

Extreme Fire Behavior
 

Fire Storm
 

Flash Fuels 

1 Highly combustible fine fuels such as grass, leaves, draped pine needles, fern, tree moss and 

some kinds of slash, which ignite readily and are consumed rapidly when dry. 

see also: Fine Fuels 

Flash Point 

1	 Lowest temperature at which the vapor of a combustible liquid can be made to ignite in air. 

Flashover 

1	 Rapid combustion and/or explosion of unburned gases trapped at some distance from the main 

fire front. Usually occurs only in poorly ventilated topography. 

2	 Stage of a fire at which all surfaces and objects within a space have been heated to their ignition 

temperature, and flame breaks out almost at once over the surface of all objects within the 

space. 

Flight Following 

1	 The method and process through which an aircraft is tracked from departure point to 

destination. Flight following is the knowledge of the aircraft location and condition at regular 

intervals with a reasonable degree of certainty such that, in the event of mishap, those on board 

may be rescued. 

Flight Path 

1 Track of an aircraft over the earth's surface. 

2 Specified information relating to the intended flight of an aircraft that is filed orally or in writing 

with an air traffic control facility. 

Flight Time 

1	 The time from the moment the aircraft first moves under its own power for the purpose of flight 

until the moment it comes to rest at the next point of landing. 

Flight Visibility 

1	 Average forward horizontal distance from the cockpit of an aircraft in flight at which prominent 

unlighted objects may be seen and identified by day and prominent lighted objects may be seen 

and identified by night. 

Floatable Pump 

1	 Small portable pump that floats in the water source. 

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Glossary of Wildland Fire Terminology 

Flow Conditioner 

1	 Chemical powders that will, in very small quantities, tend to prevent other powders from caking 

and flocculating. Imparts free-flowing qualities to powder. Used with fire retardant chemicals. 

Fluid Foam 

1	 A low expansion foam type with some bubble structure and moderate drain time, exhibiting 

properties of both wet and dry foam types, which is used for extinguishment, protection, and 

mopup. 

Fly Ash 

1	 Particulate matter emitted by a fire and larger than 10 microns in diameter with a consequently 

short residence time in the atmosphere. 

Foam 

1	 The aerated solution created by forcing air into, or entraining air in water containing a foam 

concentrate by means of suitably designed equipment or by cascading it through the air at a 

high velocity. Foam reduces combustion by cooling, moistening and excluding oxygen. 

Foam Blanket 

1	 A layer of foam which forms an insulating and reflective barrier to heat and is used for fuel 

protection, suppression, and mopup. 

Foam Concentrate 

1	 The concentrated foaming agent as received from the manufacturer which, when added to 

water, creates a foam solution; use only those approved for use in wildland fire situations by the 

authority having jurisdiction. 

Foam Generation 

1	 The foam production process of forcing air into or entraining air in foam solution, creating a 

mass of bubbles. 

Foam Line 

1	 A body of foam placed along areas to be protected from fire; also used as an anchor for indirect 

attack in place of hand-made fire line. 

Foam Solution 

1	 A low expansion foam type with no expansion, therefore lacking bubble structure, which is used 

for mopup and flame knockdown. 

Foam Systems 

1	 The apparatus and techniques used to mix concentrate with water to make solution, pump and 

mix air and solution to make foam, and transport and apply foam. (Systems defined here 

include compressed air foam and nozzle aspirated.) 

Foam Type 

1	 A term used to describe the consistency and viscosity of low expansion foam as the
 

combination of drain time and expansion. 

Foaming Agent 

1	 An additive that reduces the surface tension of water (producing wet water) causing it to spread 

and penetrate more effectively and which produces foam through mechanical means. 

October 2014	 Page 85 
 

 

 

 

Glossary of Wildland Fire Terminology 

Foehn Wind 

1	 A warm, dry and strong general wind that flows down into the valleys when stable, high pressure 

air is forced across and then down the lee slopes of a mountain range. The descending air is 

warmed and dried due to adiabatic compression producing critical fire weather conditions. 

Locally called by various names such as Santa Ana winds, Devil winds, North winds, Mono 

winds, etc. 

Folding Tank 

1	 A portable, collapsible water tank with a tubular frame. Tank capacities vary in size from 500­

1500 gallons. 

Foliage Freeze Indicators 

1	 Small branches, needles, and leaves on green vegetation that take on a windswept appearance 

and "freeze" in that position. 

Food Unit 

1	 Functional unit within the Logistics Section responsible for providing meals for incident 

personnel.
 

Food Unit Leader (FDUL) 

1 The ICS position responsible for supervising the Food Unit. Reports to the Service Branch 

Director or Logistics Section Chief. 

see also: Food Unit
 

Forb 

1	 A plant with an herbaceous (soft, rather than permanent woody) stem, that is not a grass or 

grasslike plant. 

Forced Landing 

1	 Landing necessitated by failure of engines, systems, or components which makes continued 

flight impossible and which may not result in damage. 

Forcible Entry 

1	 Entering a structure of vehicle illegally by means or physical force, often characterized by prying 

doors and breaking windows. 

Forecast Area 

1	 Geographical area for which a fire weather forecast is specified. 

Forest Fire 

1	 Variously defined for legal purposes (e.g., the State of California Public Resources Code: 

uncontrolled fire on lands covered wholly or in part by timber, brush, grass, grain, or other 

flammable vegetation). Types of fires are ground, surface, and crown. 

Forest Planning Language and Simulator (FORPLAN) 

1	 Computer program developed to facilitate the use of simulation for integrating many different 

resource management activities, including fire, into the land management planning process. 

FORPLAN incorporates unique characteristics of previous systems, links numerous models and 

data bases, allows selection of variable resolution levels, and permits discrete time simulation of 

disturbances on plants, fuels, and animals. 

Forest Protection 

1	 Forestry branch concerned with prevention and damage control to forests from human actions 

(unauthorized fire, grazing, felling, smoke), pests and pathogens, and damage from storm, frost, 

and other climatic agents. 

October 2014	 Page 86 
 

 

Glossary of Wildland Fire Terminology 

Forest Residue 

1	 Accumulation in the forest of living or dead (mostly woody) material that is added to and 

rearranged by human activities such as harvest, cultural operations, and land clearing. 

Forest Service 

1	 Generally understood to mean an agency of the U.S. Department of Agriculture. However, 

some states also use Forest Service, e.g., Colorado State Forest Service. 

Forestry Weather Information System (FWIS) 

1	 A real time system which takes observations and forecasts supplied by NWS in coded numeric 

form, reformats that input by computer based algorithms, and distributes the reformatted 

information as numeric and worded diagnoses and forecasts for specialized users in localized 

areas. 

Forward Looking Infrared (FLIR) 

1	 Hand held or aircraft mounted device designed to detect heat differentials and display their 

images on a video screen. FLIRs have thermal resolution similar to IR line scanners, but their 

spatial resolution is substantially less; commonly used to detect hot spots and flareups obscured 

by smoke, evaluate the effectiveness of firing operations, or detect areas needing mopup. 

Forward Rate of Spread 

1	 The speed with which a fire moves in a horizontal direction across the landscape, usually 

expressed in chains per hour or feet per minute. 

Fragile Fire Cause Objects 

1	 Objects that are easily susceptible to damage from head and flame and can be easily damaged 

or destroyed by suppression action and/or during the evidence collection process. E.g., 

cigarette ash. 

Free Burning 

1	 The condition of a fire or part of a fire that has not been slowed by natural barriers or by control 

measures. 

Free Drop 

1	 Cargo, not attached to a parachute, that is dropped intentionally from an aircraft in flight. 

Free Flow (Hydraulics) 

1	 Maximum water flow rate a fire pump will attain when there are no restrictions at the pump outlet 

or losses due to friction or head. 

Freezing Rain 

1	 Rain that freezes upon contact with objects on the ground. 

Frequency of Occurrence 

1	 A quantitative expression of the presence or absence of individuals of a species in a population; 

the ratio between the number of sample units that contain a species and the total number of 

sample units. 

Friction Layer 

1	 The layer of the atmosphere in which the frictional force of the earth’s surface exercises an 

appreciable influence on winds. 

Friction Loss 

1	 Pressure loss caused by the movement of water or solution against the interior surface of fire 

hose, pipe, or fittings; normally measured in pressure loss per length of hose or pipe. 

October 2014	 Page 87 
 

 

Glossary of Wildland Fire Terminology 

Friction Reducing Agent (FRA) 

1	 Water soluble substance that reduces frictional drag of solutions and dampens turbulent flow 

while being pumped through pipe or hose. 

Front 

1	 In meteorology, the boundary between two air masses of differing atmospheric properties. 

Frost 

1	 Crystals of ice formed and deposited like dew, but at a temperature below freezing. 

Frozen 

1 In the 1978 version of NFDRS, the herbaceous stage when cold temperatures kill herbaceous 

plants and force woody fuels into dormancy. 

Fuel 

1 Any combustible material, especially petroleum-based products and wildland fuels. 

Fuel Arrangement 

1	 A general term referring to the spatial distribution and orientation of fuel particles or pieces. 

Fuel Bed 

1	 An array of fuels usually constructed with specific loading, depth, and particle size to meet 

experimental requirements; also, commonly used to describe the fuel composition. 

Fuel Bed Depth 

1	 Average height of surface fuels contained in the combustion zone of a spreading fire front. 

Fuel Characteristics 

1	 Factors that make up fuels such as compactness, loading, horizontal continuity, vertical 

arrangement, chemical content, size and shape, and moisture content. 

Fuel Class 

1	 Part of the National Fire Danger Rating System (NFDRS). Group of fuels possessing common 

characteristics. Dead fuels are grouped according to 1-, 10-, 100-, and 1000-hour timelag, and 

living fuels are grouped as herbaceous (annual or perennial) or woody. 

Fuel Condition 

1	 Relative flammability of fuel as determined by fuel type and environmental conditions. 

Fuel Continuity 

1	 The degree or extent of continuous or uninterrupted distribution of fuel particles in a fuel bed 

thus affecting a fire's ability to sustain combustion and spread. This applies to aerial fuels as 

well as surface fuels. 

Fuel Depth 

1 The average distance from the bottom of the litter layer to the top of the layer of fuel, usually the 

surface fuel. 

see also: Fuel Bed Depth 

Fuel Dryness Level (DL) 

1	 A quantitative measure of fuel moisture and receptability to ignition as determined by an 

accepted Fire Danger Rating System index that influences fire growth, intensity, or activity. 

Fuel Group 

1	 An identifiable association of fuel elements of distinctive species, form, size, arrangement, or 

other characteristics. General fuel groups are grass, brush, timber, and slash. 

October 2014	 Page 88 
Glossary of Wildland Fire Terminology 

Fuel Loading 

1	 The amount of fuel present expressed quantitatively in terms of weight of fuel per unit area. 

This may be available fuel (consumable fuel) or total fuel and is usually dry weight. 

Fuel Management 

1	 Act or practice of controlling flammability and reducing resistance to control of wildland fuels 

through mechanical, chemical, biological, or manual means, or by fire, in support of land 

management objectives. 

Fuel Model 

1	 Simulated fuel complex for which all fuel descriptors required for the solution of a mathematical 

rate of spread model have been specified. 

Fuel Modification 

1 Manipulation or removal of fuels to reduce the likelihood of ignition and/or to lessen potential 

damage and resistance to control (e.g., lopping, chipping, crushing, piling and burning). 

synonym: Fuel Treatment 

Fuel Moisture Analog 

1	 Device that emulates the moisture response of specific classes of dead fuels, constructed from 

organic or inorganic materials (e.g., half-inch ponderosa pine dowels representing ten-hour 

timelag fuels). 

Fuel Moisture Content 

1	 The quantity of moisture in fuel expressed as a percentage of the weight when thoroughly dried 

at 212 degrees F. 

Fuel Moisture Indicator Stick 

1	 A specially prepared stick or set of sticks of known dry weight continuously exposed to the 

weather and periodically weighed to determine changes in moisture content as an indication of 

moisture changes in wildland fuels. 

Fuel Reduction 

1	 Manipulation, including combustion, or removal of fuels to reduce the likelihood of ignition and/or 

to lessen potential damage and resistance to control. 

Fuel Size Class 

1	 A category used to describe the diameter of down dead woody fuels. Fuels within the same 

size class are assumed to have similar wetting and drying properties, and to preheat and ignite 

at similar rates during the combustion process. 

Fuel Temperature 

1	 The temperature reading measured from a fuel stick fully exposed to sunlight, above a 

representative fuel bed, using one of two methods (within a 3/4-inch or across a 1/2-inch pine 

dowel). 

Fuel Tender 

1	 Any vehicle capable of supplying engine fuel to ground or airborne equipment. 

Fuel Treatment 

1 Manipulation or removal of fuels to reduce the likelihood of ignition and/or to lessen potential 

damage and resistance to control (e.g., lopping, chipping, crushing, piling and burning). 

synonym: Fuel Modification 

October 2014	 Page 89 
Glossary of Wildland Fire Terminology 

Fuel Type 

1	 An identifiable association of fuel elements of distinctive species, form, size, arrangement, or 

other characteristics that will cause a predictable rate of spread or resistance to control under 

specified weather conditions. 

Fuelbreak 

1	 A natural or manmade change in fuel characteristics which affects fire behavior so that fires 

burning into them can be more readily controlled. 

Fuelbreak System 

1	 A series of modified strips or blocks tied together to form continuous strategically located fuel 

breaks around land units. 

Fuels Wet Flag 

1	 A one-character code indicating whether or not fine fuels are wet or dry. 

Fugitive Color 

1	 A coloring agent used in fire retardants that is designed to fade rapidly following retardant 

application in order to minimize the visual impacts of the retardant. 

Full-thickness Burn 

1	 A burn involving all the layer of the skin. Muscle layers below the skin and bones may also be 

damaged. Muscle layers below the skin and bones may also be damaged. Areas of the skin 

may be charred black or areas that are dry and white. (also called Third Degree Burn) 

see also:	 Partial-thickness Burn
 

Superficial Burn
 

Fume 

1	 An airborne irritating, noxious, or toxic smoke, vapor, or any combination of these produced by a 

volatile substance or a chemical reaction. 

Function 

1	 In ICS, function refers to the five major activities, command, operations, planning, logistics and 

finance/administration. 

Fusee 

1	 A colored flare designed as a railway warning device, widely used to ignite backfires and other 

prescribed fires. 

- G -

Gallons per Minute (GPM) 

1	 The measure of water flow in firefighting. It is used to measure the output of wildland and 

structural fire engines, pumps, hose streams, nozzles, hydrants, and water mains. 

Gap 

1	 Weak or missed area in a retardant drop or in a fireline. 

Gate Valve 

1	 A valve with a gate-like disk that moves up and down at right angles to the flow when actuated 

by a stem screw and hand wheel. Gate valves are best for service that requires infrequent valve 

operation and where the disk is kept either fully open or closed. 

October 2014	 Page 90 
Glossary of Wildland Fire Terminology 

Gear Pump 

1	 Positive displacement pump which uses closely meshed gears to propel water when high 

pressures and low volumes are desired; can be used safely only with clear water-- suspended 

particles of soil or rocks can quickly wear the gears and reduce pressure and volume of water. 

General Fire Weather Forecast 

1	 A forecast, issued daily during the regular fire season to resource management agencies, that is 

intended for planning of daily fire management activities, including daily staffing levels, 

prevention programs, and initial attack on wildfires. Also called presuppression forecast. 

see also:	 Incident Weather Forecast
 

Spot Weather Forecast
 

General Origin Area 

1	 The larger area where the fire started that is readily identifiable based on macro scale indicators 

and witness statements. 

General Services Administration (GSA) 

1	 An agency of the United States Government that includes the Federal Supply Service, the
 

Automated Data and Telecommunications Service, the Public Buildings Service, and the
 

National Archives and Records Service. 

General Staff 

1	 The group of incident management personnel reporting to the Incident Commander. They may 

each have a deputy, as needed. The General Staff consists of: Operations Section Chief, 

Planning Section Chief, Logistics Section Chief, and Finance/Administration Section Chief. 

General Winds 

1 Large scale winds caused by high- and low-pressure systems but generally influenced and 

modified in the lower atmosphere by terrain. 

see also: Local Winds 

Slope Winds 

Geographic Area 

1	 A boundary designated by governmental agencies (wildland fire protection agencies) within 

which they work together for the interagency, intergovernmental planning, coordination, and 

operations leadership for the effective utilization of emergency management resources within 

their area. There are nine geographic areas. A listing of the areas can be found in the National 

Interagency Mobilization Guide, Chapter 20, section 21.1 along with listings of the Geographic 

Coordinating Areas and Geographic Area Coordination Centers. 

see also:	 Geographic Area Coordination Center
 

Geographic Coordinating Area
 

Geographic Area Coordinating Group (GACG) 

1	 An interagency body of fire management representatives from each federal and state land 

management agency within a nationally recognized regional area that provides leadership and 

support to facilitate safe and efficient fire management activities. Working collaboratively, a 

GACG's mission is not only for wildland fire emergencies, but for other emergency incidents, as 

necessary. 

October 2014	 Page 91 
Glossary of Wildland Fire Terminology 

Geographic Area Coordination Center (GACC) 

1	 The physical location of an interagency, regional operation center for the effective coordination, 

mobilization and demobilization of emergency management resources. A coordination center 

serves federal, state and local wildland fire agencies through logistical coordination of resources 

throughout the geographic area, and with other geographic areas, as well. Listings of 

geographic coordination centers and their respective geographic coordinating areas can be 

found within the National Interagency Mobilization Guide. 

see also:	 Geographic Area
 

Geographic Coordinating Area
 

Geographic Coordinating Area 

1	 A boundary designated by governmental agencies (wildland fire protection agencies), that may 

coincide with a geographic area boundary or may be a subdivision of a geographic area within 

which they work together coordinating, for the effective, mobilization and demobilization of 

emergency management resources within their area. Listings of geographic coordinating areas 

and geographic coordination centers can be found in the National Interagency Mobilization 

Guide, Chapter 20, Section 21.1. 

see also:	 Geographic Area
 

Geographic Area Coordination Center
 

Geographic Information System Specialist (GISS) 

1	 The incident support position responsible for collecting and maintaining geospatial data and 

providing geospatial analysis and producing products (maps, etc.) in support of wildland fire 

incident planning. GISS is utilized in support of incident management, assigned to an ICS 

organization's Situation Unit. 

Geostationary Operational Environmental Satellite (GOES) 

1 The satellite used for data relay from NFDRS weather stations to ASCADS. 

see also: National Fire Danger Rating System
 

Getaway Time 

1	 Elapsed time from receipt of notification by the personnel charged with initiating suppression 

action to the departure of the first attack unit. 

Global Positioning System (GPS) 

1	 A system of navigational satellites operated by the U.S. Department of Defense and available 

for civilian use. The system can track objects anywhere in the world with an accuracy of 

approximately 40 feet. 

Glowing Combustion 

1	 the process of oxidation of solid fuel accompanied by incandescence. All volatiles have already 

been driven off, oxygen reaches the combustion surfaces, and there is no visible smoke. This 

phase follows the smoldering combustion phase and continues until the temperature drops 

below the combustion threshold value, or until only non-combustible ash remains. 

Glowing Combustion Phase 

1 The final phase of combustion following flaming and smoldering phases. 

see also: Glowing Combustion
 

Going Fire 

1	 Any wildfire on which suppression action has not reached an extensive mop up stage. 

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Glossary of Wildland Fire Terminology 

Gradient Wind 

1	 Wind flowing parallel to pressure isobars or contours with low pressure on the left of the 

observer in the Northern Hemisphere; velocity such that the pressure gradient, Coriolis, and 

centrifugal force acting in the area are in balance. 

2	 Wind created by differing barometric pressures between high- and low-pressure systems. 

Velocity is generally five to 30 miles per hour, and wind shifts are usually gradual as systems 

move and shift. 

Grass Fire 

1	 Any fire in which the predominant fuel is grass or grasslike. 

Grass Stem Indicators 

1 Remains of grass stems having different appearances based on the direction of fire spread. 

Grass Type 

1	 In NFDRS, the two grass types (annual, perennial) determine how seasonal drying of live 

herbaceous fuels is modeled. 

Gravimetric 

1	 Of, or pertaining to, measurement by weight. 

Gravity Tank 

1	 Water storage tank for fire protection and sometimes community water service that supplies 

water by gravity pressure. 

Greenbelt 

1 Landscaped and regularly maintained fuelbreak, usually put to some additional use (e.g., golf 

course, park, playground). 

see also: Fuelbreak 

Greenhouse Effect 

1	 the heating of the earth's surface by both atmospheric infrared radiation and incoming solar 

radiation. 

Greenness Factor 

1 In the 1988 version of NFDRS, a code scaled from 0 to 20 representing the greenness of 

grasses and shrubs from near dead to maximum greenness. 

see also: Relative Greenness 

Green-up 

1	 Green-up for the 1978 version of NFDRS model is defined as the beginning of a new cycle of 

plant growth. Green-up usually occurs once a year, except in desert areas where rainy periods 

can produce a flush of new growth more than once a year. Green-up may be signaled at 

different dates for different fuel models. Green-up should not be started when the first flush of 

green occurs in the area. Instead, the vegetation that will be the fire problem (represented by 

the NFDRS fuel model associated with the weather station) when it matures and cures should 

be identified. Green-up should start when the majority of this vegetation starts to grow. 

Grid Ignition Technique 

1	 Method of igniting prescribed fires in which ignition points are set individually at predetermined 

spacing with predetermined timing throughout the area to be burned. Also called point source 

ignition technique. 

Gridding 

1	 To search for a small fire by systematically traveling over an area on parallel courses or
 

gridlines. 

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Glossary of Wildland Fire Terminology 

Gross Axle Weight Rating (GAWR) 

1	 The value specified by the manufacturer as the maximum allowable weight placed on an axle of 

a vehicle when fully equipped, including payload, fluids and occupants. 

Gross Vehicle Weight (GVW) 

1	 Actual vehicle weight, including chassis, body, cab, equipment, water, fuel, crew, and all other 

load. 

Gross Vehicle Weight Rating (GVWR) 

1	 The value specified by the manufacturer as the maximum allowable weight of a vehicle fully 

equipped, including payload, fluids and occupants. 

Gross Weight 

1	 Total allowable weight of a loaded aircraft for takeoff or landing, adjusted for altitude
 

differences. 

Ground Effect 

1	 Reaction of a rotor downdraft against the ground surface, forming a "ground cushion" that 

increases lifting capability of that section of air. 

Ground Fire 

1 Fire that consumes the organic material beneath the surface litter ground, such as a peat fire. 

Ground Fog 

1	 Fog which extends vertically to less than 20 feet. 

Ground Fuel 

1	 All combustible materials below the surface litter, including duff, tree or shrub roots, punky
 

wood, peat, and sawdust, that normally support a glowing combustion without flame. 

Ground Speed 

1	 Speed with which an aircraft traverses the ground over which it flies. 

Ground Support Unit 

1	 Functional unit within the Logistics Section responsible for the fueling, maintaining and repairing 

of vehicles, and the transportation of personnel and supplies. 

Ground Support Unit Leader (GSUL) 

1 The ICS position responsible for supervising the Ground Support Unit. Reports to the Support 

Branch Director or Logistics Section Chief. 

see also: Ground Support Unit 

Ground Truth 

1	 Verification at the site of what has been observed and/or measured from aircraft, satellites, other 

aerial platforms, aerial photographs, or maps. 

Ground Visibility 

1	 Horizontal visibility observed at the ground. 

Group 

1	 Groups are established to divide the incident into functional areas of operation. Groups are 

composed of resources assembled to perform a special function not necessarily within a single 

geographic division. Groups, when activated, are located between branches and resources in 

the operations section. 

see also: Division 

October 2014	 Page 94 
Glossary of Wildland Fire Terminology 

Growing Season Burning 

1	 Prescribed burning or use of wildland fire during the photosynthetically-active growing season, 

where live fuel moistures are relatively high and the dominant vegetation, grasses, forbs, and 

herbaceous vegetation are fully greened. 

Guard Unit 

1	 Geographic subdivision of a fire-protected area, delimiting the initial attack bounds of a single 

fire guard or fire crew. 

Gum Thickened Sulphate (GTS) 

1	 A dry chemical product which is mixed with water to form a fire retardant slurry. 

Gust 

1	 Rapid fluctuations in wind speed with a variation of 10 knots (11.5 mph) or more between peaks 

and lulls. 

- H -

Haines Index 

1	 An atmospheric index used to indicate the potential for wildfire growth by measuring the stability 

and dryness of the air over a fire. 

Hand Crew 

1	 A number of individuals that have been organized and trained and are supervised principally for 

operational assignments on an incident. 

Handline 

1	 Fireline constructed with hand tools. 

Hangup (Tree Falling) 

1	 A situation in which a tree is lodged in another, preventing it from falling to the ground. 

Hard Suction Hose 

1	 Noncollapsible suction hose attached to a pump and used to draft water from a source lower 

than the pump. Customary hose sizes in wildland fire engines are 2 and 2-1/2 inches in 

diameter (51 and 64 mm). 

Hazard 

1	 Any real or potential condition that can cause injury, illness or death of personnel, or damage to, 

or loss of equipment or property. 

Hazard Assessment 

1 Assess hazards to determine risks. Assess the impact of each hazard in terms of potential loss, 

cost, or strategic degradation based on probability and severity. 

see also: Hazard Fuel 

Risk 

Hazard Fuel 

1	 A fuel complex defined by kind, arrangement, volume, condition, and location that presents a 

threat of ignition and resistance to control. 

Hazard Map 

1	 Map of the area of operations that shows all of the known aerial hazards, including but not 

limited to power lines, military training areas, hang gliding areas, etc. 

October 2014	 Page 95 
 

 

 

Glossary of Wildland Fire Terminology 

Hazard Pay 

1	 A salary differential that compensates employees for exposure to hazards in the course of their 

duties. 

Hazard Reduction 

1	 Any treatment of living and dead fuels that reduces the potential spread or consequences of 

fire. 

Hazardous Areas 

1	 Those wildland areas where the combination of vegetation, topography, weather, and the threat 

of fire to life and property create difficult and dangerous problems. 

Hazardous Materials 

1 Substances that are identified, classified, and regulated in the Code of Federal Regulations, 

Title 49 and Hazardous Materials Regulations 175. 

2 A substance or material which has been determined by the Secretary of Transportation to be 

capable of posing an unreasonable risk to health, safety, and property when transported in 

commerce and which has been so designated. 

Haze 

1 A sufficient concentration of atmospheric aerosols to affect a visible attenuation of light and 

measurable reduction in visual range. The aerosol particle diameter is near the wavelength of 

visible light, optimizing the light scattering efficiency of the particles. 

Haze Meter 

1	 Instrument for measuring the dependable range of distance at which a standard smoke column 

can be detected by the unaided eye under existing haze conditions. 

Head Fire 

1 A fire spreading or set to spread with the wind. 

synonym: Advancing Fire 

Head of a Fire 

1	 The most rapidly spreading portion of a fire's perimeter, usually to the leeward or up slope. 

Head Pressure 

1	 Pressure due to elevation of water. Equals 0.433 pounds per square inch (PSI) per foot of 

elevation. (Approximately 0.5 PSI is required to lift water 1 foot in elevation) 

Heading 

1	 The compass direction in which the longitudinal axis of the aircraft points. 

Headlamp 

1	 Flashlight, ordinarily worn by firefighter on the front of the helmet. 

Heat 

1	 Temperatures higher than that of the normal atmosphere, produced by the process of burning or 

oxidation. 

Heat Content 

1	 The net amount of heat that would be given off if fuel burns when it is absolutely dry, noted as 

Btu per pound of fuel. 

October 2014	 Page 96 
 

 

Glossary of Wildland Fire Terminology 

Heat Low 

1	 An area of low pressure caused by intense heating of the earth's surface. High surface 

temperature causes air to expand and rise, resulting in low atmospheric pressure and induces a 

weak inflow of air at the surface. Air which rises in a heat low is very dry so clouds seldom form. 

Rising air above a heat low produces a warm upper level high and results in a net outflow of air 

aloft. Heat lows remain practically stationary over areas which produce them. 

Heat of Combustion 

1	 The heat energy resulting from the complete combustion of a fuel, expressed as the quantity of 

heat per unit weight of fuel. The high heat of combustion is the potential available, and the low 

heat of combustion is the high heat of combustion minus several losses that occur in an open 

system (primarily heat of vaporization of moisture in the fuel) . 

Heat per Unit Area 

1	 Total amount of heat released per unit area as the flaming front of the fire passes, expressed as 

Btu/square foot; a measure of the total amount of heat released in flames. 

Heat Probe 

1	 Apparatus used to detect heat. 

Heat Release Rate 

1 Total amount of heat produced per unit mass of fuel consumed per unit time. 

2 Amount of heat released to the atmosphere from the convective-lift fire phase of a fire per unit 

time. 

Heat Transfer 

1	 Process by which heat is imparted from one body to another, through conduction, convection, 

and radiation. 

Heat Trough 

1	 A Heat Low which is elongated in shape. Also called: Heat Low; Thermal Low; Thermal Trough. 

Heat Value 

1	 The total heat energy released during combustion, usually published as units of heat energy 

produced per unit mass of ovendry fuel consumed. 

Heat Yield 

1	 The heat of combustion corrected for various heat losses, mainly the presence of moisture in 

the fuel. To a very close approximation, the quantity of heat per pound of fuel burned that 

passes through a cross section of the convection column above a fire that is burning in a 

neutrally stable atmosphere. Also called low heat of combustion. 

Heavy Equipment Transport 

1	 Any ground vehicle capable of transporting a dozer, tractor, or other heavy piece of equipment. 

Also called lowboy. 

Heavy Fuels 

1	 Fuels of large diameter such as snags, logs, large limbwood, which ignite and are consumed 

more slowly than flash fuels. Also called coarse fuels. 

Heavy Ignition Source 

1	 Objects that will tend to settle or burrow under the surface of the materials first ignited as a 

result of either weight or temperature. I.e., welding slag, exhaust particles, large metal 

fragments, etc. 

Height 

1	 The vertical measurement of vegetation from the top of the crown to ground level. 

October 2014	 Page 97 
 

 

Glossary of Wildland Fire Terminology 

Held Line 

1	 All control line that still contains the fire when mopup is completed. Excludes lost line, natural 

barriers not backfired, and unused secondary lines. 

Helibase 

1	 The main location within the general incident area for parking, fueling, maintenance, and loading 

of helicopters. It is usually located at or near the incident base. 

Helibase Crew 

1	 A crew of individuals who may be assigned to support helicopter operations. 

Helibase Manager (HEB1 or HEB2) 

1	 This ICS position is responsible for controlling helicopter take-offs and landings at a helibase, 

managing helibase assigned helicopters, supplies, fire retardant mixing and loading and reports 

to the Air Support Group Supervisor. 

Helibase Radio Operator (HERO) 

1	 This ICS position is responsible for maintaining radio communications between incident 

assigned helicopters and helibases, and Takeoff and Landing Coordinator and reports to the 

Helibase Manager. 

Helibucket 

1	 Specially designed bucket carried by a helicopter like a sling load and used for aerial delivery of 

water or fire retardants. 

Helicopter 

1 An aircraft that depends principally on the lift generated by one or more rotors for its support in 

flight. 

synonym: Rotorcraft 

Helicopter Boss (HELB) 

1	 An individual assigned to an agency helicopter to supervise assigned crew members, oversee 

the loading and unloading of personnel and/or cargo, and ensure that agency policies and 

procedures governing helicopter operations are followed. 

Helicopter Coordinator (HLCO) 

1	 this ICS position is responsible for coordinating tactical and logistical helicopter missions at the 

incident and reports to the Air Tactical Group Supervisor. This position can be airborne or 

ground-based with one or more assigned to an incident, depending on the number and type of 

missions to be accomplished. 

Helicopter Crewmember (HECM) 

1	 An individual assigned to an agency or call-when-needed helicopter to support helicopter
 

operations. 

Helicopter Manager (HCWN) 

1 An individual assigned to a call-when-needed (CWN) helicopter to serve as helicopter boss, 

administer contracts, and verify CWN helicopter and pilot qualifications. 

see also: Helicopter Boss 

Helicopter Tender 

1	 A ground service vehicle capable of supplying fuel and support equipment to helicopters. 

Helicopter Timekeeper 

1	 This ICS position is responsible for keeping time for helicopters assigned to the helibases and 

reports to the Helibase Radio Operator. 

October 2014	 Page 98 
 

 

 

Glossary of Wildland Fire Terminology 

Heliport 

1	 A permanent facility for the operation of helicopters which has been built to FAA standards and 

which is marked on aeronautical charts. Natural resource agencies refer to agency heliports as 

permanent helibases. 

Helipumper 

1	 Lightweight portable pump developed for transport by helicopter. 

Helispot 

1	 A natural or improved takeoff and landing area intended for temporary or occasional helicopter 

use. 

Helispot Manager (HESM) 

1	 This ICS position is responsible for controlling helicopter take-offs and landings at a helispot, 

managing helispot assigned helicopters, supplies, fire retardant mixing and loading and reports 

to the Helibase Manager. 

Helitack 

1	 The utilization of helicopters to transport crews, equipment, and fire retardants or suppressants 

to the fireline during the initial stages of a fire. The term also refers to the crew that performs 

helicopter management and attack activities. 

Helitack Crew 

1	 A crew of firefighters specially trained and certified in the tactical and logistical use of helicopters 

for fire suppression. 

Helitack Foreman 

1	 A supervisory firefighter trained in the tactical use of helicopters for fire suppression. 

Helitank 

1	 Specially designed tank, generally of fabric or metal, fitted closely to the bottom of a helicopter 

and used for transporting and dropping suppressants or fire retardants. 

Helitanker 

1	 A helicopter equipped with a fixed tank, Air Tanker Board certified, capable of delivering a 

minimum of 1,100 gallons of water, foam, or retardant. 

Helitorch 

1	 An aerial ignition device hung from or mounted on a helicopter to disperse ignited lumps of 

gelled gasoline. Used for backfires, burnouts, or prescribed burns. 

see also:	 Aerial Ignition Device
 

Delayed Aerial Ignition Devices
 

Ping-Pong Ball System
 

Plastic Sphere Dispenser
 

Herb 

1	 A plant that does not develop woody, persistent tissue but is relatively soft or succulent and 

sprouts from the base (perennials) or develops from seed (annuals) each year. Includes 

grasses, forbs and ferns. 

Herbaceous Fuel Moisture 

1	 In NFDRS, a calculated value representing the approximate moisture content of the live 

herbaceous vegetation in the rating area expressed as a percentage of the oven dry weight of 

the sample. 

see also:	 Woody Fuel Moisture 

October 2014	 Page 99 
 

Glossary of Wildland Fire Terminology 

Herbaceous Stage 

1	 The modeled condition of herbaceous vegetation (pre-green, green-up, transition, cured, frozen) 

for the 1978 version of NFDRS. 

Hidden Fire Scar 

1	 Fire scar in a tree resulting from fire injury to the cambium without destruction of the overlying 

bark and therefore not readily discernible. 

Higbee Cut 

1	 Removal of the first (i.e., outside) thread of a female or male coupling to prevent crossing or 

mutilation of threads. Dimpled rocker lug on female coupling indicates beginning of Higbee Cut. 

High Expansion 

1	 Foam with an expansion between 201:1 and 1000:1. 

High Fire Risk Day 

1	 A day when an ignition trigger and/or significant weather trigger and an appropriate fuel dryness 

level combine to create conditions that historically have resulted in a significant fire event for a 

particular area. 

see also:	 Fuel Dryness Level
 

Ignition Trigger
 

Significant Fire Event
 

Significant Weather Trigger
 

High Pressure Fog 

1	 Small capacity spray jet produced at very high pressures (greater than 250 psi, the normal 

maximum pressure for standard ground tankers) and discharged through a small hose with a 

gun-type nozzle. 

Historical Weather Station 

1	 In WIMS, a weather station that is no longer in service for which access to archived
 

observations is still available in NIFMID. 

Holding Actions 

1	 All actions taken to stop the spread of fire. 

Holding Forces 

see:	 Holding Resources 

Holding Orbit 

1	 A predetermined maneuver which keeps an aircraft within a specified airspace while awaiting 

further orders. 

Holding Resources 

1	 Resources assigned to do all required fire suppression work following fireline construction but 

generally not including extensive mop up. 

Holdover Fire 

1	 A fire that remains dormant for a considerable time. Also called sleeper fire. 

Home Assessment 

1	 Evaluation of a dwelling and its immediate surrounding to determine its potential to escape 

damage by an approaching wildland fire. Includes the fuels and vegetation in the yard and 

adjacent to the structure, roof environment, decking and siding materials, prevailing winds, 

topography, fire history, etc., with the intent of mitigating fire hazards and risks. 

October 2014	 Page 100 
 

 

Glossary of Wildland Fire Terminology 

Home Unit 

1 The designated agency or entity providing contracted resources that employs the individual who 

is actively pursuing a position performance assignment (completion of a position task book). 

see also: Position Performance Assignment 

Position Task Book 

Hose Clamp 

1	 Crimping device for stopping the flow of water in a hose. 

Hose Lay 

1	 Arrangement of connected lengths of fire hose and accessories on the ground, beginning at the 

first pumping unit and ending at the point of water delivery. 

Hose Rack 

1	 Item for storing drying fire hose. 

Hose Reel 

1 A rotating drum used for winding booster hose (normally) for storing and dispensing. 

see also: Booster Reel
 

Hose Thread 

1	 The specific dimensions of screw thread employed to coupled fire hose and equipment. 

American National Standards (NH) have been adopted for fire hose couplings threads in 3/4, 1­

1/2, 2-1/2, 3-1/2, 4, 5, and 6-inch sizes. 

Hose Washer 

1	 Device for cleaning the exterior of fire hose. 

Hoseline Tee 

1	 A fitting that may be installed between lengths of hose to provide an independently controlled 

outlet for a branch line. 

Hot Spot 

1	 A particularly active part of a fire. 

Hotshot Crew 

1	 Intensively trained fire crew used primarily in hand line construction (Type-1). 

Hot-spotting 

1	 Checking the spread of fire at points of more rapid spread or special threat. Is usually the initial 

step in prompt control, with emphasis on first priorities. 

Hover 

1	 A stationary in-flight condition for helicopters when no directional flight is achieved. 

Hover Ceiling 

1	 Highest altitude above sea level at which a helicopter can hover at maximum computed gross 

weight. It is generally specified whether the quoted hover ceiling refers to hovering in ground 

effect (HIGE) or hovering out of ground effect (HOGE). 

Hover Hook-up 

1	 Attaching of a cargo lead line to a hovering helicopter. 

Hoverfill 

1 The process by which a helicopter fills a helibucket while hovering above the water source. 

October 2014	 Page 101 
 

Glossary of Wildland Fire Terminology 

Hovering in Ground Effect (HIGE) 

1	 The situation in which a helicopter is hovering sufficiently close to the ground to achieve added 

lift due to the effects of "ground cushion." The HIGE ceiling, for a given gross weight, thus is 

greater than the HOGE (Hovering Out of Ground Effect) ceiling. 

Human Resource Specialist (HRSP) 

1	 An individual having responsibility for assisting incident personnel and agency administrators 

with human resource, civil rights, and inappropriate behavior concerns. HRSP solicits 

involvement from the appropriate incident authorities in order to resolve human resource, civil 

rights, and inappropriate behavior issues informally, quickly, legally, and at the lowest impacted 

level. 

Human-caused Fire 

1	 Any fire caused directly or indirectly by person(s). 

Human-caused Risk 

1	 Part of the National Fire Danger Rating System (NFDRS). A model for predicting the average 

number of reportable human caused fires from a given ignition component value. 

Human-caused Risk Scaling Factor 

1	 Part of the National Fire Danger Rating System (NFDRS). Number relating human-caused fire 

incidence to the ignition component in a fire danger rating area. It is based on three to five years 

of fire occurrence and fire weather data that adjusts the prediction of the basic human-caused 

fire occurrence model to fit local experience. 

Humidity 

1 General term referring to the moisture content of the atmosphere. 

see also: Relative Humidity
 

Humus 

1	 Layer of decomposed organic matter on the forest floor beneath the fermentation layer and 

directly above the soil. It is that part of the duff in which decomposition has rendered vegetation 

unrecognizable and mixing of soil and organic matter is underway. 

see also:	 Duff
 

Litter
 

Hydrophobicity 

1	 Resistance to wetting exhibited by some soils, also called water repellency. The phenomenon 

may occur naturally or may be fire-induced. It may be determined by water drop penetration 

time, equilibrium liquid-contact angles, solid-air surface tension indices, or the characterization 

of dynamic wetting angles during infiltration. 

Hygrothermograph 

1	 Recording instrument combining, on one paper record, the variation of dry-bulb temperature and 

relative humidity as a function of time. 

- I -

Identification Run 

1	 Dry run over the target area by the leadplane to indicate an airtanker's flight path and target, 

while the air tanker pilot is observing. 

Igniter 

1 A pyrotechnic device specifically designed to initiate burning of a fuel mixture or propellant. 

October 2014	 Page 102 
 

Glossary of Wildland Fire Terminology 

Ignition Component 

1	 Part of the National Fire Danger Rating System (NFDRS). A rating of the probability that a 

firebrand will cause an actionable fire. 

Ignition Energy 

1 Quantity of heat or electrical energy that must be absorbed by a substance to ignite and burn. 

Ignition Factor 

1	 The conditions, subsequent actions, and sequence of events that bring a competent ignition 

source into contact with the materials first ignited. Also referred to as the cause of the fire. 

Ignition Method 

1	 The means by which a fire is ignited, such as hand-held drip torch, helitorch, and backpack 

propane tanks. 

Ignition Pattern 

1	 Manner in which a prescribed fire is ignited. The distance between ignition lines or points and 

the sequence of igniting them is determined by weather, fuel, topography, firing technique, and 

other factors which influence fire behavior and fire effects. 

Ignition Probability 

1	 Chance that a firebrand will cause an ignition when it lands on receptive fuels. (Syn. IGNITION 

INDEX) 

Ignition Source 

1 Any process or event capable of causing a fire. 

see also: Fire Cause
 

Ignition Method
 

Ignition Time 

1	 Time between application of an ignition source and self-sustained combustion of a fuel. 

Ignition Trigger 

1	 A causative agent for wildland fire. For example, human or lightning.) 

IMI Interactivity Levels 

1	 Standards to which IMI products are developed conforming to interactivity level(s) which are 

appropriate for the instructional design, strategy, media, content, and course specifications. 

see also:	 IMI Level 1 Interactivity
 

IMI Level 2 Interactivity
 

IMI Level 3 Interactivity
 

Interactive Multimedia Instruction
 

IMI Level 1 Interactivity 

1	 This is the lowest level of courseware development. It is normally a knowledge familiarity lesson, 

provided in a linear format (one idea after another). Use Level 1 to introduce an idea or concept, 

or to familiarize. Provide minimal interactivity by using selectable screen icons that are inserted 

into the linear, or almost linear, flow of the courseware. Allow the student little or no control of 

the sequence of instructional media presented, including: simple developed graphics, clip art, 

customer provided video and audio segments (clips). Make use of typical input/output 

peripherals throughout the lesson. 

see also:	 Interactive Multimedia Instruction 

October 2014	 Page 103 
 

Glossary of Wildland Fire Terminology 

IMI Level 2 Interactivity 

1 This involves the recall of more information than a level 1 and allows the student more control 

over the lesson’s scenario through screen icons and other peripherals, such as light pens or 

touch screens. Typically level 2 is used for non-complex operations and maintenance lessons. 

Simple emulations or simulations are presented to the user. As an example, the user is 

requested to rotate switches, turn dials, make adjustments, or identify and replace a faulted 

component as part of a procedure. This also may include simple to standard developed 

graphics, and/or clip art, and video and audio clips. 

see also: Interactive Multimedia Instruction 

IMI Level 3 Interactivity 

1	 This involves the recall of more complex information (compared to levels 1 and 2) and allows 

the user an increased level of control over the lesson scenario through peripherals such as light 

pen, touch screen, track ball, or mouse. Video, graphics, or a combination of both is presented 

simulating the operation of a system, subsystem, or equipment to the user. The lesson scenario 

training material typically is complex and involves more frequent use of peripherals to affect a 

transfer of learning. Operation and maintenance procedures are normally practiced with level 3 

scenarios and students may be required to alternate between multiple screens to keep pace 

with the lesson material. Multiple software branches (two to three levels) and rapid response are 

provided to support remediation. Emulations and simulations are an integral part of this 

presentation. This may also include complex developed graphics, and/or clip art, and video and 

audio clips. 

see also: Interactive Multimedia Instruction 

Impeller 

1	 Rotating part of a centrifugal pump which imparts energy to the liquid to be moved. For
 

shearing purposes, the impeller is on a rotating shaft within the body of liquid. 

Implementation Plan 

1	 The design and definition of all the activities, resources, limitations, and contingencies required 

for successful wildland fire management. 

Impulse 

1	 A term used in weather primarily to describe a weak disturbance that does not necessarily have 

an associated storm center or surface low. The disturbance usually does not create severe 

weather and is frequently associated with a marine air push. 

Incendiary 

1	 A burning compound or metal used to produce intense heat or flame, like a bomb. 

Incendiary Device 

1	 Contrivance designed and used to start a fire. 

Incendiary Fire 

1	 A fire that is deliberately ignited under circumstances in which the person knows that the fire 

should not be ignited. An incendiary fire is not necessarily a fire that meets the legal definition of 

an arson fire. 

Incident 

1	 An occurrence either human-caused or natural phenomenon, that requires action or support by 

emergency service personnel to prevent or minimize loss of life or damage to property and/or 

natural resources. 

October 2014	 Page 104 
 

 

Glossary of Wildland Fire Terminology 

Incident Action Plan (IAP) 

1	 Contains objectives reflecting the overall incident strategy and specific tactical actions and 

supporting information for the next operational period. The plan may be oral or written. When 

written, the plan may have a number of attachments, including: incident objectives, organization 

assignment list, division assignment, incident radio communication plan, medical plan, traffic 

plan, safety plan, and incident map. Formerly called shift plan. 

see also: Action Plan 

Incident Base 

1	 Location at the incident where the primary logistics functions are coordinated and administered. 

(Incident name or other designator will be added to the term Base.) The incident command post 

may be collocated with the base. There is only one Base per incident. 

Incident Business Advisor (IBA) 

1	 Liaison and advisor to the Agency Administrator or Area Commander and works directly for the 

Agency Administrator or Area Commander. Serves as a bridge to the Agency Administrator, 

Incident Management Team, and other incident support functions. 

Incident Command Post (ICP) 

1	 Location at which primary command functions are executed. The ICP may be collocated with 

the incident base or other incident facilities. 

Incident Command System (ICS) 

1	 A standardized on-scene emergency management concept specifically designed to allow its 

user(s) to adopt an integrated organizational structure equal to the complexity and demands of 

single or multiple incidents, without being hindered by jurisdictional boundaries. 

Incident Commander (ICT1, ICT2, ICT3, ICT4, or ICT5) 

1	 This ICS position is responsible for overall management of the incident and reports to the 

Agency Administrator for the agency having incident jurisdiction. This position may have one or 

more deputies assigned from the same agency or from an assisting agency(s). 

Incident Communications Center 

1	 The location of the communications unit and the message center. 

Incident Communications Manager (INCM) 

1	 This ICS position is responsible for providing incident dispatch services and for receiving and 

transmitting radio and telephone messages to and among incident assigned personnel and 

reports to the Communications Unit Leader. 

see also: Communications Unit 

Incident Communications Technician (COMT) 

1	 This ICS position is responsible for the programming, tracking, installation, and maintenance of 

radio and telephone electronic communication equipment and system design for an incident, 

and reports to the Communications Unit Leader. 

see also: Communications Unit 

Incident Management Team 

1	 The incident commander and appropriate general and command staff personnel assigned to an 

incident. 

Incident Medical Specialist Assistant (IMSA) 

1	 This individual assists the IMS manager in managing the IMS program and provides direct 

emergency medical and occupational health care to incident personnel according to the 

protocols of their IMS program. Frequently, this person may manage a remote camp medical 

unit. 

October 2014	 Page 105 
 

Glossary of Wildland Fire Terminology 

Incident Medical Specialist Manager (IMSM) 

1	 This individual manages the IMS program on the incident and works for the medical unit leader 

(MEDL) if one is present. The IMS may also be a MEDL. This person must have successfully 

completed IMS assignments as an ISMT and IMSA, and the IMS training within their home 

region. 

Incident Medical Specialist Program 

1	 An incident-based program to care for emergent and minor medical as well as common 

occupational health care problems of incident personnel. This program may be deployed to 

Type I and Type II incidents. Currently, this program is only available in three regions: Northwest 

(R6), Northern Rockies (R1) and Alaska (R10). In Alaska, the program is known as the 

Firemedic. 

Incident Medical Specialist Technician (IMST) 

1	 This individual provides direct emergency medical and occupational health care to incident 

personnel according to the protocols of their IMS program and works under the supervision of 

the IMS manager or IMS assistant. 

Incident Meteorologist (IMET) 

1	 A specially trained meteorologist who provides site specific weather forecasts and information at 

an incident. The individual works under the direction of the fire behavior analyst and the 

planning section chief. 

see also:	 All Hazards Meteorological Response System
 

Micro-Remote Environmental Monitoring System
 

Incident Objectives 

1	 Statements of guidance and direction necessary for the selection of appropriate strategy(s), and 

the tactical direction of resources. Incident objectives are based upon agency administrators 

direction and constraints. Incident objectives must be achievable and measurable, yet flexible 

enough to allow for strategic and tactical alternatives. 

Incident Organization 

1	 Resources, together with a complement of overhead personnel, calculated to be sufficient to 

provide fire efficient incident management. 

Incident Overhead 

1	 All supervisory positions described in the Incident Command System. 

Incident Qualifications Card 

1	 A card issued to persons showing their incident management and trainee qualifications to fill 

specified fire management positions in an incident management organization. 

Incident Support Organization 

1	 Includes any off-incident support provided to an incident. Examples would be agency dispatch 

centers, airports, mobilization centers, etc. 

Incident Weather Forecast 

1 A special weather forecast for a specific incident prepared by a meteorologist on site at or near 

the incident area. 

see also: General Fire Weather Forecast 

Spot Weather Forecast 

October 2014	 Page 106 
 

 

Glossary of Wildland Fire Terminology 

Incident with Potential 

1	 Wildland fire-related mishap that results in serious or non-serious injuries involving multiple 

personnel, near accident (which would have resulted in a serious injury or fatality), or substantial 

loss of property (less than $250,000). The mishap may be so complex and fraught with 

operational discrepancies that it has the potential to produce an accident, serious injury, or 

fatality given a similar environment or set of circumstances that existed at the time of the 

incident. 

see also: Near Miss 

Increaser 

1	 Increasing coupling used on hose, pump, or nozzles to permit connection of a larger size of 

hose. 

Increment 

1	 Any resource or grouping of resources on which individual status is maintained. 

Incremental Drop 

1	 Air tanker drop in which tank doors are opened in sequence so that fire retardant cascades 

somewhat continuously. 

Independent Action 

1	 Fire suppression activities by other than regular fire suppression organizations or a fire
 

cooperator. 

Independent Crown Fire 

1	 A fire that advances in the tree crowns alone, not requiring any energy from the surface fire to 

sustain combustion or movement. Also called running crown fire. 

Indicated Airspeed (IAS) 

1	 The speed of an aircraft as shown on its pitot static airspeed indicator. Calibrated to reflect 

standard atmosphere adiabatic compressible flow at sea level, uncorrected for airspeed system 

errors. 

Indicator 

1	 Visual remains at a fire scene revealing the fire’s progress and action. 

Indicator Categories 

1	 Classification of indicators into a variety of categories based on how they are formed and the 

types of material they are found on. 

Indirect Attack 

1	 A method of suppression in which the control line is located some considerable distance away 

from the fire's active edge. Generally done in the case of a fast-spreading or high-intensity fire 

and to utilize natural or constructed firebreaks or fuelbreaks and favorable breaks in the 

topography. The intervening fuel is usually backfired; but occasionally the main fire is allowed to 

burn to the line, depending on conditions. 

Indirectly Visible Area 

1	 Ground, or the vegetation growing thereon, that is not directly visible to a fixed point lookout but 

lies at not more than a specified depth (commonly 300 feet, 91 meters) below the lookout's line 

of sight. 

Inductor 

1	 A control mechanism that allows a regulated quantity of foam concentrate to be introduced into 

the main hose line. 

October 2014	 Page 107 
 

 

Glossary of Wildland Fire Terminology 

Industrial Fire Precaution Level (IFPL) 

1	 An application of fire danger rating to support regulation of contractors involved in land 

management activities for fire prevention purposes in the Pacific Northwest. 

Industry Crew 

1	 Fire crew composed of mill, forestry, or construction workers. 

Infrared (IR) 

1 A heat detection system used for fire detection, mapping, and hotspot identification. 

see also: Thermal Imagery
 

Infrared Groundlink (IR) 

1	 A capability through the use of a special mobile ground station to receive air-to-ground IR 

imagery at an incident. 

Inhibition 

1	 Process of extinguishing fire by the use of an agent that interrupts the chemical reactions in the 

combustion process. 

Inhibitor 

1	 Any agent which retards a chemical reaction. 

Initial Attack (IA) 

1	 A preplanned response to a wildfire given the wildfire’s potential. Initial attack may include size 

up, patrolling, monitoring, holding action or suppression. 

Initial Attack Crew 

1	 Specially trained and equipped fire crew for initial attack on a fire. 

Initial Attack Fire (IAF) 

1	 Fire that is generally contained by the attack units first dispatched, without a significant 

augmentation of reinforcements, within two hours after initial attack, and full control is expected 

within the first burning period. 

Initial Attack Incident Commander (IAIC) 

1	 The incident commander at the time the first attack forces commence suppression work on a 

fire. 

Initial Response 

1	 The initial decisions and actions taken in reaction to a reported incident. 

Inmate Crew 

1	 Any fire crew composed of prison inmates or wards. 

Inside Diameter (ID) 

1	 The internal diameter of a tube, conductor, or coupling, as distinguished from its OD (Outside 

Diameter). Fire hose sizes are classified by a nominal internal diameter. 

In-stand Wind 

1	 Wind speed within a stand at about eye level. 

Instrument Flight Rules Conditions (IFR) 

1	 Weather conditions below the minimum for flight under Visual Flight Rules and therefore 

requiring the observance of instruments inside the aircraft for controlling flight; generally 

considered to be less than 1000' AGL and 3 miles distant.
 

see also: Visual Flight Rules Conditions 

October 2014	 Page 108 
 

Glossary of Wildland Fire Terminology 

Instrument Landing System (ILS) 

1	 System for airplane landing in which the pilot is guided by radio beams. 

Instrument Shelter 

1	 Naturally or artificially ventilated structure, constructed to specifications and used to shield 

weather measuring instruments from direct sunshine and precipitation. 

Interactive Multimedia Instruction (IMI) 

1	 A group of predominantly interactive, electronically delivered training. IMI products include 

instructional software and software management tools used in support of instructional 

programs. IMI products are teaching and management tools and may be used in combination 

or individually. Used individually, not all IMI products can be considered interactive, multimedia, 

or instructional. However, IMI products, when used in combination with one another, are 

interactive, multimedia, and instructional. IMI technology is one of the primary technologies to 

be used in distance learning. 

see also:	 IMI Interactivity Levels 

Interagency Resources Representative (IARR) 

1	 An individual who may be assigned to or requested by an incident to serve as the sending unit's 

representative to oversee the care and treatment of crews, overhead, and equipment assigned 

to an incident. 

Interchangeable Course 

1	 A course developed by an interagency, all-hazard subject matter expert group containing the 

same learning objectives and content as an NWCG developed course. Interchangeable course 

do not require equivalency determination by a using agency and may have multiple course 

codes and/or numbers. These courses will be incorporated into IQCS/IQS and credit will be 

given for the NWCG course. 

Intermittent Smoke 

1	 Smoke which becomes visible only at intervals. 

Internal Load 

1	 Load carried inside the fuselage structure of an aircraft. 

Internal Payload 

1	 Allowable aircraft cabin load, in pounds, with full fuel and pilot in calm air at standard 

atmosphere. 

Inventoried Resources 

1	 Assigned resources which have checked in at the incident. 

Inversion 

1	 Atmospheric inversion. The departure from the usual increase or decrease with altitude of the 

value of an atmospheric property. In fire management usage, nearly always refers to an 

increase in temperature with increasing height. 

Also, the layer through which this departure occurs (also called inversion layer.) The lowest 

altitude at which the departure is found is called the base of the inversion. 

see also:	 Atmospheric Inversion
 

Atmospheric Stability
 

Stable Layer of Air
 

October 2014	 Page 109 
Glossary of Wildland Fire Terminology 

Iron Pipe Thread (IPT) 

1	 A tapered thread standard that is used for connecting various sizes of rigid pipe. This standard 

may be referred to as tapered iron pipe thread (TIPT), National pipe thread (NPT), iron pipe 

thread (IPT), or iron pipe standard thread (IPS). With tapered thread, the threads and pipe 

sealant perform the seal at the connection. This is opposed to straight thread connectors which 

use a gasket to form the seal. 

Island 

1	 An unburned area within a fire perimeter. 

Isobar 

1	 A line connecting points of equal atmospheric pressure on a weather map. 

Isotherm 

1	 A line connecting points of equal temperature on a weather map. 

Isothermal Layer 

1	 Layer through which temperature remains constant with elevation. 

I-Zone 

1 An area that, in relation to wildland/urban fire, has a set of conditions that provides the
 

opportunity for fire to burn from wildland vegetation to the home/structure ignition zone. 

see also: Wildland Urban Interface
 

- J -

Jettison 

1	 Disposing of cargo, fuel, water or retardant overboard to lighten an aircraft or to improve its 

stability. 

Job Hazard Analysis 

1	 A job hazard analysis identifies hazards associated with work projects and worksites, and 

identifies protective equipment or modified work procedures needed. 

Joint Information Center (JIC) 

1	 A facility established as the central point of contact for news media and interest parties to 

coordinate incident information activities at the scene of the incident. Public information officials 

from all participating federal, state, and local agencies should collocate at the JIC. 

Joint Information System (JIS) 

1	 A system that integrates incident information and public affairs into a cohesive organization 

designed to provide consistent, coordinated, timely information during crisis or incident 

operations. 

Jump Spot 

1	 Selected landing area for smokejumpers. 

Jump Suit 

1	 Approved protection suit worn for smokejumping. 

October 2014	 Page 110 
 

 

Glossary of Wildland Fire Terminology 

Jurisdiction 

1	 The range or sphere of authority. Public agencies have jurisdiction at an incident related to their 

legal responsibilities and authority for incident mitigation. Jurisdictional authority at an incident 

can be political/geographical (e.g., city, county, state or federal boundary lines), or functional 

(e.g., police department, health department, etc.). 

see also: Multijurisdiction Incident 

Jurisdictional Agency 

1	 The agency having land and resource management responsibility for a specific geographical or 

functional area as provided by federal, state or local law. 

- K -

Keetch-Byram Drought Index (KBDI) 

1	 An estimate (0-800) of the amount of precipitation (in 100ths of inches) needed to bring the top 

8 inches of soil back to saturation. A value of 0 is complete saturation of the soil, a value of 800 

means 8.00 inches of precipitation would be needed for saturation. In the 1988 version of 

NFDRS, outputs of KBDI are used to adjust live and dead fuel loadings. 

see also: Drought Index 

Kindling Point 

1	 Lowest temperature at which sustained combustion can be initiated for a specified substance. 

Also called ignition temperature. 

KnockDown 

1	 To reduce the flame or heat on the more vigorously burning parts of a fire edge. 

Knot 

1	 Nautical miles per hour, equal to 1.15 mph. 

- L -

Ladder Fuels 

1	 Fuels which provide vertical continuity between strata, thereby allowing fire to carry from surface 

fuels into the crowns of trees or shrubs with relative ease. They help initiate and assure the 

continuation of crowning. 

Land Occupancy Fire 

1	 Fire started as a result of land occupancy for agricultural purposes, industrial establishment, 

construction, maintenance and use of rights-of-way, and residences, except equipment use and 

smoking. 

Land Use Plan 

1	 A set of decisions that establish management direction for land within an administrative area; an 

assimilation of land-use-plan-level decisions developed through the planning process regardless 

of the scale at which the decisions were developed. 

Land/Resource Management Plan (L/RMP) 

1	 A document prepared with public participation and approved by an agency administrator that 

provides general guidance and direction for land and resource management activities for an 

administrative area. The L/RMP identifies the need for fire’s role in a particular area and for a 

specific benefit. The objectives in the L/RMP provide the basis for the development of fire 

management objective and the fire management program in the designated area. 

October 2014	 Page 111 
 

 

Glossary of Wildland Fire Terminology 

Lapse Rate 

1 Change of an atmospheric variable (temperature unless specified otherwise) with height. 

Large Aircraft 

1 Aircraft in which maximum certified gross weight at take-off exceeds 12,500 pounds. 

Large Fire 

1 For statistical purposes, a fire burning more than a specified area of land e.g., 300 acres. 

2 A fire burning with a size and intensity such that its behavior is determined by interaction 

between its own convection column and weather conditions above the surface. 

Large Fire-Day 

1 In FireFamily Plus, a day with both a weather observation and at least one large (as defined by 

the user) fire. 

see also: Fire-Day 

Multiple Fire-Day 

Lateral Fire 

1 Rate or spread and intensity of a fire usually falling somewhere in between advancing and 

backing with spread lateral to the main direction of fire travel. Also called: flanking fire. 

synonym: Flank Fire 

Leach 

1	 Removal of soluble constituents from ashes or soil by percolation of water. 

Lead Line 

1	 Line or set of lines made of rope, webbing, or cable and used in helicopter external load 

operations; usually placed between a swivel or the cargo hook and the load. 

Lead Plane 

1	 Aircraft with pilot used to make trial runs over the target area to check wind, smoke conditions, 

topography and to lead air tankers to targets and supervise their drops. 

Leader 

1	 The ICS title for an individual responsible for a task force, strike team, or functional unit. 

Leader's Intent 

1	 A concise statement that outlines what individuals must know in order to be successful for a 

given assignment. The intent communicates three essential pieces of information:

 - Task – What is the goal or objective

 - Purpose – Why it is to be done

 - End state – How it should look when successfully completed 

Leadership 

1	 The art of providing purpose, direction, and motivation to a group of people in order to 

accomplish a mission and improve the organization. Leaders provide purpose by clearly 

communicating their intent and describing the desired end state of an assignment to their 

followers. Leaders provide direction by maintaining standards of performance for their followers. 

Leaders provide motivation by setting the example for their followers. 

Leapfrog Method 

1	 A system of organizing workers in fire suppression in which each crew member is assigned a 

specific task such as clearing or digging fireline on a specific section of control line, and when 

that task is completed, passes other workers in moving to a new assignment. 

October 2014	 Page 112 
 

Glossary of Wildland Fire Terminology 

Learning Content Management System (LCMS) 

1 Any system that keeps learner information, can launch and communicate with SCOs, and can 

interpret instructions that tell it which SCO comes next. 

see also: Shareable Content Object 

Learning Objective 

1 A description of the intended outcome of a training class, program, or evolution. The learning 

objective identifies the condition, the task, and the standard to which the student much achieve. 

see also: Task 

Learning Objects 

1	 Reusable learning objects represent an alternative approach to content development. In this 

approach, content is broken down into chunks. From a pedagogical perspective, each chunk 

might play a specific role within an instructional design methodology. Such chunks are called 

learning objects. There is no standard for the size (or granularity) of a learning object. Larger 

learning objects are typically harder to reuse, and smaller learner objects save less work for 

those who reuse them. Normally the happy medium has been estimated as between five and 

fifteen minutes of learning material. The requirements for each chunk are: 

1) Each chunk must be able to communicate with learning systems using a standardized 

method that does not depend on the system 

2) What happens within a chunk is the chunk's business. 

3) How a learner moves between chunks is controlled by the learning system. 

4) Each chunk must have a description (metadata tag) that enables designers to search for and 

find the right chunk for the right job. 

see also: Shareable Content Object 

Legitimate Smoke 

1	 Smoke from any authorized use of fire (e.g., locomotive, industrial operations, permitted debris 

burning). 

Level of Service 

1	 Amount of fire prevention and fire suppression supplied; may be expressed several ways (e.g., 

percent of people or buildings protected, area protected, dollar value of property protected, 

firefighters per capita, water flow capability). 

Liaison Officer (LOFR) 

1	 This ICS position is responsible for serving as the incident's point of contact for coordinating with 

agency representatives from assisting and cooperating agencies. Reports to the Incident 

Commander and is a member of the Command Staff. This position may have one or more 

assistants assigned. 

see also: Agency Representative 

Life-Safety 

1	 Refers to the joint consideration of both the life and physical well-being of individuals. 

Lifting Processes 

1	 Any of the processes that lead to upward vertical motion in the atmosphere. These processes 

may include low level convergence, heating or thermal convection, orographic lifting over the 

mountains, and frontal lifting. 

Light (Fine) Fuels 

1	 Fast-drying fuels, generally with a comparatively high surface area-to-volume ratio, which are 

less than 1/4-inch in diameter and have a timelag of 1 hour or less. These fuels readily ignite 

and are rapidly consumed by fire when dry. 

October 2014	 Page 113 
 

 

 

 

 

Glossary of Wildland Fire Terminology 

Light Wind 

1	 Wind speed less than 7 mph (6 knots) measured at 20 feet above ground. At eye level, light 

winds are less than 3 mph (3 knots). 

Lightning Activity Level (LAL) 

1	 Part of the National Fire Danger Rating System (NFDRS). A number, on a scale of 1 to 6, which 

reflects frequency and character of cloud-to-ground lightning (forecasted or observed). The 

scale for 1 to 5 is exponential, based on powers of 2 (i.e., LAL 3 indicates twice the lightning of 

LAL 2). LAL 6 is a special category for dry lightning and is closely equivalent to LAL 3 in strike 

frequency. 

Lightning Fire 

1	 Wildfire caused directly or indirectly by lightning. 

Lightning Fire Occurrence Index 

1	 Part of the National Fire Danger Rating System (NFDRS). Numerical rating of the potential 

occurrence of lightning-caused fires. 

Lightning Risk (LR) 

1	 Part of the National Fire Danger Rating System (NFDRS). A number related to the expected 

number of cloud-to-ground lightning strokes to which a protection unit is expected to be exposed 

during the rating period. The LR value used in the occurrence index includes an adjustment for 

lightning activity experienced during the previous day to account for possible holdover fires. 

Lightning Risk Scaling Factor 

1	 Part of the National Fire Danger Rating System (NFDRS). Factor derived from local 

thunderstorm and lightning-caused fire records that adjusts predictions of the basic lightning fire 

occurrence model to local experience, accounting for factors not addressed directly by the 

model (e.g., susceptibility of local fuels to ignition by lightning, fuel continuity, topography, 

regional characteristics of thunderstorms). 

Lightning Stroke Counter 

1	 Electronic sensor used to record the number of lightning strokes within a predetermined range 

over a specified period of time. 

Lightweight Ignition Source 

1	 Objects that tend to rest on the surface of the materials first ignited. I.e., matches, cigarette 

butts, flat metal fragments, etc. 

Limbing 

1	 Removing branches from a felled or standing tree, or from brush. 

Limited Containment 

1	 Halting of fire spread at the head, or that portion of the flanks of a prescribed fire that is
 

threatening to exceed prescription criteria, and ensuring that this spread rate will not be
 

encountered again; does not indicate mopup.
 

Line Cutter 

1	 Fire crew member in the progressive method of line construction who cuts and clears away 

brush, small saplings, vines, and other obstructions in the path of the fireline; usually equipped 

with ax or brush hook, or pulaski. 

Line Officer 

1 Managing officer, or designee, of the agency, division thereof, or jurisdiction having statutory 

responsibility for incident mitigation and management. 

see also: Agency Administrator 

October 2014	 Page 114 
 

 

 

 

Glossary of Wildland Fire Terminology 

Line Scout 

1	 A firefighter who determines the location of a fire line. 

Lined Fire Hose 

1	 Fire hose with a smooth inner coating of rubber or plastic to reduce friction loss. 

Liquid Concentrate (LC) 

1	 Liquid phosphate fertilizers used as fire retardants, usually diluted three to five times prior to 

application. 

Litter 

1 The top layer of forest floor, composed of loose debris of dead sticks, branches, twigs, and 

recently fallen leaves or needles; little altered in structure by decomposition. 

see also: Duff 

Humus 

Little Change 

1	 Insignificant change in wind speed, direction, and temperature (less than 5 degrees) and 

relative humidity (less than five percent), respectively. When used as a general statement in a 

long-range forecast, all four criteria apply. 

Live Fuel Moisture Content 

1	 Ratio of the amount of water to the amount of dry plant material in living plants. 

Live Fuels 

1	 Living plants, such as trees, grasses, and shrubs, in which the seasonal moisture content cycle 

is controlled largely by internal physiological mechanisms, rather than by external weather 

influences. 

Live Herbaceous Moisture Content 

1	 Ratio of the amount of water to the amount of dry plant material in herbaceous plants, i.e., 

grasses and forbs. 

Live Line 

1 Hose line filled with water under pressure and ready to use. 

synonym: Charged Line
 

see also: Live Reel
 

Live Reel 

1	 Hose line or reel on a fire engine, carried preconnected to the pump, ready for use without 

making connections to pump or attaching nozzle. 

Live Run 

1	 Indicates that the air tanker has the target in sight and will make a retardant drop on this run 

over the target. 

Live Woody Moisture Content 

1	 Ratio of the amount of water to the amount of dry plant material in shrubs. 

Living Fuels 

see:	 Live Fuels 

Load and Hold 

1	 An order given to the airtanker pilot to pick up another load of retardant or water and hold at the 

reload base. The tanker is still committed to the fire. 

October 2014	 Page 115 
 

 

 

Glossary of Wildland Fire Terminology 

Load and Return 

1	 Order given to the air tanker pilot to pick up another load of fire retardant or water and return to 

the fire. 

Load Calculation Form 

1	 An agency form used to calculate helicopter allowable payload. 

Loading Pad 

1	 Concrete pad at a retardant base on which aircraft stand when being loaded. 

Loadmaster 

1	 Individual responsible to the Deck Coordinator for the manifesting, loading and unloading of 

personnel, equipment and cargo. 

Local Agency 

1	 Any agency having jurisdictional responsibility for all or part of an incident. 

Local Resource 

1	 Resources within a dispatch center's area of responsibility. 

Local Responsibility Area 

1	 Lands on which neither the state nor the federal government has any legal responsibility for 

providing fire protection. 

Local Winds 

1 Winds which are generated over a comparatively small area by local terrain and weather. They 

differ from those which would be appropriate to the general pressure pattern. 

see also: General Winds 

Slope Winds 

Logging Debris 

1 Unwanted tree parts (crowns, logs, uprooted stumps) remaining after harvest.
 

see also: Activity Fuels
 

Logistics Section 

1	 The ICS section responsible for providing facilities, services, and supplies in support of an
 

incident.
 

Logistics Section Chief (LSC1 or LSC2) 

1	 This ICS position is responsible for supervising the Logistic Section. Reports to the Incident 

Commander and is a member of the General Staff. This position may have one or more 

deputies assigned. 

see also: Logistics Section 

Longline 

1	 A line or set of lines, usually in 50' increments, used in external load operations that allow the 

helicopter to place loads in areas in which the helicopter could not safely land. 

Long-Range Forecast 

1	 Fire weather forecast for a period greater than five days in advance. 

Long-Range Spotting 

1	 Large glowing firebrands are carried high into the convection column and then fall out downwind 

beyond the main fire starting new fires. Such spotting can easily occur 1/4 mile or more from 

the firebrand's source. 

October 2014	 Page 116 
 

 

Glossary of Wildland Fire Terminology 

Long-Term Fire Danger 

1	 The results of those factors in fire danger affecting long-term planning; involves consideration of 

past records and conditions and probable future trends. 

Long-Term Fire Retardant 

1	 Chemical that inhibits combustion primarily through chemical reactions between products of 

combustion and the applied chemicals, even after the water component has evaporated. Other 

chemical effects also may be achieved, such as film-forming and intumescence. 

Lookout 

1 A person designated to detect and report fires from a vantage point. 

2 A location from which fires can be detected and reported. 

3 A fire crew member assigned to observe the fire and warn the crew when there is danger of 

becoming trapped. 

Lookout Dispatcher 

1	 Person combining the functions of lookout and dispatcher. 

Lookout Firefighter 

1	 Person combining the functions of lookout and firefighter. 

Lookout Patrol 

1	 Person who travels along ridges or other vantage points to discover, detect, report, and
 

suppress fires.
 

Lookout Point 

1	 Vantage point selected for fire detection or observation. 

Lookout Tower 

1	 Structure that elevates a person above nearby obstructions to sight for fires; generally capped 

by some sort of house or cupola. 

Lookout(s), Communication(s), Escape Route(s), and Safety Zone(s) (LCES) 

1	 Elements of a safety system used by fire fighters to routinely assess their current situation with 

respect to wildland firefighting hazards. 

Lopping 

1	 After felling, cutting branches, tops, and unwanted boles into lengths such that resultant logging 

debris will lie close to the ground. 

Lopping and Scattering 

1	 Lopping logging debris and spreading it more or less evenly over the ground. 

Lost Line 

1	 Any part of a fireline rendered useless by a breakover of the fire. 

Low 

1	 An area of relatively low atmospheric pressure in which winds tend to move in a 

counterclockwise direction, spiraling in toward the low’s center. 

Low Expansion 

1	 Foam with an expansion between 1:1 and 20:1. 

October 2014	 Page 117 
 

 

Glossary of Wildland Fire Terminology 

- M -

Macro Scale Indicators 

1 Large single indicators or overall patterns of indicators that are readily visible from a distance. 

Macroclimate 

1	 General large-scale climate of a large area or country as distinguished from smaller scale
 

mesoclimate and microclimate. 

Main Ridge 

1	 Prominent ridgeline separating river or creek drainages. Usually has numerous smaller ridges 

(spur) extending outward from both sides. 

Major Disaster 

1	 Any natural catastrophe or, regardless of cause, any fire, flood, or explosion, in any part of the 

United States, which in the determination of the President causes damage of sufficient severity 

and magnitude to warrant major disaster assistance. 

Major Repair (Aviation) 

1	 A repair (1) that, if improperly done, might appreciably affect weight, balance, structural 

strength, or other qualities affecting airworthiness or (2) that is not done according to accepted 

practices or cannot be done by elementary operations. 

Male Coupling 

1	 An externally threaded hose nipple which fits in the thread of a female (internally threaded) 

swivel coupling of the same pitch and diameter. Nozzles attach to this type of coupling. 

Management Action Points 

1	 Geographic points on the ground or specific points in time where an escalation or alternative of 

management actions is warranted. These points are defined and the management actions to be 

taken are clearly described in an approved Prescribed Fire Plan. Timely implementation of the 

actions when the fire reaches the action point is generally critical to successful accomplishment 

of the objectives. Also called Trigger Points. 

Management by Objectives 

1	 In ICS, this is a top-down management activity which involves a three-step process to achieve 

the incident goal. The steps are: establishing the incident objectives, selection of appropriate 

strategy(s) to achieve the objectives; and the tactical direction associated with the selected 

strategy. Tactical direction includes: selection of tactics, selection of resources, resource 

assignments and performance monitoring. 

Management Requirements 

1	 The technical and scientific specifications for management activities or potential actions 

mandated by the agency administrator and defined in land/resource management plans. 

Management requirements are derived from land/resource management plan and fire
 

management plan standards and guidelines information. 

Managers 

1	 Individuals within ICS organizational units that are assigned specific managerial responsibilities, 

e.g., staging area manager or camp manager. 

Manual Weather Station 

1 A non-telemetered weather station that provides one observation every 24 hours for manual 

entry into WIMS. 

see also: Automatic Weather Station 

October 2014	 Page 118 
 

 

Glossary of Wildland Fire Terminology 

Manually Regulated 

1	 A proportioning method or device that requires a manual adjustment to maintain a desired mix 

ratio over a changing range of water flows and pressures. 

Marine Air 

1	 Air which has a high moisture content and the temperature characteristics of an ocean surface 

due to extensive exposure to that surface. An intrusion of marine air will moderate fire 

conditions. Absence of marine air in coastal areas may lead to more severe fire danger. 

Marine Climate 

1	 Regional climate under the predominant influence of the sea, that is, a climate characterized by 

marine air; the opposite of a continental climate. 

Maritime Air 

1	 Air which has assumed high moisture content and the temperature characteristics of a water 

surface due to extensive exposure to that surface. 

Mass Arsonist 

1 An offender who sets three or more fires at the same location during a limited period of time. 

Mass Fire 

1 A fire resulting from many simultaneous ignitions that generates a high level of energy output. 

Master Fire Chronology 

1	 Chronological listing of the dates of fires documented in a designated area, the dates being 

corrected by crossdating. Size of the area must be specified. Also called composite fire interval. 

Material First Ignited 

1	 The fuel that is first set on fire by the heat of ignition; to be meaningful, both a type of material 

and form of material should be identified. 

Mathematical Model 

1 A model that is a quantitative and mathematical representation or simulation which attempts to 

describe the characteristics or relationship of physical events. 

see also: Model 

Mattock 

1	 Hand tool with a narrow hoeing surface at one end of the blade and a pick or cutting blade at the 

other end; used for digging and grubbing. 

Maximum Certified Gross Weight 

1	 Absolute maximum allowable gross weight for an aircraft as established by the manufacturer 

and approved by the FAA. 

Maximum Computed Gross Weight 

1	 Computed gross weight for an aircraft, obtained from the appropriate performance chart, which 

is the maximum gross weight appropriate to the applicable circumstance of configuration and/or 

environmental conditions. 

Maximum Dry Bulb Temperature 

1 The highest value for dry bulb temperature measured at the observation site during the
 

preceding 24-hour period. 

see also: Minimum Dry Bulb Temperature
 

Maximum Manageable Area (MMA) 

1	 The maximum geographic limits of spread within which a wildland fire is allowed to spread. 

October 2014	 Page 119 
 

 

Glossary of Wildland Fire Terminology 

Maximum Relative Humidity 

1 The highest value for relative humidity measured at the observation site during the preceding 24­

hour period. 

see also: Minimum Relative Humidity 

May Day 

1	 International distress signal/call. When repeated three times it indicates imminent and grave 

danger and that immediate assistance is required. 

Mcleod 

1	 A combination hoe or cutting tool and rake, with or without removable blades. 

Mean Fire Return Interval 

1	 Arithmetic average of all fire intervals in a given area over a given time. 

Mean Sea Level (MSL) 

1	 Average height of the surface of the sea for all stages of the tide over a 19-year period. NOTE: 

when the abbreviation MSL is used in conjunction with a number of feet, it implies altitude above 

sea level (e.g., 1000 feet MSL). 

Measured Woody Fuel Moisture 

1	 Moisture content of the small branch wood and foliage of live woody plants, expressed as a 

percentage of the oven dry weight of the sample, collected monthly and used to supplement 

NFDRS modeled outputs. 

see also: Woody Fuel Moisture 

Medical Director 

1	 A physician who assumes the ultimate responsibility for the patient care aspects of the incident 

EMS program. 

Medical Unit 

1	 Functional unit within the logistics section that is responsible for the emergency medical and 

occupational health care of incident personnel. Some incident management teams have placed 

this unit under safety. 

Medical Unit Leader (MEDL) 

1 The ICS position responsible for supervising the Medical Unit. Reports to the Service Branch 

Director or Logistics Section Chief. 

see also: Medical Unit 

Medium Expansion 

1	 Foam with an expansion between 21:1 and 200:1. 

Medium-range Forecast 

1	 A forecast for a period extending from about two days to five days or a week in advance; there 

are no absolute limits to the period embraced by this definition. 

Medivac 

1	 Mobile medical treatment and transportation. 

Message Center 

1	 The message center is part of the incident communications center and is collocated or placed 

adjacent to it. It receives, records, and routes information about resources reporting to the 

incident, resource status, and administrative and tactical traffic. 

October 2014	 Page 120 
 

 

Glossary of Wildland Fire Terminology 

Methodology 

1	 A set of standardized procedures and practices that have been peer-reviewed and have
 

received general acceptance by the profession. 

Micro Scale Indicators 

1	 Small individual indicators and patterns that are not easily observable without close observation 

or magnification. 

Micro-Remote Environmental Monitoring System (Micro-REMS) 

1	 Mobile weather monitoring station. Each unit consists of a shipping container, solar panel, 

battery, temperature/relative humidity sensor, wind mast, wind direction/speed sensor, data 

logger and radio. A Micro-REMS usually accompanies an incident meteorologist and ATMU to 

an incident. 

see also: Incident Meteorologist 

Mid-Flame Windspeed 

1	 The speed of the wind measured at the midpoint of the flames, considered to be most 

representative of the speed of the wind that is affecting fire behavior. 

Military Operations Area (MOA) 

1	 Military Operations Area found on aeronautical charts. 

Military Time 

1	 The 24-hour clock system where midnight is 2400, one minute after midnight is 0001 and
 

progresses to 2400 daily.
 

Millibar 

1	 A unit of pressure equal to a force of 1,000 dynes per square centimeter. (A dyne is the force 

that would give a free mass of one gram an acceleration of one centimeter per second per 

second.) 

Mineral Ash 

1	 The residue of mineral matter left after complete combustion of wood (wood ash) or other
 

organic material; consists largely of oxides, carbonates, and phosphates of Ca, K and Mg, 

together with other compounds. 

Mineral Soil 

1	 Soil layers below the predominantly organic horizons; soil with little combustible material. 

Minimum Cost Suppression Alternative 

1	 The alternative that achieves incident objectives, consistent with priority for firefighter and public 

safety, and is least expensive when considering expected costs for fire suppression and 

emergency stabilization and/or rehabilitation. 

Minimum Dry Bulb Temperature 

1 The lowest value for dry bulb temperature measured at the observation site during the
 

preceding 24-hour period. 

see also: Maximum Dry Bulb Temperature
 

Minimum Impact Suppression Techniques (MIST) 

1	 The application of strategy and tactics that effectively meet suppression and resource objectives 

with the least environmental, cultural and social impacts. 

Minimum Relative Humidity 

1 The lowest value for relative humidity measured at the observation site during the preceding 24­

hour period. 

see also: Maximum Relative Humidity 

October 2014	 Page 121 
 

 

Glossary of Wildland Fire Terminology 

Miscellaneous Fire 

1	 Fire of known cause that cannot be properly classified into any of the eight standard causes of 

fires. 

Mitigation Actions 

1	 Actions that are implemented to reduce or eliminate (mitigate) risks to persons, property or 

natural resources. These actions can include mechanical and physical tasks, specific fire 

applications, and limited suppression actions. Mitigation actions may include: fireline 

construction, fuel treatments and reductions, fuel breaks or barriers around critical or sensitive 

sites or resources, and creating "black lines" through the use of controlled burnouts to limit fire 

spread and behavior. 

Mix Ratio 

1	 The ratio of liquid foam concentrate to water, usually expressed as a percent. 

Mixing 

1	 A random exchange of air parcels on any scale from the molecular to the largest eddy. 

Mixing Chamber 

1	 A tube, constructed with deflectors or baffles, that mixes foam solution and air to produce tiny, 

uniform bubbles in a short distance (1 to 2 ft). 

Mixing Height 

1	 Measured from the surface upward, the height to which relatively vigorous mixing occurs due to 

convection. Also called mixing depth. 

Mixing Layer 

1	 That portion of the atmosphere from the surface up to the mixing height. This is the layer of air, 

usually below a stable layer, within which pollutants are mixed by turbulence and diffusion. Also 

called mixed layer. 

see also:	 Transport Wind Speed
 

Ventilation Factor
 

Mixmaster 

1	 The person in charge of fire retardant mixing operations with responsibility for quantity and 

quality of the slurry and for the loading of aircraft. 

Mobile Radio 

1	 A two way radio unit on mobile apparatus (instead of base stations), usually semi-permanently 

attached to the apparatus. 

Mobile Weather Unit Forecast 

1	 A special fire weather forecast for a specific fire prepared by a meteorologist on site at or near 

the fire area. 

Mobilization 

1	 The process and procedures used by all organizations, federal, state and local, for activating, 

assembling, and transporting all resources that have been requested to respond to or support 

an incident. 

Mobilization Center 

1	 An off-incident location at which emergency service personnel and equipment are temporarily 

located pending assignment, release, or reassignment. 

October 2014	 Page 122 
 

Glossary of Wildland Fire Terminology 

Mobilization Guide 

1	 A written description of procedures used by federal, state, and local organizations for activating, 

assembling, and transporting resources that have been requested to respond to or support an 

incident. 

Model 

1 A simplified or generalized representation of reality; a description, analogy, picture, or
 

hypothesis to help visualize something that cannot be directly observed. 

see also: Conceptual Model
 

Mathematical Model
 

Model Arson Law 

1	 Model legislation, recommended by the Fire Marshals' Association of North America and 

adopted in most states, dealing with the subject of arson. 

Model Fireworks Law 

1	 Model legislation recommended by the Fire Marshals' Association of North America and
 

adopted by many states, regulating display of fireworks. 

Modular Airborne Firefighting System (MAFFS) 

1	 A manufactured unit consisting of five interconnecting tanks, a control pallet, and a nozzle pallet, 

with a capacity of 3,000 gallons, designed to be rapidly mounted inside an unmodified C-130 

(Hercules) cargo aircraft for use in cascading retardant chemicals on wildfires. 

Moist Adiabatic Lapse Rate 

1	 Rate of decrease of temperature with increasing height of an air parcel lifted at saturation via 

adiabatic process through an atmosphere in hydrostatic equilibrium. Rate varies according to 

the amount of water vapor in the parcel and is usually between 2.0 and 5.0 degrees F per 1000 

feet (3.6 and 9.2 degrees C per 1000 meters). 

Moisture of Extinction 

1	 The fuel moisture content, weighed over all the fuel classes, at which the fire will not spread. 

Also called extinction moisture content (EMC). 

Monitor 

1	 A turret-type nozzle usually mounted on an engine. 

Monitoring 

1	 The orderly collection, analysis, and interpretation of environmental data to evaluate 

management's progress toward meeting objectives, and to identify changes in natural systems. 

Monitoring is also conducted on wildland fires to observe fire effects, fire behavior, or both. For 

example, the work done by Fire Effects Monitor (FEMO) or Field Observer (FOBS) positions. 

Monsoon Climate 

1	 Climate characterized by (a) a long winter-spring dry season which includes a "cold season" 

followed by a short "hot season" immediately preceding the rains, (b) a summer and early 

autumn rainy season which is usually very wet (but highly variable from year to year), and (c) a 

secondary maximum of temperature immediately after the rainy season. 

Mop Up 

1	 Extinguishing or removing burning material near control lines, felling snags, and trenching logs 

to prevent rolling after an area has burned, to make a fire safe, or to reduce residual smoke. 

Mop Up Crew 

1	 A portion or all of a regular fire crew assigned to mop up work after the fire or a portion of the 

fire has been contained or controlled. 

October 2014	 Page 123 
Glossary of Wildland Fire Terminology 

Mop Up Time 

1	 Elapsed time from containment or control of a fire until mop up is complete. 

Mosaic 

1	 The intermingling of plant communities and their successional stages in such a manner as to 

give the impression of an interwoven design. 

Most Efficient Level (MEL) 

1	 The fire management program budget level that results in the minimum cost plus net value 

change. 

Move-up 

1	 System of redistributing remaining personnel and equipment following dispatch of other forces 

among a network of fire stations to provide the best possible response within the fire 

department's direct protection area in the event of additional calls for emergency assistance. 

Moveup Method 

1	 Progressive method of fireline construction on a wildfire without changing relative positions in 

the line. Work is begun with a suitable space between workers; whenever one worker overtakes 

another, all of those ahead move one space forward and resume work on the uncompleted part 

of the line. The last worker does not move ahead until work is completed in his/her space. 

Forward progress of the crew is coordinated by a crew boss. 

synonym: Bumpup Method 

Multi-Agency Coordinating Group (MAC Group) 

1	 A national, regional, or local management group for interagency planning, coordination, and 

operations leadership for incidents. Provides an essential management mechanism for strategic 

coordination to ensure incident resources are efficiently and appropriately managed in a cost 

effective manner. 

Multi-Agency Coordination (MAC) 

1	 A generalized term which describes the functions and activities of representatives of involved 

agencies and/or jurisdictions who come together to make decisions regarding the prioritizing of 

incidents, and the sharing and use of critical resources. The MAC organization is not a part of 

the on-scene ICS and is not involved in developing incident strategy or tactics. 

Multi-Agency Coordination System (MACS) 

1	 MACS provides the framework to support coordination for incident prioritization, critical resource 

allocation, communication systems integration, and information coordination. MACS 

components include facilities, equipment, emergency operating centers EOCs), specific multiagency coordination entities, personnel, procedures, and communications. 

Multi-Agency Incident 

1 An incident where one or more agencies assist a jurisdictional agency or agencies. May be 

single or unified command. 

see also: Jurisdiction 

Multicom 

1	 A VHF/AM aircraft radio frequency (122.9 MHz) assigned by the FAA for use in air-to-air 

communications. 

Multijurisdiction Incident 

1 An incident requiring action from multiple agencies that have a statutory responsibility for
 

incident mitigation. In ICS these incidents will be managed under unified command.
 

see also: Jurisdiction
 

October 2014	 Page 124 
Glossary of Wildland Fire Terminology 

Multiple Fire Situation 

1	 High fire frequency over a short period of time in an administrative unit, usually overtaxing the 

normal initial attack capability of the unit. 

Multiple Fire-Day 

1 In FireFamily Plus, a day with both a weather observation and a number of fires equal to or 

greater than that determined by the user to be a significant workload. 

see also: Fire-Day 

Large Fire-Day 

Multiple Points of Origin 

1	 Two or more separate points of fire origins at a fire scene; strong indication of arson. 

Mutual Aid 

1	 Assistance in firefighting or investigation by fire agencies, without regard for jurisdictional
 

boundaries. 

Mutual Aid Agreement 

1	 Written agreement between agencies and/or jurisdictions in which they agree to assist one 

another upon request, by furnishing personnel and equipment. 

Mutual Threat Zone 

1	 A geographical area between two or more jurisdictions into which those agencies would
 

respond on initial attack. Also called mutual response zone or initial action zone. 

- N -

Napalm 

1	 An incendiary mixture with a jelling agent used in flamethrowers and bombs. 

National Advanced Resources Technology Center (NARTC) 

1	 Multi-agency training facility at Pinal Air Park, Marana, Arizona, which specializes in 

presentation of national-level fire management training courses. 

National Ambient Air Quality Standards (NAAQS) 

1	 A legal limit on the level of atmospheric contamination. The level is established as the 

concentration limits needed to protect all of the public against adverse effects on public health 

and welfare, with an adequate safety margin. Primary standards are those related to health 

effects. Secondary standards are designed to protect the public welfare from effects such as 

visibility reduction, soiling, material damage and nuisances. 

National Association of State Foresters (NASF) 

1	 An organization consisting of the State Forester from each state and territory which promotes 

cooperation in forestry matters between the states and territories, the federal government and 

private forestry groups. It promotes legislation, programs and activities which will advance the 

practice of forestry and use of forest products. 

National Environmental Satellite, Data and Information Service (NESDIS) 

1	 A National Oceanic and Atmospheric Administration Agency. 

National Fire Codes (NFC) 

1	 The collected technical fire protection standards prepared by various committees of the National 

Fire Protection Association and published annually in 15 volumes. 

October 2014	 Page 125 
Glossary of Wildland Fire Terminology 

National Fire Danger Rating System (NFDRS) 

1 A uniform fire danger rating system that focuses on the environmental factors that control the 

moisture content of fuels. 

see also: Fire Danger Rating System 

National Fire Protection Association (NFPA) 

1 A private, non-profit organization dedicated to reducing fire hazards and improving fire service. 

National Fire Protection Association Standards (NFPA) 

1	 Standards of the National Fire Protection Association are frequently adopted by insurance 

agencies such as the National Board of Fire Underwriters as a basis for their regulations and 

used as a guide for municipal, state, or provincial laws, ordinances, and regulations. 

National Forest Lands 

1	 Public lands, generally forest, range, or other wildland, administered by the Forest Service, 

USDA. 

National Forest System 

1	 Consists of all national forest lands, the national grasslands and land utilization projects 

administered under title III of the Bankhead-Jones Farm Tenant Act, and other interests as 

defined in Section 9 of the National Forest Management Act of 1976. 

National Interagency Coordination Center (NICC) 

1	 Coordinates allocation of resources to one or more coordination centers or major fires within the 

nation. Located in Boise, Idaho. 

National Interagency Fire Center (NIFC) 

1	 A facility located at Boise, Idaho, jointly operated by several federal agencies, dedicated to 

coordination, logistical support, and improved weather services in support of fire management 

operations throughout the United States. 

National Interagency Fire Management Integrated Database (NIFMID) 

1	 The archive of daily weather observations from WIMS. 

National Interagency Incident Management System (NIIMS) 

1	 An NWCG developed program consisting of five subsystems which collectively provide a total 

systems approach to all-risk incident management. The subsystems are: The Incident 

Command System, Training, Qualifications and Certification, Supporting Technologies, and 

Publications Management. 

National Park 

1	 A federal reservation administered by the National Park Service of the U.S. Department of the 

Interior in order to conserve unique scenery, flora and fauna, and any natural and historic 

objects within its boundaries for public enjoyment in perpetuity. 

National Pipe Straight Hose Thread (NPSH) 

1	 Also known as National Pipe Straight Mechanical (NPSM) thread. This is a straight 

(nontapered) thread standard with the same threads per inch as the appropriate size iron pipe 

thread. It requires a gasket to seal and is the thread standard used by most U.S. industry. 

National Resource Lands (NRL) 

1	 Public lands administered by the Bureau of Land Management, U.S. Department of the Interior. 

National Response Plan 

1	 A plan that integrates federal government domestic prevention, preparedness, response, and 

recovery plans into one all-discipline, all-hazard plan. 

October 2014	 Page 126 
 

Glossary of Wildland Fire Terminology 

National Standard Thread (NH) 

1	 Abbreviated (NH) for national hose. Specifically defined screw thread used on fire hose 

couplings.
 

National Wildfire Coordinating Group (NWCG) 

1	 An intergovernmental body that provides national leadership to develop, maintain and 

communicate standards, guidelines, qualifications, training, and other capabilities that enable 

interoperable operations among federal and non-federal entities for wildland fire program 

management. 

see also: NWCG Standard 

National Wildlife Refuge System 

1	 All lands, waters and interests therein administered by the Fish and Wildlife Service for the 

protection and conservation of fish and wildlife, including those that are threatened with 

extinction. 

Native Species 

1	 A species which is a part of the original fauna or flora of the area in question. 

Natural Barrier 

1	 Any area where lack of flammable material obstructs the spread of wildfires. 

Natural Fuels 

1 Fuels resulting from natural processes and not directly generated or altered by land 

management practices. 

see also: Activity Fuels
 

Near Miss 

1	 Any potential accident which, through prevention, education, hazard reduction, or luck, did not 

occur. 

NESDIS ID 

1	 An 8-character identifier assigned by NESDIS that becomes the RAWS identification number for 

use with the GOES satellite. 

Net Value Change (NVC) 

1	 The sum of the changes in the value of natural resources affected by a fire. The basis for
 

computing NVC is each resource's fire-induced value change (pluses and minuses) as
 

computed and expressed on a per unit basis. 

Neutral Atmosphere 

1	 Condition in which temperature decrease with increasing altitude is equal to the dry adiabatic 

lapse rate (i.e., the atmosphere neither aids nor hinders large-scale vertical motion). 

Night (Aviation) 

1	 The time between the end of evening civil twilight and the beginning of morning civil twilight, as 

published in the American Air Almanac, converted to local time. 

Nitrogen Dioxide (NO2) 

1	 The result of nitric oxide combining with oxygen in the atmosphere. A major component of 

photochemical smog. 

Nitrogen Oxide (NO) 

1	 Product of combustion from transportation and stationary sources and a major contributor to 

acid deposition and the formation of ground level ozone in the troposphere. 

October 2014	 Page 127 
 

 

Glossary of Wildland Fire Terminology 

Nomex ® 

1	 Trade name for a fire resistant synthetic material used in the manufacturing of flight suits and 

pants and shirts used by firefighters. Aramid is the generic name. 

Non-attainment Area 

1	 An area identified by an air quality regulatory agency through ambient air monitoring (and 

designated by the Environmental Protection Agency), that presently exceeds federal ambient air 

standards. 

Noncommercial Forest Land 

1	 Forest land incapable of yielding crops of commercially useful wood because of adverse site 

conditions, or productive forest land withdrawn from commercial timber use through statute or 

administrative regulation. 

Nonflammable 

1 Material unlikely to burn when exposed to flame under most conditions. 

see also: Flammable
 

Nonprecision Approach Procedure 

1 Standard aircraft instrument approach procedure in which no electronic glide slope is provided. 

Nonstatistical Fire 

1	 Any fire not posing a threat to resources or property of the jurisdictional agency, regardless of 

whether action was taken by the agency. 

Normal Fire Season 

1 A season when weather, fire danger, and number and distribution of fires are about average. 

2 Period of the year that normally comprises the fire season based on historical fire occurrence. 

Normalized Difference Vegetation Index (NDVI) 

1 A satellite observation-derived value that is sensitive to vegetative growth, measured at 1.1 km 

(0.6 mile) spatial and 1 week temporal scales. 

Notice to Airmen (NOTAM) 

1	 Notice identified as either a NOTAM or Airmen Advisory containing information concerning the 

establishment, condition, or change in any component of, or hazard in, the National Airspace 

System, the timely knowledge of which is essential to personnel concerned with flight 

operations. 

Nozzle Aspirated Foam System 

1	 A foam generating device that mixes air at atmospheric pressure with foam solution in a nozzle 

chamber. 

Nozzle Operator 

1	 A person assigned to operate a fire hose nozzle, usually on a hand line. 

NWCG Standard 

1	 A defined behavior, action, process, or equipment type, agreed upon by the National Wildfire 

Coordinating Group for wildland fire performance, and is necessary to meet consistent, 

interagency fire management activities. 

see also: National Wildfire Coordinating Group 

October 2014	 Page 128 
Glossary of Wildland Fire Terminology 

- O -

Objective 

1	 A description of a desired condition; quantified and measured, and where possible, with
 

established time frames for achievement. 

2	 Specific, achievable, measurable, time-limited results to be achieved through land management 

practices, either through a description of a desired condition or the degree of desired change in 

an attribute. 

Observation Time 

1	 Time of day required to record meteorological data at a fire danger station. 

Obstruction to Vision 

1	 Condition in which obscuring phenomenon restricts horizontal visibility to six statute miles (10 

km.) or less. 

Occluded Front or Occlusion 

1	 The front that is formed when and where a cold front overtakes a warm front or a stationary 

front. 

Occurrence Index (OI) 

1	 A number in the National Fire Danger Rating System related to potential fire incidence within a 

protection unit. 

Officer 

1	 The ICS title for personnel responsible for the Command Staff positions of Safety, Liaison, and 

Information. 

Off-road Vehicle (ORV) 

1 Any motorized vehicle designed for, or capable of, cross-country travel on or immediately over 

land, water, sand, snow, ice, marsh, swampland, or other terrain. 

synonym: All Terrain Vehicle 

Offshore Flow 

1	 Wind blowing from land to water. 

On-Call 

1	 Status of a federal casual or federal regular government employee used for timekeeping 

purposes. An employee is considered to be in on-call status (off shift-federal casuals and 

federal regular government employees) when he or she is allowed to leave a telephone number 

or to carry an electronic device for the purpose of being contacted, even though the employee is 

required to remain within a reasonable call-back radius and may include restrictions on alcohol 

consumption or use of certain medications. 5 CFR 551.431(b)(1) 

One Lick Method 

1	 A progressive system of building a fireline on a wildfire without changing relative positions in the 

line. Each worker does one to several "licks", or strokes, with a given tool and then moves 

forward a specified distance to make room for the worker behind. 

One-hour Timelag Fuel Moisture (1-h TL FM) 

1	 Moisture content of one-hour timelag fuels. 

October 2014	 Page 129 
 

 

Glossary of Wildland Fire Terminology 

One-hour Timelag Fuels 

1 Fuels consisting of dead herbaceous plants and roundwood less than about one-fourth inch (6.4 

mm) in diameter. Also included is the uppermost layer of needles or leaves on the forest floor. 

see also: One-hour Timelag Fuel Moisture 

One-hundred Hour Timelag Fuel Moisture (100-h TL FM) 

1	 The moisture content of the 100-hour timelag fuels. 

One-hundred Hour Timelag Fuels 

1	 Dead fuels consisting of roundwood in the size range of 1 to 3 inches (2.5 to 7.6 cm) in diameter 

and very roughly the layer of litter extending from approximately three-fourths of an inch (1.9 

cm) to 4 inches (10 cm) below the surface. 

see also: One-hour Timelag Fuel Moisture 

One-thousand Hour Timelag Fuel Moisture (1,000-h TL FM) 

1	 The moisture content of the 1,000-hour timelag fuels. 

One-thousand Hour Timelag Fuels 

1 Dead fuels consisting of roundwood 3-8 inches in diameter and the layer of the forest floor more 

than about 4 inches below the surface. 

see also: One-hour Timelag Fuel Moisture 

Onshore Flow 

1	 Wind blowing from water to land. 

Open Burning 

1	 Burning of any fuel outdoors without the use of mechanical combustion enhancements. 

Open Line 

1	 Refers to open fire front where no line has been constructed. 

Operating Weight 

1 For helicopters, the equipped weight plus weight of the crew and fuel. 

see also: Allowable Payload
 

Operational Control 

1	 The exercise of authority over initiating, conducting, or terminating any operation. Often
 

associated with aviation operations. 

Operational Period 

1	 The period of time scheduled for execution of a given set of tactical actions as specified in the 

Incident Action Plan. Operational Periods can be of various lengths, although usually not over 

24 hours. 

Operational Tempo 

1	 The speed and intensity of actions relative to the speed and intensity of the unfolding events in 

the operational environment. 

Operations Branch Director (OPBD) 

1 This ICS position is responsible for implementing that portion of an incident action plan (IAP) 

appropriate to a designated operational branch and reports to the Operations Section Chief. 

see also: Operations Section 

Operations Coordination Center (OCC) 

1	 Primary facility of the Multi-agency Coordination System (MACS); houses staff and equipment 

necessary to perform the MACS function. 

October 2014	 Page 130 
 

 

 

Glossary of Wildland Fire Terminology 

Operations Section 

1	 The section responsible for all tactical operations at the incident. Includes branches, divisions 

and/or groups, task forces, strike teams, single resources and staging areas. 

Operations Section Chief (OSC1 or OSC2) 

1	 This ICS position is responsible for supervising the Operations Section. Reports to the Incident 

Commander and is a member of the General Staff. This position may have one or more 

deputies assigned. 

see also: Operations Section 

Orbit 

1	 A circular holding pattern of an aircraft around a fixed location often related to a wildland fire. 

For example, the circular pattern of an air tanker in the vicinity of a wildland fire, waiting to make 

a retardant drop. 

Ordering Manager (ORDM) 

1 This ICS position is responsible for ordering personnel, equipment, and supplies for the incident 

and reports to the Supply Unit Leader. 

see also: Supply Unit 

Organic Matter 

1	 That fraction of the soil that includes plant and animal residues at various stages of 

decomposition, cells and tissues of soil organisms, and substances synthesized by the soil 

population. 

Organic Soil 

1	 Any soil or soil horizon containing at least 30% organic matter (e.g., muck, peat). 

Orographic 

1	 Pertaining to, or caused by mountains. 

Orthophoto 

1	 Photograph obtained from the orthogonal (i.e., horizontal) projection of a correctly oriented 

stereoscopic model formed by two overlapping aerial photographs; an orthophoto is free of tilt 

and relief displacements. 

Orthophoto Maps 

1	 Aerial photographs corrected to scale such that geographic measurements may be taken 

directly from prints. They may contain graphically emphasized geographic features and may be 

provided with overlays of such features as: water systems, facility location, etc. 

Osborne Firefinder 

1 A sighting device used by lookouts to determine the horizontal bearing and sometimes the
 

vertical angle of a fire from a lookout. 

synonym: Alidade
 

see also: Firefinder Map
 

Out-of-Service Resources 

1	 Resources assigned to an incident but unable to respond for mechanical, rest, or personal 

reasons. 

Outside Aid 

1	 Firefighting assistance given to adjacent areas and nearby communities by contract or other 

agreement that covers conditions and payment for assistance rendered and services performed. 

Contrasted to mutual aid, in which neighboring firefighting organizations assist each other 

without charge. 

October 2014	 Page 131 
Glossary of Wildland Fire Terminology 

Outside Diameter (OD) 

1	 External diameter of a cylinder or tube, conductor, or coupling as distinguished from the internal 

diameter. 

Overhaul 

1	 Fire department procedure of inspecting premises after extinguishment of fire, to insure that fire 

is completely out and unable to rekindle before returning control to owner or occupants. 

Overhead 

1	 Personnel assigned to supervisory positions, including incident commander, command staff, 

general staff, branch directors, supervisors, unit leaders, managers and staff. 

Overload 

1	 Gross vehicle weight (GVW) in excess of the gross vehicle weight rating (GVWR) specified by 

the chassis manufacturer. Also an excess of weight over the gross vehicle axle weight rating 

(GAWR) specified by the chassis manufacture. 

2	 A situation that taxes an operational system to the limit of its functional capabilities. Such as too 

many fires for an individual unit to handle (fire overload), or too many orders for an individual 

dispatch center to process (dispatch overload). 

Overwintering Fire 

1	 A fire that persists through the winter months until the beginning of fire season. 

Oxidation 

1	 Process during which oxygen combines with another substance. 

Oxidizer 

1	 The portion of a chemical mixture or compound which furnishes oxygen for burning a fuel or 

propellant, creating an oxide. 

- P -

Pack Test 

1	 Used to determine the aerobic capacity of fire suppression support personnel and assign
 

physical fitness scores. The test consists of walking a specified distance, with or without a 

weighted pack, in a predetermined period of time, with altitude corrections. 

Packing Ratio 

1	 The fraction of a fuel bed occupied by fuels, or the fuel volume divided by bed volume. 

Panoramic Photograph 

1	 Photographs from a lookout point, bearing azimuth and vertical angle scales, to assist in
 

locating fires with a firefinder. 

Panoramic Profile Map 

1	 A panoramic sketch drawn around the circumference of a firefinder map to show the profiles of 

the topography as it appears from the lookout. 

Paracargo 

1	 Anything intentionally dropped, or intended for dropping, from any aircraft by parachute, by other 

retarding devices, or by free fall. 

October 2014	 Page 132 
 

 

Glossary of Wildland Fire Terminology 

Parallel Attack 

1	 Method of fire suppression in which fireline is constructed approximately parallel to, and just far 

enough from the fire edge to enable workers and equipment to work effectively, though the 

fireline may be shortened by cutting across unburned fingers. The intervening strip of unburned 

fuel is normally burned out as the control line proceeds but may be allowed to burn out 

unassisted where this occurs without undue delay or threat to the fireline. 

Parallel Pumping 

1	 Procedure by which the flow from two fire pumps is combined into one hose line. 

Parallel Tandem Pumping 

1	 Procedure by which the flow from two fire pumps is combined into a third pump. 

Parameter 

1 A variable which can be measured quantitatively; sometimes, an arbitrary constant; associated 

with populations. One of the unknown values that determine a model. 

see also: Statistic 

Parking Tender 

1	 Person responsible to the deck coordinator for take-offs and landings of helicopters at an 

assigned touchdown pad. There is one parking tender for each touchdown pad. 

Partial Risk 

1	 Part of the National Fire Danger Rating System (NFDRS). Contribution of a specific source to 

human-caused risk, derived from the daily activity level assigned a risk source and its risk 

source ratio. 

Partial Risk Factor 

1	 Part of the National Fire Danger Rating System (NFDRS). Contribution to human-caused risk 

made by a specific risk source; a function of the daily activity level assigned that risk source and 

the appropriate risk source ratio. 

Partial-thickness Burn 

1	 A burn where the outer layer of skin is burned through and the second layer of skin (dermis) is 

damaged and is typically, a painful injury. Burns of this type cause reddening, blistering, and a 

mottled appearance. (also called Second Degree Burn) 

see also:	 Full-thickness Burn
 

Superficial Burn
 

Particle Size 

1	 The size of a piece of fuel, often expressed in terms of size classes. 

Particulate Matter 

1	 Any liquid or solid particles. "Total suspended particulates", as used in air quality, are those 

particles suspended in or falling through the atmosphere. They generally range in size 

(diameter) from 0.1 to 100 micrometers. 

Partners 

1	 All agencies and organizations that engage in joint decision making with federal agencies in 

planning and conducting fire management projects and activities. 

Parts of a Fire 

1	 Different areas of the fire usually determined by the predominant direction of fire spread and 

delineated from the fastest moving area (head) to the slowest moving area (base or tail). The 

most rapidly moving portion is designated the head of the fire, the adjoining portions of the 

perimeter at right angles to the head are known as the flanks, and the slowest moving portion is 

known as the rear or the base of the fire. 

October 2014	 Page 133 
 

 

Glossary of Wildland Fire Terminology 

Passive Crown Fire 

1	 A fire in the crowns of trees in which trees or groups of trees torch, ignited by the passing front 

of the fire. The torching trees reinforce the spread rate, but these fires are not basically different 

from surface fires. 

Patch Burning 

1	 Burning in patches to prepare sites for group planting or sowing or to form a barrier to 

subsequent fires.
 

Patrol 

1 To travel over a given route to prevent, detect, and suppress fires. Includes interaction with the 

public for wildland fire prevention and educational purposes. 

2 To go back and forth vigilantly over a length of control line during and/or after construction to 

prevent breakovers, suppress spot fires, and extinguish overlooked hot spots. 

3 A person or group of persons who carry out patrol actions. 

Patrol Time 

1	 Elapsed time from completion of original mopping up until the fire is declared to be
 

extinguished. 

Patrol Unit 

1	 Any light, mobile unit with limited pumping and water capacity. 

Pattern 

1	 The distribution of an aerially delivered retardant drop on the target area in terms of its length, 

width, and momentum (velocity x mass) as it approaches the ground. The latter determines the 

relative coverage level of the fire retardant on fuel within the pattern. 

synonym: Drop Pattern 

Pattern Clusters 

1	 A group of indicators in a close proximity, of the same or different categories, that exhibit
 

consistent directional values. 

Payload 

1	 Weight of passengers and/or cargo being carried by an aircraft. 

Peak Fire Season 

1	 That period of the fire season during which fires are expected to ignite most readily, to burn with 

greater than average intensity, and to create damages at an unacceptable level. 

Peak Monthly Average 

1	 Highest monthly average of human-caused fires calculated for a protection unit. 

Peak Wind 

1 The greatest 5-second average wind speed during the previous hour that exceeded 25 knots. 

Peak Wind Direction 

1	 Direction at Peak Wind Speed. 

Peak Wind Speed 

1	 Maximum wind speed during the previous 60 minutes. 

Percolation 

1	 Passage of liquid through a porous body, as movement of water through soil. 

October 2014	 Page 134 
Glossary of Wildland Fire Terminology 

Perennial Plant 

1 A plant that lives for more than two growing seasons. For fire danger rating purposes, biennial 

plants are classed with perennial plants. 

see also: Annual Plant 

Performance Chart 

1	 A chart, table, or graph provided by the manufacturer for use in determining an aspect of 

helicopter and fixed-wing aircraft performance. 

Performance Oriented Objectives 

1	 On-the-job performance enhancement is a result of online training. Performance oriented 

objectives or learning objectives for this training is developed, agreed to, and tested to ensure 

skill transfer. The purpose of learning objectives is to define the type of learning or performance 

outcomes that will occur at the conclusion of instruction and how learning will be assessed. Both 

objectives and performance outcomes should be written as precisely as possible in order to best 

determine whether they have been achieved. 

Perimeter Access 

1 Any road, trail, or route that will allow firefighting forces to reach the perimeter of a wildland fire. 

Period of Alert 

1	 Period of time when suppression crews, equipment, and aircraft are kept ready for deployment 

on short notice; usually employed when fire danger reaches a predetermined severity index. 

Permafrost 

1	 A short term for "permanently frozen ground"; any part of the earth's crust, bedrock, or soil
 

mantle that remains below 32° F (0° C) continuously for a number of years. 

Personal Protective Equipment (PPE) 

1	 That equipment and clothing required to mitigate the risk of injury from or exposure to 

hazardous conditions encountered during the performance of duty. PPE includes but is not 

limited to: fire resistant clothing, hard hat, flight helmets, shroud, goggles, gloves, respirators, 

hearing protection, chainsaw chaps, and shelter. 

Personnel Accountability 

1	 The ability to account for the location and welfare of personnel, accomplished when supervisors 

ensure that the ICS principles and processes are functional and personnel are working within 

these guidelines. 

Personnel Pool 

1	 Personnel who have reported to the incident without an assignment (i.e., they are not assigned 

to an increment, strike team, or organizational unit). 

Personnel Time Recorder 

1	 Person responsible to the time unit leader for daily recording of the time of all personnel at the 

incident, posting commissary charges to the time reports, closing out all records prior to 

personnel leaving the incident, and distributing completed time documents according to each 

agency's policy. 

Piling and Burning 

1	 Piling slash resulting from logging or fuel management activities and subsequently burning the 

individual piles. 

Pilot Balloon Operation (PIBAL) 

1	 A method of determining winds aloft by periodically reading the elevation and azimuth angles of 

a theodolite, usually at one-minute intervals, while tracking the ascent of a small free-lift balloon. 

A PIBAL is commonly used for constructing a wind profile. 

October 2014	 Page 135 
 

 

Glossary of Wildland Fire Terminology 

Pilotage 

1	 Navigation of aircraft by visual reference to landmarks. 

Pilot-in-Command 

1	 Pilot responsible for the operation and safety of an aircraft during flight time. 

Pin Lug Coupling 

1	 A hose coupling with one or more cylindrical studs on its outside rim. The studs allow the use of 

a spanner wrench to tighten the coupling. 

Pincer Action 

1	 Direct attack around a fire in opposite directions by two or more attack units. Usually conducted 

from the fire's tail to head. 

Ping-Pong Ball System 

1	 Mechanized method of dispensing DAIDs (Delayed Aerial Ignition Devices) at a selected rate. 

The DAIDs are polystyrene balls, 1.25 inches in diameter, containing potassium permanganate. 

The balls are fed into a dispenser, generally mounted in a helicopter, where they are injected 

with a water-glycol solution and then drop through a chute leading out of the helicopter. The 

chemicals react thermally and ignite in 25-30 seconds. The space between ignition points on 

the ground is primarily a function of helicopter speed, gear ratio of the dispenser, and the 

number of chutes used (up to four). 

see also:	 Aerial Ignition Device
 

Delayed Aerial Ignition Devices
 

Helitorch
 

Plastic Sphere Dispenser
 

Plan of Attack 

1	 The selected course of action and organization of personnel and equipment in fire suppression, 

as applied to a particular fire or to all fires of a specific type. 

Planetary Boundary Layer 

1	 That part of the earth's lower atmosphere that is directly influenced by the presence of the 

earth's surface and responds to surface forcings such as fronts, friction, evapotranspiration and 

convective mixing. 

Planned Ignition 

1 The intentional initiation of a wildland fire by management actions to meet specific objectives. 

see also: Prescribed Fire 

Planning Interval 

1	 Period of time between scheduled planning meetings. 

Planning Meeting 

1	 A meeting held regularly throughout the duration of an incident, to select specific strategies and 

tactics for incident control operations and to plan for needed service and support. On larger 

incidents, the planning meeting is a major element in the development of the Incident Action 

Plan. 

Planning Section 

1	 Responsible for the collection, evaluation, and dissemination of tactical information related to 

the incident, and for the preparation and documentation of incident action plans. The section 

also maintains information on the current and forecasted situation, and on the status of 

resources assigned to the incident. Includes the situation, resource, documentation, and 

demobilization units, as well as technical specialists. 

October 2014	 Page 136 
 

Glossary of Wildland Fire Terminology 

Planning Section Chief (PSC1 or PSC2) 

1	 This ICS position is responsible for supervising the Planning Section. Reports to the Incident 

Commander and is a member of the General Staff. This position may have one or more 

deputies assigned. 

see also:	 Planning Section 

Plastic Sphere Dispenser (PSD) 

1	 Device installed, but jettisonable, in a helicopter, which injects glycol into a plastic sphere 

containing potassium permanganate, which is then expelled from the machine and aircraft. This 

produces an exothermic reaction resulting in ignition of fuels on the ground for prescribed or 

wildland fire applications. 

see also:	 Aerial Ignition Device
 

Delayed Aerial Ignition Devices
 

Helitorch
 

Ping-Pong Ball System
 

Plow Line 

1 Fireline constructed by a fire plow, usually drawn by a tractor or other motorized equipment. 

see also:	 Dozer
 

Dozer Line
 

Tractor
 

Tractor Plow
 

Plume 

1 A convection column generated by combustion (of wildland fuel). 

see also: Convection Column
 

Plume Rise 

1	 How high above the level of release an emission plume rises. 

Plume-dominated Wildland Fire 

1	 A wildland fire whose activity is determined by the convection column. 

PM10 (PM10) 

1	 Particulate matter of mass median aerodynamic diameter (MMAD) less than or equal to 10 

micrometers. 

PM2.5 (PM2.5) 

1	 Particulate matter of mass median aerodynamic diameter (MMAD) less than or equal to 2.5 

micrometers. 

Pockets of a Fire 

1	 Unburned indentations in the fire edge formed by fingers or slow burning areas. 

Point of Attack 

1	 That part of the fire on which work is started when suppression crews arrive. 

Point of Origin 

1	 The location where a competent ignition source came into contact with the material first ignited 

and sustained combustion occurred. 

Point Source 

1	 A permanent source of air pollution that can be distinctly identified such as a smokestack. 

October 2014	 Page 137 
Glossary of Wildland Fire Terminology 

Point Source Fire Predictions 

1	 Predictions that apply to an initiating fire burning during a time when conditions have been 

relatively constant, or where it can be assumed that the fire will maintain a basically elliptical 

shape. 

Poise 

1	 Unit of fluid viscosity in fire retardant, defined as tangential force per unit area (dynes/square 

centimeter) required to maintain unit difference in velocity (1 centimeter/second) between two 

parallel planes separated by 1 cm of fluid (1 poise=1 dyne-second/cubic centimeter). 

Portable Pump 

1	 Small gasoline-driven pump that can be carried to a water source by one or two firefighters or 

other conveyance over difficult terrain. 

Portatank 

1	 Container, either with rigid frame or self supporting, which can be filled with water or fire 

chemical mixture from which fire suppression resources can be filled. It can also be a source for 

charging hose lays from portable pumps or stationary engines. 

Position Currency Requirement 

1	 The requirement to perform satisfactorily in a specified position within the last five years (three 

years for aviation and expanded dispatch positions) in order to maintain qualification for the 

position. 

Position Performance Assignment 

1 An assignment in which an individual is being evaluated for tasks found in the position task 

book. 

see also: Position Task Book 

Position Task Book (PTB) 

1	 A document listing the performance requirements (competencies and behaviors) for a position 

in a format that allows for the evaluation of individual (trainee) performance to determine if an 

individual is qualified in the position. Successful performance of PTB tasks, as observed and 

recorded by a qualified evaluator, will result in a recommendation to the trainee's home unit that 

the individual be certified in the position. 

see also:	 Agency Certification
 

Behavior
 

Competency
 

Evaluator
 

Home Unit
 

Trainee
 

Positive Displacement Pump 

1	 A pump which moves a specified quantity of water through the pump chamber with each stroke 

or cycle; it is capable of pumping air, and therefore is self-priming, but must have pressure relief 

provisions if plumbing or hoses have shut-off nozzles or valves . Gear pumps and piston pumps 

are common examples of this type. 

Potato Roll 

1	 Quick method of rolling hose for pick up; hose is rolled as a ball of string. 

Pounds per Square Inch (PSI) 

1	 Measurement of pressure (e.g., pump pressure, nozzle pressure, friction loss in hose, pressure 

loss or gain due to elevation). 

October 2014	 Page 138 
 

 

 

Glossary of Wildland Fire Terminology 

Preattack 

1	 A planned, systematic procedure for collecting, recording, and evaluating prefire and fire 

management intelligence data for a given planning unit or preattack block. The planning phase 

is usually followed by a construction and development program integrated with other resources 

and activities. 

Preattack Block 

1 Unit of wildland delineated by logical and strategic topographic features for preattack planning. 

Preattack Planning 

1	 Within designated blocks of land, planning the locations of firelines, fire camps, water sources, 

and helispots; planning transportation systems, probable rates of travel, and constraints of travel 

on various types of attack units; and determining what types of attack units likely would be 

needed to construct particular firelines, their probable rate of fireline construction, and 

topographic constraints on fireline construction. 

Precautionary Landing 

1	 A landing necessitated by apparent impending failure of engines, systems, or components 

which makes continued flight unadvisable. 

Precipitation 

1	 Any or all forms of water particles, liquid or solid, that fall from the atmosphere and reach the 

ground. 

Precipitation Amount 

1	 The total amount of precipitation that occurred within the preceding 24-hour period. 

Precipitation Duration 

1	 Time, in hours and fraction of hours, that a precipitation event lasts. More precisely, for fire 

danger rating purposes, the length of time that fuels are subjected to liquid water. 

Precipitation Gauge 

1	 Device commonly used to collect and permit measurement of any form of rain and snow
 

sufficiently heavy to have fallen to the earth's surface. Also called rain gauge. 

Precision Approach Procedure 

1	 A standard instrument approach procedure for fixed-wing aircraft in which an electronic glide 

slope is provided, such as ILS and PAR. 

Precision Approach Radar (PAR) 

1	 Blind landing in which the aircraft is observed from the ground by means of radar and directed 

along a suitable glide path by instructions radioed to the pilot. 

Preconnected 

1	 Hard suction hose or discharge hose carried connected to pump, eliminating delay occasioned 

when hose and nozzles must be connected and attached at fire. 

Predictive Services 

1	 Those Geographic Area and National-level fire weather or fire danger services and products 

produced by wildland fire agency meteorologists and intelligence staffs in support of resource 

allocation and prioritization. 

Pre-Green 

1 In the 1978 version of NFDRS, the herbaceous stage approximately 30 days prior to green-up. 

October 2014	 Page 139 
Glossary of Wildland Fire Terminology 

Preignition Combustion Phase 

1	 Thermal or chemical decomposition of fuel at an elevated temperature. This is the precombustion stage of burning during which distillation and pyrolysis predominate. Heat energy is 

absorbed by the fuel which, in turn, gives off water vapor and flammable tars, pitches, and 

gases. These ignite when mixed with oxygen to initiate the flaming combustion phase. 

Preignition Phase 

1	 Preliminary phase of combustion in which fuel elements ahead of the fire are heated, causing 

fuels to dry. Heat induces decomposition of some components of the wood, causing release of 

combustible organic gases and vapors. 

Preparedness 

1 Activities that lead to a safe, efficient, and cost-effective fire management program in support of 

land and resource management objectives through appropriate planning and coordination. 

2 Mental readiness to recognize changes in fire danger and act promptly when action is 

appropriate. 

3 The range of deliberate, critical tasks, and activities necessary to build, sustain, and improve the 

capability to protect against, respond to, and recover from domestic incidents. 

see also: Readiness 

Preparedness Plan 

1	 A written plan providing for timely recognition of approaching critical fire situations, priority 

setting, the deployment of forces, and other actions to respond to those situations. 

Prescribed Burning 

1	 Application of prescribed fire. 

Prescribed Fire 

1 Any fire intentionally ignited by management actions in accordance with applicable laws, 

policies, and regulations to meet specific objectives. 

see also: Wildfire
 

Wildland Fire
 

Prescribed Fire Burn Plan 

1	 A plan required for each fire application ignited by management. Plans are documents prepared 

by qualified personnel, approved by the agency administrator, and include criteria for the 

conditions under which the fire will be conducted (a prescription). Plan content varies among the 

agencies. 

synonym: Prescribed Fire Plan
 

see also: Implementation Plan
 

Prescribed Fire Module 

1 A team of skilled and mobile personnel dedicated primarily to prescribed fire management that 

can ignite, hold and monitor prescribed fires. 

see also: Wildland Fire Module 

Prescribed Fire Plan 

1	 A plan for each prescribed fire, prepared by qualified personnel, approved by the agency 

administrator, which includes criteria for the conditions under which the fire will be conducted (a 

prescription). 

synonym: Prescribed Fire Burn Plan 

October 2014	 Page 140 
Glossary of Wildland Fire Terminology 

Prescription 

1	 In the context of wildland fire, a prescription is measurable criteria that define conditions under 

which a prescribed fire may be ignited. Prescriptions may also be used to guide selection of 

management responses to wildfire to define conditions under which management actions are 

most likely to achieve incident management objectives. Prescription criteria typically describe 

environmental conditions such as temperature, humidity and fuel moisture, but may also include 

safety, economic, public health, geographic, administrative, social, or legal considerations. 

Pressure Gradient 

1	 The difference in atmospheric pressure between two points on a weather map. That is, the 

magnitude of pressure difference between two points at sea level, or at constant elevation 

above sea level. Wind speed is directly related to pressure gradient. If distance between 

constant pressure lines is reduced by one-half, wind speed will be doubled. Conversely, if 

distance between lines is doubled, wind speed will be reduced by one-half. 

Pressure Loss 

1	 Reduction in water pressure between a pump or hydrant and a nozzle due to expenditure of 

pressure energy required to move water through a hose; includes losses due to back pressure, 

friction loss, elevation loss, and/or losses in fittings. 

Pressure Pattern 

1	 The distribution of surface atmospheric pressure features over an area of the earth as shown on 

a weather map. Surface pressure features include lines of constant pressure (isobars), highs, 

lows, and pressure gradient. The pressure pattern is directly related to wind speeds and 

directions at specific locations. 

Presuppression 

1	 Activities in advance of fire occurrence to ensure effective suppression action. Includes planning 

the organization, recruiting and training, procuring equipment and supplies, maintaining fire 

equipment and fire control improvements, and negotiating cooperative and/or mutual aid 

agreements. 

Pretreat 

1	 The use of water, foam or retardant along a control line in advance of the fire. Often used
 

where ground cover or terrain is considered best for control action. 

Prevention 

1	 Activities directed at reducing the incidence of fires, including public education, law
 

enforcement, personal contact, and reduction of fuel hazards (fuels management). 

2	 Actions to avoid an incident, to intervene for the purpose of stopping an incident from occurring, 

or to mitigate an incident's effect to protect life and property. Includes measures designed to 

mitigate damage by reducing or eliminating risks to persons or property, lessening the potential 

effects or consequences of an incident. 

see also: Fire Education 

Prevention of Significant Deterioration (PSD) 

1	 A program identified by the Clean Air Act to prevent air quality and visibility degradation and to 

remedy existing visibility problems. Areas of the country are grouped into 3 classes which are 

allowed certain degrees of pollution depending on their uses. National Parks and Wilderness 

Areas meeting certain criteria are "Class I" or "clean area" in that they have the smallest 

allowable increment of degradation. 

Primary Lookout 

1	 A lookout point that must be staffed to meet planned minimum seen area coverage in a given 

locality. For that reason, continuous service is necessary during the normal fire season and the 

lookout (person) is not sent to fires. 

October 2014	 Page 141 
 

 

 

Glossary of Wildland Fire Terminology 

Priming 

1	 Filling pump with water when pump is taking water not under a pressure head. Necessary for 

centrifugal pumps. 

Probability 

1	 A number representing the chance that a given event will occur. The range is from 0% for an 

impossible event, to 100% for an inevitable event. 

Probability Forecast 

1	 A forecast of the probability of occurrence of one or more of a mutually exclusive set of weather 

contingencies as distinguished from a series of categorical statements. 

Probability of Ignition 

1	 The chance that a firebrand will cause an ignition when it lands on receptive fuels. 

Procurement Unit 

1	 Functional unit within the Finance/Administration Section responsible for managing all financial 

matters pertaining to vendor contracts. 

Procurement Unit Leader (PROC) 

1 The ICS position responsible for supervising the Procurement Unit. Reports to the
 

Finance/Administration Section Chief. 

see also: Procurement Unit
 

Progressive Hose Lay 

1	 A hose lay in which double shutoff wye (Y) valves are inserted in the main line at intervals and 

lateral lines are run from the wyes to the fire edge, thus permitting continuous application of 

water during extension of the lay. 

Progressive Method of Line Construction 

1	 A system of organizing workers to build fireline in which they advance without changing relative 

positions in line. 

Project Activity Level (PAL) 

1	 An application of fire danger rating to support regulation of contractors involved in land 

management activities for fire prevention purposes in California. 

Project Objectives 

1	 The specific results expected from completing a project. 

Proportioner 

1	 A device that adds a predetermined amount of foam concentrate to water to form foam solution. 

Protecting Agency 

1	 Agency responsible for providing direct incident management within a specific geographical 

area pursuant to its jurisdictional responsibility or as specified and provide by contract, 

cooperative agreement, etc. 

see also:	 Fire Agency
 

Responsible Fire Agency
 

Protection 

1	 The actions taken to mitigate the adverse effects of fire on environmental, social, political,
 

economic, and community values at risk. 

October 2014	 Page 142 
 

 

Glossary of Wildland Fire Terminology 

Protection Area 

1	 That area for which a particular fire protection organization has the primary responsibility for 

attacking an uncontrolled fire and for directing the suppression action. Such responsibility may 

develop through law, contract, or personal interest of the firefighting agent (e.g., a lumber 

operator). Several agencies or entities may have some basic responsibilities (e.g., private 

owner) without being known as the fire organization having direct protection responsibility. 

synonym: Direct Protection Area 

Protection Boundary 

1	 The exterior perimeter of an area within which a specified fire agency has assumed a degree of 

responsibility for wildland fire control. It may include land in addition to that for which the agency 

has jurisdiction or contractual responsibility. 

Protection Indicators 

1	 Fuels that are unburned or exhibit a less damaged appearance on the non-origin side of the fuel 

itself or other objects. 

Protection Unit 

1	 A geographical area which is administratively defined and which is the smallest area for which 

organized fire suppression activities are formally planned. 

Psychrometer 

1	 General name for instruments designed to determine the moisture content of air. A 

psychrometer consists of dry- and wet-bulb thermometers that give the dry- and wet-bulb
 

temperatures, which in turn are used to determine relative humidity and dew point. 

Public Aircraft 

1	 Aircraft used only in the service of a government or a political subdivision. It does not include 

any government-owned aircraft engaged in carrying persons for commercial purposes. 

Public Information Officer (PIO1, PIO2, PIOF) 

1	 This ICS position is responsible for developing and releasing information about the incident to 

the news media, incident personnel, and to other appropriate agencies and organizations. 

Reports to the Incident Commander and is a member of the Command Staff. This position may 

have one or more assistants assigned. 

Pulaski 

1	 A combination chopping and trenching tool widely used in fireline construction, which combines 

a single-bitted axe blade with a narrow adze-like trenching blade fitted to a straight handle. 

Punky Material 

1	 Partly decayed material, such as old wood, in which fire can smolder unless it is carefully 

mopped up and extinguished. A good receptor for firebrands when dry. 

Pyrolysis 

1	 The thermal or chemical decomposition of fuel at an elevated temperature. This is the 

preignition combustion phase of burning during which heat energy is absorbed by the fuel 

which, in turn, gives off flammable tars, pitches, and gases. 

Pyrotechnic 

1	 A mixture of chemicals designed to produce heat, light, gas, smoke or noise. 

October 2014	 Page 143 
 

 

Glossary of Wildland Fire Terminology 

- Q -

Quadrangle 

1	 Mapping unit which defines an area in terms of longitude and latitude distance. Two common 

scales are 1:24,000 quadrangles, which are 7.5' longitude x 7.5' latitude, and 1:62,500 

quadrangles, which are 15' longitude x 15' latitude. 

Qualification Sheet 

1	 A written resume of an expert witness used to show that expert’s sufficient special expertise in 

the field. 

Qualifications and Certification 

1	 This subsystem of NIIMS provides recommended qualification and certification for those 

personnel responding to an incident regionally or nationally, allowing for the development of 

local minimum standards to meet local needs. Standards typically include training, experience, 

and physical fitness. 

see also: National Interagency Incident Management System 

- R -

Radial 

1	 A magnetic bearing extending from a ground-based navigational system, providing airborne 

navigation information. 

Radiant Burn 

1	 A thermal trauma that maybe a superficial, partial thickness or full thickness burn. 

Radiant Heat Flux 

1	 The amount of heat flowing through a given area in a given time, usually expressed as
 

calories/square centimeter/second. 

Radiation 

1 Propagation of energy in free space by virtue of joint, undulatory variations in the electric or 

magnetic fields in space, (i.e., by electromagnetic waves). 

2 Transfer of heat in straight lines through a gas or vacuum other than by heating of the 

intervening space. 

Radio Cache 

1	 A cache may consist of a number of portable radios, base station, and, in some caches, a radio 

repeater that is stored in a predetermined location for dispatch to incidents. 

Radio Fix 

1	 Determination of position by one or more radio navigational aids. 

Radiosonde 

1	 A device carried aloft by a balloon equipped with measuring instruments that automatically 

convert temperature, pressure, and humidity data into electrical impulses and transmit this 

information to a ground recorder. 

see also: Sounding (Upper Air Sounding) 

Railroad Fire 

1	 A fire resulting from any operation or activity of a railroad, except smoking. 

October 2014	 Page 144 
 

Glossary of Wildland Fire Terminology 

Range Fire 

1	 Any wildfire on rangeland. 

Ranger District 

1	 An administrative subdivision of a national forest (under a district ranger) or other tract of public 

land. 

Rappelling 

1	 Technique of landing specifically trained and certified firefighters from hovering helicopters; 

involves sliding down ropes with the aid of friction-producing devices. 

Rate of Spread 

1	 The relative activity of a fire in extending its horizontal dimensions. It is expressed as rate of 

increase of the total perimeter of the fire, as rate of forward spread of the fire front, or as rate of 

increase in area, depending on the intended use of the information. Usually it is expressed in 

chains or acres per hour for a specific period in the fire's history. 

see also: Forward Rate of Spread 

Rate of Spread Factor 

1	 A factor usually on a scale of 1 to 100 which represents a relative rate of forward spread for a 

specific fuel condition and fixed weather conditions (or fuel model). Factors can be used as 

multipliers, arguments for entering tables, or provide a ratio of values between two fuels. 

Rate of Spread Meter 

1	 A device that computes the probable rate of spread of a fire for different combinations of fuel 

moisture, wind speed, and other selected factors. 

Rating Period 

1	 Part of the National Fire Danger Rating System (NFDRS). The period of time during which a fire 

danger rating value is considered valid or representative for administrative or other purposes. 

Normally it is 24 hours extending from midnight to midnight. 

Rawinsonde 

1	 Method of upper-air observation consisting of an evaluation of the wind speed and wind 

direction, temperature, pressure, and relative humidity aloft by means of a balloon-borne
 

radiosonde tracked by a radar or radio direction-finder. 

Reaction Intensity 

1 The rate of heat release, per unit area of the flaming fire front, expressed as heat 

energy/area/time, such as Btu/square foot/minute, or Kcal/square meter/second. 

see also: Combustion Rate
 

Readiness 

1 Condition or degree of being completely ready to cope with a potential fire situation. 

2 Mental readiness to recognize changes in fire danger and act promptly when action is
 

appropriate. 

see also: Preparedness
 

Rear (Of a Fire) 

1 That portion of a fire spreading directly into the wind or down slope. 

2 That portion of a fire edge opposite the head. 

3 Slowest spreading portion of a fire edge. Also called heel of a fire. 

October 2014	 Page 145 
 

 

Glossary of Wildland Fire Terminology 

Reasonably Available Control Measures (RACM) 

1	 Control measures developed by EPA which apply to residential wood combustion, fugitive dust, 

and prescribed and silvicultural burning in and around "moderate" PM-10 non-attainment areas. 

RACM is designed to bring an area back into attainment and uses a smoke management 

program which relies on weather forecasts for burn/no-burn days. 

see also: Best Available Control Measures 

Reburn 

1 Repeat burning of an area over which a fire has previously passed, but left fuel that later ignites 

when burning conditions are more favorable. 

2 An area that has reburned. 

Receiving and Distribution Manager (RCDM) 

1 This ICS position is responsible for receiving and distributing supplies and equipment ordered 

for the incident and reports to the Supply Unit Leader. 

see also: Supply Unit 

Re-Certification 

1	 Confirmation through the re-issuance of an incident qualification card that an individual has 

regained qualifications for a specified position that was lost through a lack of current experience. 

A key component in the certification or re-certification process is the subjective evaluation by the 

appropriate agency official of an individual's capability to perform in a position. 

Reconnaissance (RECON) 

1	 To examine a fire area to obtain information about current and probable fire behavior and other 

related fire suppression information. 

Recorders 

1	 Individuals within ICS organizational units who are responsible for recording information. 

Recorders may be found in planning, logistics and finance/administration units. 

Recovery 

1 The increase in fuel moisture as a result of increased relative humidity, usually occurring 

overnight. 

2 The general term used to describe the maximum overnight value of atmospheric relative 

humidity.
 

Recreation Fire 

1	 A fire resulting from recreational use, except smoking. 

Recurrent Training 

1	 Training scheduled at established intervals that has been identified as required training in order 

to maintain position currency. 

Red Flag Warning 

1 Term used by fire weather forecasters to alert forecast users to an ongoing or imminent critical 

fire weather pattern. 

see also: Fire Weather Watch 

Reel 

1	 A frame on which hose is wound, now chiefly used for "booster" or small hose (3/4- or l-inch 

hose) (19 or 25 mm) supplied by a water tank on the apparatus; also, a hand-drawn 2-wheel 

frame for 2-1/2 inch (64 mm) hose used in industrial plants. 

October 2014	 Page 146 
 

 

 

 

Glossary of Wildland Fire Terminology 

Regional Haze 

1 Visibility impairment caused by the cumulative air pollutant emissions from numerous sources 

over a wide geographic area. 

see also: Haze 

Rehabilitation 

1	 Efforts undertaken within three years of a wildland fire to repair or improve fire damaged lands 

unlikely to recover to a management approved conditions or to repair or replace minor facilities 

damaged by fire. 

see also: Burned Area Rehabilitation 

Rekindle 

1	 Reignition due to latent heat, sparks, or embers or due to presence of smoke or steam. 

Relative Greenness (RG) 

1 An NDVI-derived image of vegetation greenness compared to how green it has been
 

historically. 

see also: Greenness Factor
 

Relative Humidity (RH) 

1	 The ratio of the amount of moisture in the air, to the maximum amount of moisture that air would 

contain if it were saturated. The ratio of the actual vapor pressure to the saturated vapor 

pressure. 

Relay 

1	 Use of two or more fire pumps to move water a distance which would require excessive 

pressures in order to overcome friction loss if only one pump were employed at the source. 

Relay Tank 

1	 A tank, usually collapsible, used as a reservoir in the relay of water from one fire pump to 

another. 

Release Order 

1	 The order that defines when personnel and/or equipment will be ready for release from an
 

incident. 

Relief Valve 

1	 A pressure-controlled device which bypasses water at a fire pump to prevent excessive
 

pressures when a nozzle is shut down. 

Reload Base 

1 An airfield where air tankers are reloaded but not permanently stationed. 

see also: Air Attack Base
 

Remote Automatic Weather Station (RAWS) 

1	 A weather station that transmits weather observations via GOES satellite to the Wildland Fire 

Management Information system. 

Repeater 

1	 A radio signal station that automatically relays a radio transmission, sometimes over a different 

frequency, thereby increasing the range of transmission. Repeaters are often named for the 

mountaintops or peaks where they are installed. 

Report Time 

1	 Elapsed time from fire discovery until the first personnel charged with initiating action for fire 

suppression are notified of its existence and location. 

October 2014	 Page 147 
 

 

 

 

Glossary of Wildland Fire Terminology 

Reportable Fire 

1	 Any wildfire that requires fire suppression to protect natural resources or values associated with 

natural resources, or is destructive to natural resources. 

Reporting Locations 

1	 Location or facilities where incoming resources can check-in at the incident. Check-in locations 

include: incident command post (resources unit), incident base, camps, staging areas, 

helibases, helispots, and direct to the line. Check-in at one location only. 

see also: Check-in 

Required Experience 

1	 Documented, satisfactory performance in a specified position needed to qualify for another 

(usually higher level) position. Required experience cannot be challenged. 

Required Training 

1	 A course or courses that must be completed prior to initiating a position task book. Training 

which has been identified as required cannot be challenged; an agency equivalent course may 

be used as a substitute when the course meets or exceeds a required course's learning and 

performance objectives. 

Rescue 

1	 Saving a life from fire or accident; removing a victim from an untenable or unhealthy
 

atmosphere. 

Rescue Medical 

1	 Any staffed ground vehicle capable of providing medical services. 

Rescue Medical Vehicle 

1	 Any staffed ground vehicle capable of providing emergency medical care and staffed with
 

appropriate number of trained personnel and equipment for that incident.
 

Reserve 

1	 In wildland fire suppression terminology resources not assigned to a specific task, but available 

for assignment. 

Residence Time 

1	 The time, in seconds, required for the flaming front of a fire to pass a stationary point at the 

surface of the fuel. The total length of time that the flaming front of the fire occupies one point. 

Residual Combustion Stage 

1	 The smoldering zone behind the zone of an advancing fire front. 

Residual Smoke 

1	 Smoke produced by smoldering material. The flux of smoke originating well after the active 

flaming combustion period with little or no vertical buoyancy and, therefore, most susceptible to 

subsidence inversions and down-valley flows. 

Resistance to Control 

1	 The relative difficulty of constructing and holding a control line as affected by resistance to line 

construction and by fire behavior. Also called difficulty of control. 

Resistance to Line Construction 

1	 The relative difficulty of constructing control line as determined by the fuel, topography, and 

soil. 

October 2014	 Page 148 
Glossary of Wildland Fire Terminology 

Resource Capability 

1	 The ability of the wildland fire program to respond to current and anticipated workload needs for 

the area of concern. 

Resource Order 

1	 The form used by dispatchers, service personnel, and logistics coordinators to document the 

request, ordering or release of resources, and the tracking of those resources on an incident. 

Resource Ordering and Status System (ROSS) 

1	 A national system that provides automated support to interagency and agency dispatch and 

coordination offices. The system will provide current status of resources available to support allrisk activities; enable dispatch offices to exchange and track resource ordering information 

electronically; enable dispatch offices to rapidly and reliably exchange mission-critical 

emergency electronic messages. 

Resource Status Board 

1	 Visual aid containing pertinent information regarding fire organization, current operational period 

resources, previous operational period resources, and next operational period resources being 

prepared; placed at a convenient location in fire camp for review by fireline overhead personnel 

on large fires. 

Resource Use Specialist 

1	 Person responsible to the planning section chief for determining capabilities and limitations of 

resources at an incident. 

Resource Value-at-risk 

1	 Fire suppression planning tool providing a relative expression (in five classes) of fire effects on 

all resources (not the value of the resources themselves). 

Resources 

1	 Personnel, equipment, services and supplies available, or potentially available, for assignment 

to incidents. Personnel and equipment are described by kind and type, e.g., ground, water, air, 

etc., and may be used in tactical, support or overhead capacities at an incident. 

2	 The natural resources of an area, such as timber, grass, watershed values, recreation values, 

and wildlife habitat. 

see also:	 Active Resources
 

Allocated Resources
 

Assigned Resources
 

Available Resources
 

Values To Be Protected
 

Values-At-Risk
 

Resources Unit 

1	 Functional unit within the planning section responsible for recording the status of resources 

committed to the incident. The unit also evaluates resources currently committed to the incident, 

the impact that additional responding resources will have on the incident, and anticipated 

resource needs. 

Resources Unit Leader (RESL) 

1 The ICS responsible for supervising the Resources Unit. Reports to the Planning Section Chief. 

see also: Resources Unit 

October 2014	 Page 149 
 

 

Glossary of Wildland Fire Terminology 

Respirator 

1	 A simple filter mask for individual protection against smoke and fumes, recommended for use in 

fire suppression on wildfires only; not recommended for use on structure fires or fires involving 

most hazardous materials. 

see also:	 Air Pack
 

Self-Contained Breathing Apparatus
 

Responsible Fire Agency 

1 Agency with primary responsibility for fire suppression on any particular land area.
 

see also: Fire Agency
 

Responsible Fire Agency
 

Restoration 

1	 The continuation of rehabilitation beyond the initial three years or the repair or replacement of 

major facilities damaged by the fire. 

Restricted Airspace 

1	 Airspace of defined dimensions identified by an area on the surface of the earth within the flight 

of an aircraft, which is subject to restrictions (but not wholly prohibited). 

Restricted Category 

1	 Aircraft that is generally used for cargo, retardant dropping, agricultural operations, survey work 

and other specific projects, and may not transport passengers. 

Restrictions 

1	 Measures taken by jurisdictional agencies to impose bans and standards of use on certain 

human activities that could lead to the cause of wildland fire. Restrictions may be applied to: 

smoking in designated areas; open flame; mechanical operations in high-risk areas; and offroad use. 

see also:	 Closure 

Retardant 

1	 A substance or chemical agent which reduces the flammability of combustibles. 

Retardant Base 

1	 Ground facilities for mixing, storing, and loading fire retardant into air tankers. 

Retardant Coverage 

1	 Area of fuel covered and degree of coverage on the fuel by a fire retardant, usually expressed in 

terms of gallons per hundred square feet (liters per square meter). 

Retardant Drop 

1	 Fire retardant cascaded from an air tanker or helitanker. 

Return and Hold 

1	 An order to an air tanker pilot to return to the retardant base and await further instructions; 

mission completed, further loads not required. 

Reversible Siamese (SIMWYE) 

1 Hose fitting that performs the functions of a Siamese or a wye (i.e., to combine the flow from two 

lines into a single line or to permit two lines to be taken from a single line). 

see also: Siamese 

Wye 

Rheologic Properties 

1	 Flow characteristics of liquid fire retardants, especially their cohesiveness or ability to hold
 

together while falling through the air. 

October 2014	 Page 150 
 

Glossary of Wildland Fire Terminology 

Rheology 

1	 Science of deformation and flow of fire retardants and other liquids, especially of the
 

cohesiveness bodies and stress-strain relationship of their particles.
 

Rich Tool 

1	 A long-handled combination rake and cutting tool, the blade of which is constructed of a single 

row of mowing machine cutter teeth fastened to a piece of angle iron. Also called fire rake or 

council rake. 

see also: Council Tool 

Ridge 

1 An elongated area of relatively high atmospheric pressure extending from the center of a highpressure region. 

see also: Surface High 

Ring Fire 

1	 A fire started by igniting the full perimeter of the intended burn area so that the ensuing fire 

fronts converge toward the center of the burn. Set around the outer perimeter of a resource to 

establish a protective black-line-buffer. 

Risk 

1 The chance of fire starting as determined by the presence and activity of causative agents. 

2 A chance of suffering harm or loss. 

3 A causative agent. 

4 (NFDRS) A number related to the potential of firebrands to which a given area will be exposed 

during the rating day. 

Risk Index 

1	 A number related to the probability of a firebrand igniting a fire. 

Risk Management (RM) 

1	 A continuous, five-step process that provides a systematic method for identifying and managing 

the risks associated with any operation. 

Risk Source 

1	 Identifiable human activity that historically has been a major cause of wildfires on a protection 

unit; one of the eight general causes listed on the standard fire report. 

Risk Source Ratio 

1	 Portion of human-caused fires that have occurred on a protection unit chargeable to a specific 

risk source; calculated for each day of the week for each risk source. 

Rocker Lug Coupling 

1	 Hose coupling in which the lugs used for tightening or loosening are semicircular in shape and 

designed to pass over obstructions. 

Roll Cloud 

1	 A turbulent altocumulus-type cloud formation found in the lee of some large mountain barriers. 

The air in the cloud rotates around an axis parallel to the range. Also sometimes refers to part of 

the cloud base along the leading edge of a cumulonimbus cloud; it is formed by rolling action in 

the wind shear region between cool downdrafts within the cloud and warm updrafts outside the 

cloud. Also called rotor cloud. 

Rotor 

1	 Assembly of airfoils (rotor blades), together with a hub and attachments, that rotates about an 

axis to provide lift and/or thrust on a helicopter. 

October 2014	 Page 151 
Glossary of Wildland Fire Terminology 

Rotor Blast 

1	 Air turbulence occurring under and around the main rotor of an operating helicopter. Also called 

rotor downwash. 

Rotor Diameter 

1	 The main rotor arc in feet and inches (meters). Used for planning helispot clearance. 

Rotorcraft 

1 An aircraft that depends principally on the lift generated by one or more rotors for its support in 

flight. Also called rotary wing. 

synonym: Helicopter 

Rough 

1	 The accumulation of living and dead ground and understory vegetation, especially grasses, 

forest litter, and draped dead needles, sometimes with addition of underbrush such as palmetto, 

gallberry, and wax myrtle. Most often used for southern pine types. 

Rough Reduction 

1	 Reduction of fire hazard in rough, usually by prescribed burning. 

Route Card 

1	 Index card used by a dispatcher and frequently carried on fire apparatus which lists specific 

directions for responding to individual rural properties. The card frequently includes a 

description of the property, water sources available, and any special information pertinent to fire 

suppression and rescue operations. Also called running card. 

Run (Of a Fire) 

1	 Rapid advance of the head of a fire, characterized by a marked transition in fireline intensity and 

rate of spread with respect to that noted before and after the advance. 

Running Fire 

1	 Behavior of a fire spreading rapidly with a well defined head. 

Rural 

1	 Any area wherein residences and other developments are scattered and intermingled with
 

forest, range, or farm land and native vegetation or cultivated crops. 

Rural Fire District (RFD) 

1	 An organization established to provide fire protection to a designated geographic area outside of 

areas under municipal fire protection. Usually has some taxing authority and officials may be 

appointed or elected. 

Rural Fire Protection 

1	 Fire protection and firefighting problems that are outside of areas under municipal fire 

prevention and building regulations and that are usually remote from public water supplies. 

- S -

Saddle 

1	 Depression or pass in a ridgeline. 

SAFENET (SAFENET) 

1	 A form and process, used by wildland firefighting agencies, for reporting and resolving incidents 

relating to firefighter safety. The information collected is used to determine long-term trends and 

problem areas within the wildland fire industry. 

October 2014	 Page 152 
 

 

 

Glossary of Wildland Fire Terminology 

Safety Advisory 

1 A safety alert addressing wildland fire safety information that isn't related to imminent or
 

potential threats of injury. 

see also: Safety Alert
 

Safety Alert 

1	 A warning or alert concerning critical information relating to firefighter safety, that is distributed 

via email through an NWCG mail server. There are three types of alerts: Safety Warning, Safety 

Advisory, and Safety Bulletin. 

see also:	 Safety Advisory
 

Safety Bulletin
 

Safety Warning
 

Safety Briefing 

1	 A safety briefing emphasizes key safety concerns on the incident and is presented at each 

briefing session. The safety briefing should contain information to alert incident personnel of 

potential risk/hazard considered to be most critical. 

Safety Bulletin 

1 A safety alert containing a factual confirmation of a serious wildland fire accident, incident or 

fatality. 

see also: Safety Alert 

Safety Circle 

1	 An obstruction-free circle around the (helicopter) landing pad. 

Safety Officer 

1	 A member of the command staff responsible to the incident commander for monitoring and 

assessing hazardous and unsafe situations, and developing measures for assessing personnel 

safety. 

Safety Warning 

1 A safety alert addressing wildland fire safety hazards that pose an imminent threat, or have 

potential to pose a threat, to life or property. 

see also: Safety Alert 

Safety Zone 

1	 An area cleared of flammable materials 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 fuelbreaks; 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. 

see also:	 Deployment Zone 

Salvo 

1	 Dropping by an air tanker of its entire load of fire retardant at one time. 

Salvo Drop 

1	 Total retardant or water load dropped all at once. Usually done to knock down a hot spot. 

Sample 

1	 Part of a population; that portion of the population that is measured. 

Sample Size 

1	 The number of items or observations in a sample; usually denoted by lower case letter n. 

October 2014	 Page 153 
Glossary of Wildland Fire Terminology 

Sand Table Exercise (STEX) 

1	 A tactical decision game that employs a three-dimensional terrain model made from sand and 

various props to provide a visual representation of the situation described in the tactical decision 

game. 

Scope of Practice 

1	 The set of responsibilities and ethical considerations that define the extent or limits of the care 

provider within the current standards of practice. 

Scorch Height 

1	 Average heights of foliage browning or bole blackening caused by a fire. 

Scratch Line 

1	 An unfinished preliminary control line hastily established or constructed as an emergency 

measure to check the spread of fire. 

Scrubbing 

1	 The process of agitating foam solution and air within a confined space (usually a hose) that 

produces tiny, uniform bubbles - the length and type of hose determine the amount of scrubbing 

and, therefore, foam quality. 

Sea Breeze 

1	 A breeze (wind) blowing inland from the sea generally during daytime hours. 

Sea-level Pressure 

1	 Pressure value obtained by the theoretical reduction or increase of station pressure to sea 

level. The average atmospheric pressure at sea level is 14.7 psi. 

Season Code 

1 One of four designations of seasonal plant development used in the 1988 version of NFDRS. 

Seasonal Monthly Average 

1	 Historically, the average number of human-caused fires occurring on a protection unit per month 

during the established fire season. 

Seasonal Risk Class 

1	 Objective ranking of protection units within an administrative group based on the number of 

human-caused fires for at least the past five years. 

Second Order Fire Effects (SOFE) 

1	 The secondary effects of fire such as tree regeneration, plant succession, and changes in site 

productivity. Although second order fire effects are dependent, in part, on first order fire effects, 

they also involve interaction with many other non-fire variables. 

see also: First Order Fire Effects 

Secondary Line 

1	 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. 

Secondary Lookout 

1	 (1) A lookout point intermittently used to supplement the visible area coverage of the primary 

lookout system when required by fire danger, poor visibility, or other factors. (2) The person 

who occupies such a station. 

October 2014	 Page 154 
 

 

Glossary of Wildland Fire Terminology 

Secondary Weather Station 

1	 Station at which minimum weather measurements are taken to compute ratings of burning 

conditions; provides supplementary information on weather experience. 

Second-In-Command 

1	 Pilot who is designated to be second-in-command of an aircraft during flight time. 

Section 

1	 That organizational level with responsibility for a major functional area of the incident, such as 

operations, planning, logistics, finance/administration. The section is organizationally between 

branch and incident commander. 

Security Manager (SECM) 

1	 This ICS position is responsible for providing security safeguards to protect incident personnel 

and prevent the loss or damage of incident equipment, supplies, and property and reports to the 

Facility Unit Leader. 

see also: Facilities Unit 

Security Weather Watch 

1	 Observers are posted at one or more strategic locations in the proximity of a fire to detect and 

warn fire personnel of pending critical weather changes that might significantly affect the fire. 

Seen Area 

1 Ground, or vegetation growing thereon, that is directly visible under specified atmospheric
 

conditions from an established or proposed lookout point or aerial detection flight route. 

see also: Visible Area Map
 

Segment 

1	 A geographical area in which a task force/strike team leader or supervisor of a single resource 

is assigned authority and responsibility for the coordination of resources and implementation of 

planned tactics. A segment may be a portion of a division or an area inside or outside the 

perimeter of an incident. Segments are identified with Arabic numbers, i.e., A-1, etc. and are not 

to be used as radio designators. 

Self-Contained Breathing Apparatus (SCBA) 

1	 Portable air (not oxygen) tanks with regulators which allow firefighters to breathe while in toxic 

smoke conditions. Usually rated for 30 minutes of service. Used primarily on fires involving 

structures or hazardous materials. 

synonym: Air Pack
 

see also: Respirator
 

Separation 

1 Spacing of aircraft while landing and taking off at airports to achieve safe and orderly movement 

in flight. 

2 The horizontal and vertical spacing of aircraft working over or near a wildfire or other incident. 

3 Spacing of personnel while performing line construction activities. 

Serious Accident Investigation Team (SAIT) 

1	 A formal investigation team that is organized with the purpose of conducting an accident 

investigation for an occurred serious accident. The team is given full authorization to conduct 

the investigation from involved agencies through letter of delegation. 

Serious Aircraft Incident 

1 An incident or malfunction that could adversely affect the safety of flight. 

see also: Aircraft Incident
 

October 2014	 Page 155 
 

 

Glossary of Wildland Fire Terminology 

Service Branch 

1	 A branch within the logistics section responsible for service activities at the incident. Includes 

the communications, medical and food units. 

Service Branch Director (SVBD) 

1 The ICS position responsible for supervising the Service Branch. Reports to the Logistics
 

Section Chief. 

see also: Service Branch
 

Service Center 

1	 Point of support for items not ordered through dispatch. 

Set 

1 An individual incendiary fire.
 

2 The point or points of origin of an incendiary fire. 

3 Material left to ignite an incendiary fire at a later time. 

4 Individual lightning or railroad fires, especially when several are started within a short time. 

5 Burning material at the points deliberately ignited for backfiring, slash burning, prescribed
 

burning, and other purposes. 

Severity 

see:	 Fire Severity 

Severity Funding 

1	 Suppression funds used to increase the level of presuppression capability and fire 

preparedness when predicted or actual burning conditions exceed those normally expected, due 

to severe weather conditions. 

Severity Index 

1	 A number that indicates the relative net effects of daily fire danger on the fire load for an area 

during a specified period, such as a fire season. 

Shaded Fuelbreak 

1	 Fuelbreaks built in timbered areas where the trees on the break are thinned and pruned to 

reduce the fire potential yet retain enough crown canopy to make a less favorable microclimate 

for surface fires. 

Shareable Content Object (SCO) 

1 Self-contained units of learning. They can be used as building blocks (or legos) to create 

packages (lessons) of SCOs, but they cannot be broken down into smaller units. 

see also: Learning Content Management System
 

Learning Objects
 

Shareable Content Object Re-usable Model (SCORM) 

1	 A specification for standardizing the reusability and interoperability of learning content. SCORM 

has been developed by the Advanced Distributed Learning initiative (ADL). 

SCORM focuses on two critical pieces of learning content interoperability: 

1.) It defines an aggregation model for packaging learning content. 

2.) It defines an API for enabling communications between learning content and the system that 

launches it. 

see also: Learning Content Management System 

Shock Wave 

1	 The leading edge of an expanding air mass. 

October 2014	 Page 156 
 

 

 

 

Glossary of Wildland Fire Terminology 

Short Takeoff or Landing (STOL) Aircraft 

1	 An aircraft which has the capability of operating from a STOL runway in accordance with 

applicable airworthiness and operating regulations.
 

Short Takeoff or Landing (STOL) Airstrip 

1 Developed or undeveloped area that has been tested and will accommodate STOL aircraft. 

Short-Range Spotting 

1	 Firebrands, flaming sparks, or embers are carried by surface winds, starting new fires beyond 

the zone of direct ignition by the main fire. The range of such spotting is usually less than 1/4 

mile. 

Short-Term 

1	 Persons or work for which employment is less than 12 months (excluding firefighters hired for a 

particular fire). 

Short-Term Fire Retardant 

1	 Fire retardant that inhibits combustion primarily by the cooling and smothering action of water. 

Chemicals may be added to the water to alter its viscosity or retard its evaporation, thereby 

increasing its effectiveness. 

Shoulder Carry 

1	 Method of carrying hose on the shoulders. 

Shrub 

1	 A woody perennial plant differing from a perennial herb by its persistent and woody stem; and 

from a tree by its low stature and habit of branching from the base. 

Shrub Type 

1	 The two-category (evergreen, deciduous) classification of shrubs vegetation in the 1988 version 

of NFDRS. 

Shutoff Nozzle 

1	 Common type of fire hose nozzle permitting stream flow to be controlled by the firefighter at the 

nozzle rather than only at the source of supply. 

Shutoff Pressure 

1	 Maximum pressure a centrifugal pump will attain when water flow is clamped or shut off. 

Siamese 

1 Hose fitting (preferably gated) for combining flow from two or more lines of hose into a single 

stream; one male coupling to two female couplings. 

see also: Reversible Siamese 

Wye 

Significant Fire Event 

1	 An event measured by the occurrence of fire(s) that requires mobilization of additional 

resources from outside the fire event area.
 

Significant Fire Potential 

1	 The likelihood a wildland fire event will require mobilization of additional resources from outside 

the area in which the fire situation originates. 

Significant Weather Trigger 

1	 A weather phenomenon resulting in an environment that has a significant impact on fire spread, 

intensity, or occurrence. Example: strong wind, unstable air mass, etc. 

October 2014	 Page 157 
 

 

Glossary of Wildland Fire Terminology 

Simms Bucket 

1	 Self-leveling helibucket slung under a helicopter which can be filled by hovering over a water 

source. 

Simple Hose Lay 

1	 A hoselay consisting of consecutively coupled lengths of hose without laterals. The lay is 

extended by inserting additional lengths of hose in the line between pumps and nozzle. Also 

called single hose lay. 

Simulation 

1	 A realistic portrayal of a task or operation that enables the operator/trainee to experience, under 

artificial conditions, situations likely to occur in actual performance of duty. Simulations are 

highly effective when dealing with hazardous or extremely expensive conditions. 

2	 An activity that imitates something real, but it's not real itself and it can be altered by users for 

the specific purpose of providing an experiential learning environment. (Examples: Sand Table 

Exercise or CBT/WBT Forest Service Wildland Fire Simulation Scenario Editor) 

Single Arsonist 

1	 An offender who intentionally sets one fire. 

Single Door Drop 

1	 Technique whereby fire retardant is released from only one compartment of an air tanker. 

Single Resource 

1	 An individual, a piece of equipment and its personnel complement, or a crew or team of 

individuals with an identified work supervisor that can be used on an incident.
 

Single Stage Pump 

1	 Centrifugal pump with a single impeller. 

Site Preparation 

1	 Removal or killing of unwanted vegetation, residue, etc. by use of fire, herbicides, or mechanical 

treatment in preparation for reforestation and future management. 

Site Preparation Burning 

1	 Fire ignited to expose adequate mineral soil and control competing vegetation until seedlings of 

the desired species become established. 

Situation Analysis 

1	 Analysis of factors which influence suppression of an escaped fire from which a plan of attack 

will be developed; includes development of alternative strategies of fire suppression and net 

effect of each. 

Situation Awareness (SA) 

1 An on-going process of gathering information by observation and by communication with others. 

This information is integrated to create an individual's perception of a given situation. 

synonym: Situational Awareness 

Situation Unit 

1 Functional unit within the planning section responsible for the collection, organization and
 

analysis of incident status information, and for analysis of the situation as it progresses. 

Reports to the planning section chief. 

Situation Unit Leader (SITL) 

1 The ICS position responsible for supervising the Situation Unit. Reports to the Planning Section 

Chief. 

see also: Situation Unit 

October 2014	 Page 158 
 

Glossary of Wildland Fire Terminology 

Situational Awareness (SA) 

1 An on-going process of gathering information by observation and by communication with others. 

This information is integrated to create an individual's perception of a given situation. 

synonym: Situation Awareness 

Six Minutes for Safety 

see:	 6 Minutes for Safety 

Size Class of Fire 

1	 As to size of wildfire: 

Class A - one-fourth acre or less;
 

Class B - more than one-fourth acre, but less than 10 acres; 

Class C - 10 acres or more, but less than 100 acres;
 

Class D - 100 acres or more, but less than 300 acres; 

Class E - 300 acres or more, but less than 1,000 acres; 

Class F - 1,000 acres or more, but less than 5,000 acres; 

Class G - 5,000 acres or more. 

see also: Class of Fire 

Sizeup 

1	 The evaluation of the fire to determine a course of action for suppression. 

Skid Hose Load 

1	 Load of hose specially arranged on top of a standard hose load to permit dropping the working 

line at the fire. 

Skid Trail 

1	 Any road or trail formed by the process of skidding logs from stump to landing. 

Skidder Unit 

1	 A self-contained unit consisting of a water tank, fire pump, and hose specially designed to be 

carried on a logging skidder for use in forest fire suppression. 

Skimmer 

1	 Any aircraft equipped to pick up water while moving on or over water. 

Sky Cover 

1	 Amount of clouds and/or other obscuring phenomena that are detectable from the point of 

observation. 

Slash 

1	 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 understory trees or brush. 

Slash Disposal 

1 Treatment of slash to reduce fire hazard or for other purposes. (Preferred to Brush Disposal). 

Sling 

1	 A net attached by a lanyard to a helicopter cargo hook and used to haul supplies. 

Sling Load 

1	 Any cargo carried beneath a helicopter and attached by a lead line and swivel. 

Sling Psychrometer 

1	 A hand operated instrument for obtaining wet and dry bulb temperature readings and, 

subsequently, relative humidity. 

October 2014	 Page 159 
 

Glossary of Wildland Fire Terminology 

Slip-on Tanker 

1	 A tank, a live hose reel or tray, an auxiliary pump, and an engine combined into a single onepiece assembly which can be slipped onto a truck bed or trailer. 

Slope Class 

1	 One of five categories used to describe the topography of a fire danger rating area. 

Slope Percent 

1	 The ratio between the amount of vertical rise of a slope and horizontal distance as expressed in 

a percent. One hundred feet of rise to 100 feet of horizontal distance equals 100 percent. 

Slope Winds 

1 Small scale convective winds that occur due to local heating and cooling of a natural incline of 

the ground. 

see also: General Winds 

Local Winds 

Slopover 

1 A fire edge that crosses a control line or natural barrier intended to confine the fire. 

synonym: Breakover
 

Slug Flow 

1	 The discharge of distinct pockets of water and air due to the insufficient mixing of foam
 

concentrate, water, and air in a compressed air foam system. 

Small Aircraft 

1	 An aircraft of 12,500 pounds (5,669 kg) or less, maximum certificated takeoff weight. 

Smog 

1	 Generally considered only photochemical air pollution. Originally meant a combination of smoke 

and fog. 

Smoke 

1	 Small particles of carbon, tarry and water vapor resulting from the incomplete combustion of 

carbonaceous materials such as wood, coal or oil. 

Smoke Concentration 

1	 The amount of combustion products found in a specified volume of air, commonly expressed as 

micrograms of emission per cubic meter of air. 

Smoke Intrusion 

1	 Smoke from prescribed fire entering a designated area at unacceptable levels. 

Smoke Management 

1	 The policies and practices implemented by air and natural resource managers directed at 

minimizing the amount of smoke entering populated areas or impacting sensitive sites, avoiding 

significant deterioration of air quality and violations of National Ambient Air Quality Standards, 

and mitigating human-caused visibility impacts in Class I areas. 

Smoke Pall 

1	 Extensive, thick blanket of smoke spreading more or less horizontally from a fire. 

Smoke Plume 

1 The gases, smoke, and debris that rise slowly from a fire while being carried along the ground 

because the buoyant forces are exceeded by those of the ambient surface wind. 

see also: Convection Column 

October 2014	 Page 160 
 

 

Glossary of Wildland Fire Terminology 

Smoke Target 

1	 An area that may be adversely affected by smoke from a prescribed burn. Also called smoke 

sensitive area. 

Smoke Vent Height 

1	 Level, in the vicinity of the fire, at which the smoke ceases to rise and moves horizontally with 

the wind at that level. 

Smokejumper 

1	 A specifically trained and certified firefighter who travels to wildland fires by aircraft and 

parachutes to the fire. 

Smoke-Sensitive Area (SSA) 

1	 Area in which smoke from outside sources is intolerable, for reasons such as heavy population, 

existing air pollution, or intensive recreation or tourist use. 

Smokey Bear 

1	 The symbol of the Cooperative Forest Fire Prevention Program since 1945. Smokey's image is 

protected by US Federal Law and is administered by the USDA Forest Service, the National 

Association of State Foresters and the Ad Council. 

Smoking (As a Fire Cause) 

1	 Wildfires caused by smokers from matches, lighters, tobacco, or other smoking material. 

Smoldering Combustion 

1	 Combined processes of dehydration, pyrolysis, solid oxidation, and scattered flaming 

combustion and glowing combustion, which occur after the flaming combustion phase of a fire; 

often characterized by large amounts of smoke consisting mainly of tars. 

Smoldering Combustion Phase 

1 Phase of combustion immediately following flaming combustion. Emissions are at twice that of 

the flaming combustion phase. 

see also: Smoldering Combustion 

Snag 

1	 A standing dead tree or part of a dead tree from which at least the leaves and smaller branches 

have fallen. Often called a stub, if less than 20 feet tall. 

Snorkel Tank 

1	 A fixed tank attached to the belly of the helicopter that has a pump-driven snorkel attached. The 

helicopter hovers over the water source with the end of the snorkel immersed, the pump then 

fills the tank. 

Soft Suction 

1	 Commonly accepted term for short length of large diameter soft hose used to connect a 

structural or wildland engine with a hydrant. No vacuum is involved because the hose is useful 

only when the engine receives water at a rate of flow in excess of the demand of the pump. 

Solar Radiation 

1	 The amount of sunlight exposed to the fuels. 

Soot 

1	 Carbon dust formed by incomplete combustion. 

Sooting Indicators 

1	 The black, carbon based soot deposited on objects in the fire's path. Found on the side of 

objects towards the origin. 

October 2014	 Page 161 
 

 

Glossary of Wildland Fire Terminology 

Sortie 

1	 Single round trip made by an air tanker from a tanker base to a fire and return. 

Sound Warbler 

1	 A signaling device mounted on retardant aircraft which generates a tremulous siren sound to 

warn firefighters on the ground that a plane is approaching to drop retardant. 

Sounding (Upper Air Sounding) 

1	 A sampling of upper air conditions made by means of instruments and a small radio transmitter 

on a free balloon. Automatic radio signals originated by action of weather instruments are sent 

to a ground receiver. These signals are interpreted for use in analyzing and predicting upper air 

conditions over a wide area of the earth. Weather elements determined at a number of altitude 

points as the balloon rises are temperature, atmospheric moisture, pressure, wind direction and 

speed. Similar soundings may be made using fixed balloons or tethersondes. 

see also: Radiosonde 

Source 

1	 A point, line, or area, at which mass or energy is added to a system, either instantaneously or 

continuously. Examples of sources in the context of air pollution are as follows: a smoke stack is 

a point source; a freeway is a line source; field or slash burning are area sources. 

Spalling 

1	 Chipping or pitting of concrete, masonry, or stone surfaces. 

Spalling Indicators 

1	 Craters or chips in the surface of rocks which indicate direction of fire spread. 

Span 

1	 Distance equal to the wingspread of the air tanker being used; used for corrections right or left 

of the flight path. 

Span of Control 

1	 The supervisory ratio of from three-to-seven individuals, with five-to-one being established as 

optimum. 

Spanner 

1	 Metal wrench used to tighten and free hose connections. 

Spark Arrester 

1	 A device installed in a chimney, flue, or exhaust pipe to stop the emission of sparks and burning 

fragments. 

Special Interest Group (SIG) 

1	 In WIMS, a group of weather stations. 

Special Visual Flight Rules (VFR) 

1	 Aircraft operating in accordance with clearances within control zones in weather conditions less 

than the basic Visual Flight Rules weather minima. 

Specific Heat 

1	 The heat required to raise a unit mass of a substance one degree kelvin. It is the heat capacity 

of a system per unit mass; i.e., the ratio of the heat absorbed (or released) to the corresponding 

temperature rise (or fall). 

Specific Origin Area 

1	 The smaller area, within the general origin, that first shows the influence of wind, fuel and/or 

slope. 

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Glossary of Wildland Fire Terminology 

Speed of Attack 

1	 Elapsed time from origin of fire to arrival of the first suppression force. 

Spike-Out 

1	 Standby crew in an area of expected high fire occurrence, generally on a day of critical fire 

weather. 

Split Drop 

1	 Retardant drop made from one compartment at a time from an air tanker with a multicompartment tank.
 

Split Flow 

1	 A divergent wind field. Storms moving into a split field tend to lose strength. Winds are 

generally light in such a flow field. 

Spontaneous Combustion 

1	 Combustion of a thermally isolated material initiated by an internal chemical or biological
 

reaction producing enough heat to cause ignition. 

Spot Burning 

1	 A modified form of broadcast slash burning in which the greater accumulations of slash are fired 

and the fire is confined to these spots. Sometimes called "Jackpot Burning" or "Jackpotting." 

Spot Fire 

1	 Fire ignited outside the perimeter of the main fire by a firebrand. 

Spot Fire Technique 

1	 A method of lighting prescribed fires where ignition points are set individually at a predetermined 

spacing and with predetermined timing throughout the area to be burned. 

Spot Weather Forecast 

1	 A special forecast issued to fit the time, topography, and weather of a specific incident. These 

forecasts are issued upon request of the user agency and are more detailed, timely, and 

specific than zone forecasts. Usually, on-site weather observations or a close, representative 

observation is required for a forecast to be issued. 

see also:	 General Fire Weather Forecast
 

Incident Weather Forecast
 

Spot Forecast
 

Spotter 

1	 In smokejumping, rappelling, and paracargo operations, the individual responsible for selecting 

drop target and supervising all aspects of dropping smokejumpers, rappellers, or cargo. 

Spotting 

1	 Behavior of a fire producing sparks or embers that are carried by the wind and which start new 

fires beyond the zone of direct ignition by the main fire. 

Spray 

1	 Water applied through an orifice in finely divided particles to absorb heat and smother fire, to 

protect exposures from radiated heat, and to carry water toward otherwise inaccessible fire. 

Spread Component 

1	 Part of the National Fire Danger Rating System (NFDRS). A rating of the forward rate of spread 

of the head of a fire. 

Spread Index 

1	 A number used to indicate relative (not actual) rate of spread. 

October 2014	 Page 163 
Glossary of Wildland Fire Terminology 

Spread Index Meter 

1	 Device for combining measured ratings of various fire danger factors into numerical classes or 

rates of spread. 

Spur Ridge 

1	 A small ridge which extends finger-like from a main ridge. 

Squall 

1	 Sudden increase in wind speed to at least 17 mph (15 knots) that is sustained for at least 1 

minute but not more than 5 minutes. 

Squall Line 

1	 Any nonfrontal line or narrow band of active thunderstorms extending across the horizon. It is of 

importance to fire behavior due to accompanying strong gusty winds and the possibility of such 

a line passing between regular weather observation stations without being reported. Also called 

line squall. 

Stable Atmosphere 

1	 Condition of the atmosphere in which the temperature decrease with increasing altitude is less 

than the dry adiabatic lapse rate. In this condition, the atmosphere tends to suppress largescale vertical motion. Also called stable air. 

Stable Layer of Air 

1	 A layer of air having a temperature change (lapse rate) of less than dry adiabatic 

(approximately -5.4 degrees F per 1,000 feet) thereby retarding either upward or downward 

mixing of smoke. 

see also:	 Atmospheric Inversion
 

Atmospheric Stability
 

Inversion
 

Stack 

1	 Aircraft orbiting the rendezvous area; usually refers to vertical deployment at 500-foot (150 m) 

altitudinal separation between aircraft. 

Staff Ride 

1	 A case study of a previous incident that is conducted on the actual physical site where the 

incident occurred. A staff ride is an experiential learning method that involves three distinct 

parts: a preliminary study, a site visit, and a post-visit integration session. 

Staffing Index 

1	 A NFDRS component, index or related indicator (ignition component, spread component, energy 

release component, burning index, Keetch-Byram drought index) whose outputs are correlated 

to the local fire problem, used to determine staffing levels. 

Staffing Level 

1	 The basis for decision support for daily staffing of initial attack resources and other activities. A 

level of readiness and an indicator or daily preparedness. 

Staging Area 

1	 Locations set up at an incident where resources can be placed while awaiting a tactical
 

assignment on a three (3) minute available basis. Staging Areas are managed by the 

Operations Section. 

Staging Area Manager (STAM) 

1 The ICS position responsible for supervising a staging area. Reports to a Branch Director or 

Operations Section Chief. 

see also: Staging Area 

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Glossary of Wildland Fire Terminology 

Stagnant Conditions 

1	 Atmospheric conditions under which pollutants build up faster than the atmosphere can disperse 

them. 

Staining Indicators 

1	 Glossy, varnish-like stain, usually light yellow to orange to dark brown in color, which is
 

deposited on the origin side of objects. 

Stand Replacing Fire 

1 Fire which kills all or most of the living overstory trees in a forest and initiates forest succession 

or regrowth. Also explicitly describes the nature of fire in grasslands and some shrublands. 

Standard Coupling 

1	 Fire hose coupling with American National Standard (NH) threads. 

Standard Drying Day 

1	 Part of the National Fire Danger Rating System (NFDRS). Day which produces the same net 

drying as experienced during a 24-hour period under laboratory conditions in which dry-bulb 

temperature is maintained at 80° F and relative humidity is maintained at and relative humidity is 

maintained at 20%. 

Standard Hydrologic Exchange Format code (SHEF) 

1	 A two-character code to describe each measurement taken at a weather station. 

Standard Operating Procedure (SOP) 

1	 Specific instructions clearly spelling out what is expected of an individual every time they 

perform a given task. A standard operating procedure can be used as a performance standard 

for tasks that are routinely done in the operational environment. 

synonym: Standard Operational Procedure 

Standard Operational Procedure (SOP) 

1	 Specific instructions clearly spelling out what is expected of an individual every time they 

perform a given task. A standard operational procedure can be used as a performance standard 

for tasks that are routinely done in the operational environment. 

synonym: Standard Operating Procedure 

Stand-By Crew 

1	 A group of trained firefighters stationed at a dispatch point for quick, rapid deployment. 

State Forest 

1	 Forests owned and administered by a state, and not by a federal government. 

State Implementation Plan (SIP) 

1	 A plan required by the Clean Air Act and prepared by an Air Quality Regulatory Agency, which 

describes how the state will attain and maintain air quality so as to not violate National Ambient 

Air Quality Standards. 

State of Weather 

1	 A code which expresses the amount of cloud cover, kind of precipitation, and/or restrictions to 

visibility being observed at the fire danger station at basic observation time. 

State Park 

1	 An area established by the government of a state primarily for public recreation or for the 

preservation of unique natural or historic resources, administrative details varying widely. NOTE: 

Such parks may also be established by lesser administrative units, e.g. counties, municipalities, 

and also by large private owners. 

October 2014	 Page 165 
 

Glossary of Wildland Fire Terminology 

Static Pressure 

1	 Water pressure head available at a specific location when no water is being used so that no 

friction loss is being encountered. Static pressure is that pressure observed on the engine inlet 

gauge before any water is taken from the hydrant. 

Static Water Supply 

1	 Supply of water at rest which does not provide a pressure head for fire suppression but which 

may be employed as a suction source for fire pumps (e.g., water in a reservoir, pond, or 

cistern). 

Station Catalog 

1	 A WIMS file that contains all the information defined for a weather station. 

Station ID 

1	 A six-digit number assigned to a specific weather station by the servicing National Weather 

Service Fire Weather Office. 

Station Pressure 

1	 Pressure of the atmosphere at an assigned station location and elevation. 

Statistic 

1 The number that results from manipulating raw data according to a specified procedure; 

associated with samples.
 

see also: Parameter
 

Statistical Fire 

1	 In general, an actionable fire, on which any fire agency reports and maintains specified 

information (e.g., cause, date and point of origin, size, fire damage). 

Statistics 

1	 A branch of mathematics dealing with the collection, analysis, and interpretation of numerical 

data. 

Status/Check-In Recorder (SCKN) 

1	 This ICS position is responsible for checking in and maintaining current status for incident 

assigned resources and reports to the Resources Unit Leader. Each incident check-in location 

will have at least one Check-In Recorder assigned. 

see also: Resources Unit 

Step Test 

1	 Five-minute test used to predict a person's ability to take in, transport, and use oxygen (aerobic 

capacity), the most important factor limiting the ability to perform arduous work. 

Storm Center 

1	 The central point or area of a weather system associated with increased winds, clouds or
 

precipitation (or any combination thereof). 

Straight Stream 

1	 Water or fire retardant projected directly from the nozzle (as contrasted with a fog or spray 

cone), provided by a solid stream orifice or by adjusting a fog jet into a straight stream pattern. 

Straight Stream Nozzle 

1	 A hose tip spout designed to provide the maximum reach of water without feathering. 

October 2014	 Page 166 
 

 

Glossary of Wildland Fire Terminology 

Strainer 

1	 A wire or metal guard used to keep debris from clogging pipe or other openings made for 

removing water; used in pumps and on suction hose to keep foreign material from clogging or 

damaging pumps. 

Strategic Objective 

1	 A broad statement, specified in a land/resource management or fire management plan that 

identifies change in water, soil, air, or vegetation from the present to proposed conditions, or 

describes an existing resource condition that should be maintained. Strategic objectives deal 

with large areas over long time periods and project intended outcomes of management activities 

that contribute to the maintenance or achievement of desired conditions. 

Strategy 

1	 The general plan or direction selected to accomplish incident objectives. 

Strength of Attack 

1	 Number of resources used to attack a fire. 

Strength of Force 

1	 Total firefighting resources available, during a specified period, to conduct and support 

firefighting operations. 

Strike Team 

1	 Specified combinations of the same kind and type of resources, with common communications, 

and a leader. 

Strike Team Leader (STCR, STDZ, STEN or STPL) 

1	 The ICS position responsible for supervising a strike team. Reports to a Division/Group 

Supervisor or Operations Section Chief. This position may supervise a strike team of engines 

(STEN), crews (STCR), dozers (STDZ),or tractor/plows (STPL). 

see also: Strike Team 

Strike Team leader Crew (STCR) 

1 This ICS position is responsible for the direct supervision of a crew strike team. 

see also: Strike Team
 

Strike Team Leader Dozer (STDZ) 

1 This ICS position is responsible for the direct supervision of a dozer strike team. 

see also: Strike Team
 

Strike Team Leader Engine (STEN) 

1 This ICS position is responsible for the direct supervision of an engine strike team. 

see also: Strike Team
 

Strike Team Leader Tractor/Plow (STPL) 

1 This ICS position is responsible for the direct supervision of a tractor/plow strike team. 

see also: Strike Team
 

Stringer 

1 A narrow finger or band of fuel that connects two or more patches or areas of wildland fuel. 

Strip Burning 

1 Burning by means of strip firing. 

2 In hazard reduction, burning narrow strips of fuel and leaving the rest of the area untreated by 

fire. 

October 2014	 Page 167 
 

 

 

 

Glossary of Wildland Fire Terminology 

Strip Firing 

1	 Setting fire to more than one strip of fuel and providing for the strips to burn together. 

Frequently done in burning out against a wind where inner strips are fired first to create drafts 

which pull flames and sparks away from the control line. 

Strip-Head Fire 

1	 A series of lines of fire ignited near and up wind (or downslope) of a firebreak or backing fire so 

they burn with the wind (or upslope) toward the firebreak or backing fire. 

Structural Fire Protection 

1	 The protection of homes or other structures from wildland fire. 

Structure 

1	 A constructed object, usually a free-standing building above ground. 

Structure (Vegetative) 

1	 The arrangement of vegetation in terms of density, basal area, cover, and vertical arrangement. 

Structure Fire 

1	 Fire originating in and burning any part or all of any building, shelter, or other structure. 

Structure Protection Plan 

1 A plan developed by the Structure Protection Specialist that provides operational guidelines to 

suppression resources responsible for providing wildland fire structure protection. 

see also: Structure Protection Specialist 

Structure Protection Specialist (STPS) 

1	 An individual responsible for developing an incident's structure protection plan, providing tactical 

direction and recommendations to incident planning and operations on efficient and safe 

utilization of resources assigned to provide wildland fire structure protection. 

see also: Structure Protection Plan 

Subsidence 

1	 Downward or sinking motion of air in the atmosphere. Subsiding air warms due to compression. 

Increasing temperature and decreasing humidities are present in subsiding air. Subsidence 

results in a stable atmosphere inhibiting dispersion. Subsidence is generally associated with 

high atmospheric pressure. 

Subsidence Inversion 

1	 An inversion caused by subsiding air, often resulting in decreased atmospheric mixing 

conditions. 

Succession 

1	 The process of vegetational development whereby an area becomes successively occupied by 

different plant communities of higher ecological order. 

Suction Lift 

1	 In fire service, the number of feet (meters) of vertical lift from the surface of the water to the 

center of the pump impeller. In testing, e.g., fire department pumpers are required to discharge 

their rated capacity at 150 pounds (1034 kPa) net pump pressure at a 10-foot (3 meter) lift. The 

suction gauge would indicate the vertical suction lift in inches of mercury when the pump was 

primed with no appreciable water flowing. 

Sunny 

1	 The adjective classification of the sky when 5/10 or less of the sky is obscured by clouds. Part of 

the National Fire Danger Rating System (NFDRS). 

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Glossary of Wildland Fire Terminology 

Sunset and Sunrise 

1	 The mean solar times of sunset and sunrise as published in the Nautical Almanac, converted to 

local standard time for the locality concerned. 

Superficial Burn 

1	 A minor thermal burn involving the outer layer of skin, i.e. "a sunburn". It is characterized by 

reddening of the skin and perhaps some swelling without blisters. (also called First Degree 

Burn) 

see also:	 Full-thickness Burn
 

Partial-thickness Burn
 

Supervisor 

1	 The ICS title for individuals responsible for command of a division or group. 

Supplemental Fire Department Resources 

1	 Overhead tied to a local fire department, generally by agreement, who are mobilized primarily 

for response to incidents or wildland fires outside their district or mutual aid zone. Supplemental 

fire department resources are not a permanent part of the local fire organization and are not 

required to attend scheduled training, meetings, etc. of the department staff. 

Supplies 

1	 Minor items of equipment and all expendable items assigned to an incident. 

Supply Unit 

1	 Functional unit within the support branch of the logistics section responsible for ordering 

equipment and supplies required for incident operations. 

Supply Unit Leader (SPUL) 

1 The ICS position responsible for supervising the Supply Unit. Reports to the Support Branch 

Director or Logistics Section Chief. 

see also: Supply Unit 

Support Branch 

1	 A branch within the logistics section responsible for providing personnel, equipment and 

supplies to support incident operations. Includes the supply, facilities and ground support units. 

Support Branch Director (SUBD) 

1 The ICS position responsible for supervising the Support Branch. Reports to the Logistics 

Section Chief. 

see also: Support Branch
 

Support Costs 

1	 On-incident costs and off-incident costs. On-incident costs include caterer, shower units, mobile 

commissary, cache supplies, and materials, etc. Off-incident costs include expanded dispatch, 

buying teams, administrative payment teams, cache personnel, area command, transportation 

to/from incident, etc. 

Support Resources 

1	 Non-tactical resources under the supervision of the logistics, planning, finance/administration 

sections or the command staff. 

Supporting Agency 

1 An agency providing suppression or other support and resource assistance to a protecting 

agency. 

see also:	 Agency
 

Assisting Agency
 

Cooperating Agency
 

October 2014	 Page 169 
 

Glossary of Wildland Fire Terminology 

Supporting Technologies 

1	 Any technology which may be used to support NIIMS. Examples of these technologies include 

GIS mapping, infrared technology, NFDRS, communications, dispatch coordination, and 

national cache system. 

see also: National Interagency Incident Management System 

Suppress a Fire 

see:	 Suppression 

Suppressant 

1	 An agent that extinguishes the flaming and glowing phases of combustion by direct application 

to the burning fuel. 

Suppression 

1	 Management action to extinguish a fire or confine fire spread beginning with its discovery. 

Suppression Crew 

1	 Two or more firefighters stationed at a strategic location for initial action on fires. Duties are 

essentially the same as those of individual firefighters. 

Suppression Firing 

1	 Intentional application of fire to speed up or strengthen fire suppression action on wildfires. 

Types of suppression firing include burning out, counter firing, and strip burning. 

Surface Area-to-Volume Ratio 

1	 The ratio between the surface area of an object, such as a fuel particle, to its volume. The 

smaller the particle, the more quickly it can become wet, dry out, or become heated to 

combustion temperature during a fire. 

Surface Fire 

1	 Fire that burns loose debris on the surface, which includes dead branches, leaves, and low 

vegetation. 

Surface Fuel 

1	 Fuels lying on or near the surface of the ground, consisting of leaf and needle litter, dead branch 

material, downed logs, bark, tree cones, and low stature living plants. 

Surface High 

1	 An area on the earth's surface where atmospheric pressure is at a relative maximum. Winds 

blow clockwise around highs in the Northern Hemisphere but, due to friction with the earth's 

face, tend to cross constant pressure lines away from the high center. Air is usually subsiding 

above a surface high. This causes warming due to air compression. This results in stable 

atmospheric conditions and light surface winds. 

see also: Ridge 

Surface Low 

1	 An area on the earth's surface where atmospheric pressure is at a relative minimum. Winds 

blow counter-clockwise around lows in the Northern Hemisphere but, due to friction with the 

earth's surface, tend to cross constant pressure lines toward the low center. Upon converging 

into the low's center, air currents are forced to rise. As air rises it cools due to expansion. 

Cooling reduces its capacity to hold moisture; so cloudiness and precipitation are common in 

lows. If a low center intensifies sufficiently it will take on the characteristics of a storm center with 

precipitation and strong winds. 

October 2014	 Page 170 
 

 

Glossary of Wildland Fire Terminology 

Surface Tension 

1	 The elastic-like force at the surface of a liquid, tending to minimize the surface area and causing 

drops to form. Expressed as Newtons per meter or dynes per centimeter (1 Newton/m=1,000 

dynes/cm). 

Surface Wind 

1	 Wind measured at a surface observing station, customarily at some distance (usually 20 feet) 

above the average vegetative surface to minimize the distorting effects of local obstacles and 

terrain. 

Surfactant 

1	 A surface active agent; any wetting agent. A formulation which, when added to water in proper 

amounts, will materially reduce the surface tension of the water and increase penetration and 

spreading abilities of the water. 

Surge 

1	 Rapid increase in water flow which may result in a corresponding pressure rise. 

Surplus Property 

1	 Any excess personal property not required for the needs and the discharge of the 

responsibilities of all federal agencies as determined by the General Services Administration 

(GSA). 

Survival Zone 

1	 A natural or cleared area of sufficient size and location to protect fire personnel from known 

hazards while inside a fire shelter. Examples include rock slides, road beds, clearings, knobs, 

wide ridges, benches, dozer lines, wet areas, cleared areas in light fuels, and previously burned 

areas. These are all areas where you expect no flame contact or prolonged heat and smoke. 

see also:	 Deployment Zone
 

Safety Zone
 

Sustained Attack 

1	 Continuing fire suppression action until fire is under control. 

Swamper 

1 A worker who assists fallers and/or sawyers by clearing away brush, limbs and small trees. 

Carries fuel, oil and tools and watches for dangerous situations. 

3 A worker on a dozer crew who pulls winch line, helps maintain equipment, etc., to speed 

suppression work on a fire. 

Swampout 

1	 Act of clearing brush and other material from around the base of trees and where trees are to be 

bucked, prior to falling or bucking, as protection against saw kickback and to provide safe 

footing. 

Swivel 

1	 An accessory used between the helicopter cargo hook and sling load to allow free turning of the 

load. 

Synoptic 

1	 Literally, at one time. Thus, in meteorological usage, the weather conditions over a large area at 

a given point in time. 

Synoptic Chart 

1	 In meteorology, any chart or map on which data and analyses are presented that describe the 

state of the atmosphere over a large area at a given moment in time. 

October 2014	 Page 171 
Glossary of Wildland Fire Terminology 

- T -

Tactical Decision Game (TDGS) 

1	 A simple role-play simulation technique that challenges participants to make decisions and 

communicate those decisions to others. A tactical decision game is an experiential learning 

method that is tactical in nature and has time and information constraints to put participants 

under some level of stress. http://www.fireleadership.gov 

Tactical Direction 

1	 Direction given by the operations section chief which includes the tactics appropriate for the 

selected strategy, the selection and assignment of resources, tactics implementation, and 

performance monitoring for each operational period. 

Tactics 

1	 Deploying and directing resources on an incident to accomplish the objectives designated by 

strategy. 

Tag-on 

1	 Connecting a (airtanker) drop to the forward part of a previous drop. 

Tail Rotor 

1	 A small rotor, mounted on the tail of a conventional helicopter, which counteracts torque of the 

main rotor and provides a measure of directional control. 

Tailboard 

1	 Back step of a wildland or structural fire engine. 

Tailgate Safety Session 

1	 Brief meetings held at the beginning, during, or end of an operational period to discuss new 

work assignments, new work methods, changes in plans, use of tools and equipment, and 

recognition and protection against work hazards that may be encountered. 

Take-off and Landing Coordinator (TOLC) 

1	 This ICS position is responsible for coordinating take-offs and landings of helicopters at a 

helibase and any helicopter movement around the helibase and reports to the Helibase 

Manager. 

see also: Helibase 

Tandem 

1	 Two or more units of any one type working one in front of the other to accomplish a specific fire 

suppression job; the term can be used in connection with crews of firefighters, power pumps, 

bulldozers, etc. 

Tank and Gating System 

1	 Tanks, doors, and release mechanism installed in aircraft for cascading fire retardants. 

Tank Trailer 

1	 Specialized trailer on which is mounted a tank, fire pump, hose, and ancillary equipment. 

Target 

1 Specific portion of the fire on which fire retardant or water is to be dropped by air tankers or 

helitankers. 

see also: Drop Zone 

October 2014	 Page 172 
Glossary of Wildland Fire Terminology 

Target Hazard 

1 Facilities in which there is great likelihood of loss of life or property. 

Task 

1 A unit of work activity that is a logical and necessary action in the performance of a behavior; 

how the behavior is demonstrated or performed in a particular context. 

see also: Behavior 

Task Force 

1	 Any combination of single resources assembled for a particular tactical need, with common 

communications and a leader. A task force may be pre-established and sent to an incident, or 

formed at an incident. 

Task Force Leader (TFLD) 

1 The ICS position responsible for supervising a task force. Reports to a Division/Group 

Supervisor or Operations Section Chief. 

see also: Task Force 

T-Card 

1	 Cards filled out with essential information for each resource they represent. The cards are colorcoded to represent different types of resources. 

Technical Advisory Unit 

1	 This unit consists of advisors with special skills who are activated only when needed. Advisors 

may be needed in the areas of water resources, environmental concerns, resource use, and 

training. 

Technical Specialist (THSP) 

1	 An individual with specialized job skills requiring no established minimum qualifications 

standards by the wildland fire community. THSP may perform the same duties during an 

incident that are performed in their regular job assignment with supplemental training in the 

Incident Command System and/or adaptations of their specialized skills for the incident 

environment that they are assigned. These specialized individuals whose skills may be gained 

through educational degree programs or industrial training required by established standards 

may be utilized anywhere within an incident organization. 

Temperature Coefficient 

1	 The relative change of some measurable quantity with change of temperature, like burning time 

per unit length, mostly expressed as mean change per degree in percentage of mean 

temperature within a certain range. 

Temporary Flight Restriction (TFR) 

1	 A restriction requested by an agency and put into effect by the Federal Aviation Administration 

in the vicinity of an incident which restricts the operation of nonessential aircraft in the airspace 

around that incident. 

Ten-hour Timelag Fuel Moisture (10-h TL FM) 

1	 The moisture content of the l0-hour timelag roundwood fuels. 

Ten-hour Timelag Fuels 

1	 Dead fuels consisting of roundwood 1/4 to l-inch (0.6 to 2.5 cm) in diameter and, very roughly, 

the layer of litter extending from immediately below the surface to 3/4 inch (1.9 cm) below the 

surface. 

see also: Ten-hour Timelag Fuel Moisture 

October 2014	 Page 173 
Glossary of Wildland Fire Terminology 

Terra Torch ® 

1 Device for throwing a stream of flaming liquid, used to facilitate rapid ignition during burn out 

operations on a wild fire or during a prescribed fire operation. 

synonym: Flame Thrower 

Terrorism 

1	 Any premeditated, unlawful act dangerous to human life or public welfare that is intended to 

intimidate or coerce civilian populations or governments. 

Test Fire 

1	 A prescribed fire set to evaluate such things as fire behavior, fire effects, detection performance, 

or control measures. 

Thermal Belt 

1	 An area of mountainous slope (characteristically the middle third), where the top of the radiation 

inversion intersects the slope. It typically experiences the least variation in diurnal temperatures 

and has the highest average temperatures and, thus, the lowest relative humidity. Its presence 

is most evident during clear weather with light wind. 

Thermal Imagery 

1 The display or printout of an infrared scanner operating over a fire. Also called infrared
 

imagery. 

see also: Infrared
 

Thin Layer 

1	 Layer of clouds whose ratio of dense sky cover to total sky cover is 1/2 or less. 

Thin Sky Cover 

1	 Sky cover through which higher clouds or the sky can be detected. 

Threat Fire 

1	 Any uncontrolled fire near to or heading toward an area under organized fire protection. 

Throw Out 

1 Soil pushed over the edge of a fireline by a tractor plow or dozer. 

see also: Berm
 

Thunderstorm 

1	 Localized storm characterized by one or more electrical discharge(s). 

Tie-In 

1	 Act of connecting a control line to another fireline or an intended firebreak. 

Time Delay Device 

1	 A device employed to allow a fire setter the opportunity to leave the scene prior to the ignition of 

the fire. 

Time in Service 

1	 With respect to maintenance time records, the time from the moment an aircraft leaves the 

surface of the earth until it touches at the next point of landing. 

Time Unit 

1	 Functional unit within the Finance/Administration Section responsible for recording personnel 

time and managing the commissary. 

October 2014	 Page 174 
 

 

Glossary of Wildland Fire Terminology 

Time Unit Leader (TIME) 

1 The ICS position responsible for supervising the Time Unit. Reports to the
 

Finance/Administration Section Chief. 

see also: Time Unit
 

Timelag (TL) 

1	 Time needed under specified conditions for a fuel particle to lose about 63 percent of the 

difference between its initial moisture content and its equilibrium moisture content. If conditions 

remain unchanged, a fuel will reach 95 percent of its equilibrium moisture content after 4 timelag 

periods. 

Time-Temperature Curve 

1	 Graph showing the increase in temperature at a specified point in a fire as a function of time, 

beginning with ignition and ending with burnout. 

Tinder 

1 Burnable organic material (duff, peat, rotten wood, etc.) with a high surface to volume ratio. 

Tips 

1	 Nozzle tips used to change orifice size of a hose stream. 

Tool and Equipment Specialist 

1	 Person responsible to the receiving/distribution manager for sharpening, servicing, and repairing 

hand tools. 

Torch 

1 Ignition and subsequent envelopment in flames, usually from bottom to top, of a tree or small 

group of trees. 

2 To set fire to property deliberately and maliciously. 

3 A professional firesetter-for-hire. 

Torching 

1 The burning of the foliage of a single tree or a small group of trees, from the bottom up. 

synonym: Candling
 

Total Fuel 

1	 All plant material both living and dead that can burn in a worst case situation. 

Total Mobility 

1	 The capability to move, position, and utilize established forces to meet existing and anticipated 

fire protection needs nationwide. 

Total Risk 

1	 Part of the National Fire Danger Rating System (NFDRS). Sum of lightning and human-caused 

risk values; cannot exceed a value of 100. 

Total Suspended Particulate Matter (TSP) 

1	 Particles emitted from a pollution source regardless of size. Federal and state ambient and 

emission standards exist for TSP. 

Touchdown Pad 

1	 That portion of a heliport or helispot where the helicopter lands. 

Toxic 

1	 Relating to a harmful effect by a poisonous substance on the human body by physical contact, 

ingestion, or inhalation. 

October 2014	 Page 175 
 

Glossary of Wildland Fire Terminology 

Toxic Substance 

1	 A chemical or mixture that may present an unreasonable risk of injury to health or the
 

environment. 

Tractor 

1	 A rubber tired or tracked rider-controlled automotive vehicle, used in wildland fire management 

for pulling a disk or a plow to construct fireline by exposing mineral soil. 

see also:	 Dozer
 

Plow Line
 

Tractor Plow
 

Tractor Plow 

1 Any tractor with a plow for constructing fireline by exposing mineral soil. Also as a resource for 

typing purposes, a tractor plow includes the transportation and personnel for its operation. 

see also:	 Dozer
 

Plow Line
 

Tractor
 

Traffic Pattern 

1	 Traffic flow that is prescribed for aircraft landing at, taxiing on, and taking off from, an airport. 

Usual components of a traffic pattern are upwind leg, crosswind leg, downwind leg, base leg, 

and final approach. 

Trail Drop 

1	 An unbroken line of retardant used for constructing a retardant line. 

Trailer 

1	 Combustible material, such as rolled rag, blankets and newspapers, or flammable liquid, used to 

spread fire from one area to others; usually used in conjunction with an incendiary device. 

Trainee 

1	 An individual who has met all required training and position experience for a specified position 

and is approved by their home unit's certifying official, to initiate a performance based training 

assignment in order to become qualified in the position. 

Trainer/Coach 

1	 A position-qualified individual who provides instruction to a trainee in the classroom, on-the-job, 

or on an incident. While many of the requirements of the trainer/coach are similar to the 

evaluator, it is important that the roles of training and evaluation remain separate. 

Training Officer 

1	 The chief or other officer under the agency or department responsible for organizing and
 

conducting a complete training program for the suppression agency. 

Training Specialist (TNSP) 

1	 Person responsible to the planning section chief for coordinating the use of trainees on the 

incident and for assuring that the trainees meet their training objectives and receive 

performance evaluation reports. 

Transfer of Command 

1	 The ICS management process in which the on-scene incident commander at a specified time 

hands off command responsibilities to the incident commander that will be taking over incident 

command. 

Transition 

1	 In the 1978 version of NFDRS, the herbaceous stage when herbaceous fuel moisture is
 

between 120% and 30%. 

October 2014	 Page 176 
 

 

Glossary of Wildland Fire Terminology 

Translational Lift 

1	 Lift that is gained when a helicopter translates from a hover into forward flight; additional lift 

increases with increasing airspeed and is derived by the rotor system moving into undisturbed 

air. 

Transport Wind Speed 

1	 A measure of the average rate of the horizontal transport of air within the Mixing Layer. May 

also be the wind speed at the final height of plume rise. Generally refers to the rate at which 

emissions will be transported from one area to another. 

see also:	 Mixing Layer
 

Ventilation Factor
 

Transportation Map 

1	 Base map of the planning unit showing all roads, trails, heliports, and airfields existing and 

programmed for construction. 

Travel Time 

1	 Compensable time en route to or from an emergency incident. 

Travel Time Map 

1	 Map showing the time required for the initial attack crew to reach various parts of a protection 

unit from specified positions. 

Trench 

1	 A small ditch often constructed below a fire on sloping ground (undercut or underslung line) to 

catch rolling material. 

Trigger Points 

see:	 Management Action Points 

Trough 

1	 An elongated area of relatively low atmospheric pressure, usually extending from the center of a 

low pressure system. 

Truck Trail 

1	 Substantial transportation route for fire suppression motor vehicles, built prior to a fire. Also 

called fire road. 

True Airspeed 

1	 Velocity of an aircraft in its flight path relative to the air through which it is moving. 

True Bearing 

1	 Bearing by true north rather than magnetic north. 

Turbulence 

1	 Irregular motion of the atmosphere usually produced when air flows over a comparatively 

uneven surface such as the surface of the earth; or when two currents of air flow past or over 

each other in different directions or at different speeds. 

Turn the Corner 

1	 Contain a fire along a flank of the fire and begin containing it across the head. Refers to ground 

or air attack. 

Turnaround Time 

1	 Time used by an air tanker or helitanker to reload and return to the fire. 

October 2014	 Page 177 
 

 

1 

Glossary of Wildland Fire Terminology 

Turnout Coat 

A coat with a fire resistant outer shell and a thermal and moisture barrier liner. Used primarily 

by structure firefighters. Also called fire coat. 

Two-Way Radio 

1 Radio equipment with transmitters in mobile units on the same frequency as the base station, 

permitting conversation in two directions using the same frequency in turn. 

Type 

1 Refers to resource capability. A Type 1 resource provides a greater overall capability due to 

power, size, capacity, etc., than would be found in a Type 2 resource. Resource typing provides 

managers with additional information in selecting the best resource for the task. 

- U -

Ultra High Frequency (UHF-FM) 

1	 Radio frequencies from 300 Megahertz (MHz) to 3,000 MHz with a normal range of less than 50 

miles. Radio frequency common to military aircraft and used in the logistics radio system. The 

most common frequencies used by fire and public safety are from 406 MHz to 512 MHz. 

Unacceptable Risk 

1	 Level of risk as determined by the risk management process which cannot be mitigated to an 

acceptable safe level. 

Uncontrolled Airport 

1	 Airport not having an approved agency with radio communications to direct aircraft take-offs and 

landings. 

Uncontrolled Fire 

1	 Any fire which threatens to destroy life, property, or natural resources, and (a) is not burning 

within the confines of firebreaks, or (b) is burning with such intensity that it could not be readily 

extinguished with ordinary tools commonly available. 

see also: Wildfire 

Underburn 

1 A fire that consume surface fuels but not the overstory canopy. 

see also: Understory Burning 

Undercut Line 

1 A fireline below a fire on a slope. Should be trenched to catch rolling material. Also called 

underslung line. 

see also: Cup Trench 

Understory Burning 

1 Prescribed burning under a forest canopy. 

see also: Underburn 

Unicom 

1	 VHF/AM aircraft radio frequencies assigned by the FAA for use in air-to-ground communications 

at uncontrolled airfields. The frequencies most commonly used are 122.8 MHz and 122.85 MHz. 

Unified Area Command 

1	 A unified area command is established when incidents under an area command are 

multijurisdictional. 

October 2014	 Page 178 
 

Glossary of Wildland Fire Terminology 

Unified Command 

1 In ICS, unified command is a unified team effort which allows all agencies with jurisdictional 

responsibility for the incident, either geographical or functional, to manage an incident by 

establishing a common set of incident objectives and strategies. This is accomplished without 

losing or abdicating authority, responsibility, or accountability. 

Unit 

1 The organizational element of an incident having functional responsibility for a specific activity in 

the planning, logistics, or finance/administration activity. 

Unity of Command 

1	 The concept by which each person within an organization reports to one and only one 

designated person. 

Unity of Effort 

1	 A command philosophy that encourages leaders to work together to find common ground and 

act in the best interest of those responding to the incident, the public, and the resources that are 

threatened. 

Unlined Fire Hose 

1	 Hose commonly of cotton, linen, or synthetic fiber construction without rubber tube or lining, 

often used for wildfires because of its light weight and self protecting (weeping) characteristics; 

such hose is attached to first-aid standpipes in buildings. At a specified flow, friction loss in 

unlined hose of a stated diameter is about twice that of lined fire hose. 

Unplanned Ignition 

1 The initiation of a wildland fire that was unplanned, regardless of cause. 

see also: Wildfire 

Upper Level (Cold) Low 

1	 (Upper Level Disturbance, Cold Low Aloft) A circulation feature of the upper atmosphere where 

pressure, at a constant altitude, is lowest. Winds blow counter-clockwise around the center in 

an approximately circular pattern. Upper level lows are usually quite small. The mechanics of 

these upper lows is such that a pool of cool moist air always accompanies their development. 

There is often no evidence of low pressure at the earth's surface. An upper low may exist 

above a surface high pressure system. 

Upper Level (Cold) Trough 

1	 (Trough, Trough Aloft, Upper Level [Cold] Low) An elongated area of relatively low pressure, at 

constant altitude, in the atmosphere. The opposite of an upper level ridge. Upper level troughs 

are usually oriented north-south with the north end open. That is, air currents moving from west 

to east around the earth flow around three sides of the trough then turn eastward rather than 

toward the west, as in the case of a closed circulation. A large upper level trough may have one 

or more small upper level closed low circulation systems within it. 

Upper Level High 

1	 (Upper High, High Aloft, Upper Level Ridge) A circulation feature of the upper atmosphere 

where pressure, at a constant altitude, is higher than in the surrounding region. Winds blow 

clockwise around an upper level high. Air in an upper level high is usually subsiding. This 

results in comparatively warm dry air with light winds over a large area. An upper level high 

may exist without there being high pressure at the earth's surface. 

October 2014	 Page 179 
 

 

Glossary of Wildland Fire Terminology 

Upper Level Ridge 

1	 (Upper Level High, Ridge Aloft) An elongated area of relatively high pressure, at a constant 

altitude, in the atmosphere. The opposite of an upper level trough. Upper level ridges are often 

oriented north-south, alternating between upper level troughs, however, during summer they 

may assume random orientations and vast dimensions. 

Urban Interface 

see:	 Wildland Urban Interface 

Use Level 

1	 The appropriate ratio of liquid foam concentrate to water recommended by the chemical 

manufacturer for each class of fire, usually expressed as a percent (such as 0.5%). 

Use of Wildland Fire 

1 Management of wildfire or prescribed fire to meet resource objectives specified in land/resource 

management plans. 

see also: Prescribed Fire 

Wildland Fire 

Useful Load 

1	 Maximum computed gross weight minus equipped weight of a helicopter. 

- V -

V Pattern 

1 Characteristics fire cone-shaped pattern left by a fire on a wall, at or near its point of origin. 

see also: V Pattern Indicators 

V Pattern Indicators 

1	 The overall "V" or "U" shape of the exterior perimeter of a fire. 

Values To Be Protected 

1	 Include property, structures, physical improvements, natural and cultural resources, community 

infrastructure, and economic, environmental, and social values. 

Values-At-Risk 

see:	 Values To Be Protected 

Vapor Suppression 

1	 Creating a seal with foam which prevents a release of flammable vapors from fuels. 

Variable 

1 Any changing characteristic; in statistics, a measurable characteristic of an experimental unit. 

Variable Ceiling 

1	 A ceiling of less than 3,000 feet (900 m) which rapidly increases or decreases in height by one 

or more reportable values during the period of observation. 

Variable Danger 

1	 Resultant of all fire danger factors that vary from day to day, month to month, or year to year 

(e.g., fire weather, fuel moisture content, condition of vegetation, variable risk) 

Variable Sky Condition 

1	 A sky condition that varies between reportable values of sky cover amounts during the period of 

observation. 

October 2014	 Page 180 
 

Glossary of Wildland Fire Terminology 

Variable Visibility 

1	 A condition when the prevailing visibility is less than 3 miles (5 km) and rapidly increases and 

decreases by one or more reportable values during the period of observation. 

Variable Wind Direction 

1	 Wind direction which varies by 60 degrees or more during the period of time the wind direction is 

being determined. 

Vectors 

1 Directions of fire spread as related to rate of spread calculations (in degrees from upslope). 

Vegetative Regeneration 

1	 Development of new aboveground plants from surviving plant parts, such as by sprouting from a 

root crown or rhizomes. Even if plants form their own root system, they are still genetically the 

same as the parent plant. 

Vegetative Reproduction 

1	 Establishment of a new plant from a seed that is a genetically distinct individual. 

Vehicle Fire 

1	 Fire originating in or on a vehicle or mobile equipment. 

Vent 

1	 The release of enclosed smoke and heat from a structure by creating openings in it, as by 

hacking a hole in the roof, to allow free passage of air. 

Ventilation Factor 

1 A numerical value relating the potential of the atmosphere to disperse airborne pollutants from a 

stationary source, calculated by multiplying the mixing height by the transport wind speed. 

see also: Mixing Layer 

Transport Wind Speed 

Ventilation Index 

1	 A measure of the volume rate of horizontal transport of air within the mixing layer, per unit 

distance, normal to the wind. Units are measured in square meters per second or knot-feet. 

Vertical Fuel Arrangement 

1	 Fuels above ground and their vertical continuity, which influences fire reaching various levels or 

vegetation strata. 

Vertical Temperature Profile 

1	 Plot of the actual dry-bulb temperature against height above the earth's surface, most commonly 

determined by a RAWINSONDE observation. 

Very High Frequency (VHF-AM) 

1	 Radio frequency range from 30 MHz to 299 MHz. The sub-bands most commonly used by fire 

are: 

VHF-FM Lo band: Frequency Modulation 30 MHz - 80 MHz, of which fire frequencies are 

between 30 MHz and 50 MHz. 

VHF-FM Hi band: Frequency Modulation 150 MHz - 174 MHz. This is the most widely used 

band by fire agencies. 

VHF-AM: Amplitude Modulation. This band is commonly referred to as the "Victor or VHF" band. 

The frequency range is from 118 MHz to 136 MHz. The only authorized use of this band is for 

aviation. The FAA controls and assigns all frequencies within this sub-band. 

October 2014	 Page 181 
 

Glossary of Wildland Fire Terminology 

VHF Omnidirectional Radio Range (VOR) 

1	 System of radio navigation in which any magnetic bearing relative to a special radio transmitter 

on the ground may be chosen and flown by an aircraft pilot. 

Vigor 

1	 A subjective assessment of the health of individual plants in similar site and growing conditions; 

or a more specific measure based upon a specific facet of growth, such as seed stalk or tiller 

production per plant or per unit area. 

Virga 

1	 Precipitation falling out of a cloud but evaporating before reaching the ground. 

Viscosity 

1	 Thickness of a liquid, the degree to which it resists flow. 

Viscous Water 

1	 Water that contains a thickening agent to reduce surface runoff; tends to cling to burning fuels 

and spread in layers that are several times thicker than plain water, thereby having an increased 

capacity to absorb heat, cool fuel, and exclude oxygen. Also called thickened water. 

Visibility 

1	 The greatest horizontal distance at which selected objects can be seen and identified, or its 

equivalent derived from instrumental measurements. 

Visible Area Map 

1	 Map showing the different classes of visible area covered by a lookout point or points; may 

differentiate between seen areas, indirectly visible areas, and blind areas, or only between seen 

areas and blind areas. Also called seen area map. 

see also: Seen Area 

Visual Flight Rules Conditions (VFR) 

1 Basic weather conditions prescribed for flight under Visual Flight Rules: ceiling above 1,000 feet 

(300 m) and flight visibility in excess of 3 miles (5 km). 

see also: Instrument Flight Rules Conditions 

Visual Greenness (VG) 

1 An NDVI-derived image of vegetation greenness compared to a very green reference such as a 

golf course. 

see also: Greenness Factor 

Visual Range 

1 Maximum distance at which a given object can just be seen by an observer with normal vision. 

Visual Resource Management (VRM) 

1	 The inventory and planning actions taken to identify visual values and to establish objectives for 

managing those values; and the management actions taken to achieve the visual management 

objectives. 

Visual Resources 

1	 The visible physical features on a landscape (e.g., land, water, vegetation, animals, structures 

and other features). 

Volatile 

1	 Readily changeable into vapor at low temperatures. 

Volatiles 

1	 Readily vaporized organic materials which, when mixed with oxygen, are easily ignited. 

October 2014	 Page 182 
 

Glossary of Wildland Fire Terminology 

Volunteer Fire Company 

1	 A fire department company or a response unit, the members of which are not paid. 

Volunteer Fire Department (VFD) 

1	 A fire department of which some or all members are unpaid. 

Volunteer Firefighter 

1	 Legally enrolled firefighter under the fire department organization laws who devotes time and 

energy to community fire service without compensation other than Worker's Compensation or 

other similar death and injury benefits. 

Vortex Turbulence 

1	 Miniature whirlwinds trailing from the wingtips of any aircraft in flight. Vortex will be in the form of 

a horizontal whirlwind with velocities up to 25 mph (40 km) per hour or more. Also created by 

action of rotor blades on helicopters; these whirlwinds tend to move downward toward the 

ground. If an aircraft flies low over a fire, vortices may reach the ground and suddenly cause 

violent and erratic fire behavior. 

- W -

Walk Test 

1	 The walk test is designed to determine the ability to carry out light duties. It consists of a onemile test with no load that approximates an aerobic fitness score of 35. A time of 16 minutes, the 

passing score for this test, ensures the ability to meet emergency and evacuate to a safety 

zone. 

see also: Work Capacity Test 

Warm Front 

1	 The leading edge of a relatively warm air mass which moves in such a way that warm air 

replaces colder air that moves away from a region. Winds associated with warm frontal activity 

are usually light and mixing is limited. The atmosphere is relatively stable when compared to 

cold front activity. 

Water Bar 

1	 A shallow channel or raised barrier, e.g., a ridge of packed earth or a thin pole laid diagonally 

across the surface of a road or trail so as to lead off water, particularly storm water. (Frequently 

installed in firelines on steep slopes to prevent erosion.) 

Water Expansion Pumping System (WEPS) 

1	 Apparatus utilizing an air compressor and positive displacement pump coupled to the same 

engine, plumbed to a non-pressurized tank, for producing foam. The operation involves injecting 

compressed air into a liquid stream containing a suitable foaming agent. 

Water Expansion System (WES) 

1	 Apparatus utilizing a pressurized tank, hose, and nozzle for producing foam by injection of 

compressed air or gas into a liquid stream downstream from the pumping source. The liquid 

stream must contain a suitable foaming agent. 

Water Hammer 

1	 A force created by the rapid acceleration or deceleration of water, commonly created by 

opening or closing a valve too quickly. Pressures developed in a water hammer, proportional to 

the mass multiplied by the square of the velocity, can damage a pipe or hose. 

October 2014	 Page 183 
 

 

 

Glossary of Wildland Fire Terminology 

Water Resources Specialist 

1	 Person responsible to the planning section chief for collecting information of water resources in 

and adjacent to the incident area, determining water use requirements of firefighting resources, 

and providing input to the Incident Action Plan about available water resources and/or 

anticipated shortages. 

Water Source 

1	 Any strategically located supply of water that is readily available for pumps, tanks, trucks, 

helicopters, or fire camp use. 

Water Supply Map 

1	 A map showing location of supplies of water readily available for pumps, tanks, trucks, camp 

use, etc. 

Water Tender 

1	 Any ground vehicle capable of transporting specified quantities of water. 

Water Thief 

1	 A type of bleeder valve designed for installation at convenient points in hose lines to permit 

drawing off water for filling backpack pumps or other use without interfering with pump or nozzle 

operation. 

Wave 

1	 A disturbance that transfers energy from one point to another point and may take the form of a 

deformation of pressure or temperature. In the atmosphere such disturbances may result in 

major storms or merely result in changes in cloud, wind and temperature conditions. 

Development of a wave on a front usually slows the advance of the front due to transfer of 

energy to the wave development and movement. 

Weather Advisory 

1	 In aviation forecasting, an expression of hazardous weather conditions not predicted in the zone 

weather forecast, as they affect the operation of air traffic. 

Weather Information Management System (WIMS) 

1 A centralized weather data processing system at which daily fire danger ratings are produced. 

Weather Observer 

1	 Person responsible to the situation unit leader for collecting current weather data and 

information at the incident and providing them to an assigned meteorologist, fire behavior
 

specialist, or the Situation Unit Leader. 

Weighted Monthly Occurrence 

1	 Part of the National Fire Danger Rating System (NFDRS). Number used to determine seasonal 

risk class for a protection unit, calculated by multiplying peak monthly average by two and 

adding seasonal monthly average. 

Western Regional Climate Center (WRCC) 

1	 One of six NOAA regional climate centers in the United States at which all hourly observations 

from all RAWS and many AWS are archived. 

Wet Foam 

1	 A low expansion foam type with few and varied bubbles and rapid drain time which is used for 

rapid penetration and fire extinguishment. 

Wet Line 

1	 A line of water, or water and chemical retardant, sprayed along the ground, and which serves as 

a temporary control line from which to ignite or stop a low-intensity fire. 

October 2014	 Page 184 
 

 

Glossary of Wildland Fire Terminology 

Wet Storage 

1 Fire retardants mixed with water and stored in tanks at air attack bases for immediate use by air 

tankers. 

see also: Dry Storage 

Wet Water 

1	 Water with added chemicals, called wetting agents, that increase water's spreading and
 

penetrating properties due to a reduction in surface tension. 

Wet-bulb Depression 

1	 The difference between the wet and dry-bulb temperatures recorded by a psychrometer; used in 

conjunction with the dry-bulb temperature as a measure of the relative humidity of the air. 

Wet-bulb Temperature 

1	 The lowest temperature to which air can be cooled by evaporating water into it at a constant 

pressure when the heat required for evaporation is supplied by the cooling of the air. It is 

measured by the wet bulb thermometer, which usually employs wetted wicking on the bulb as a 

cooling (through evaporation) device. 

Wet-bulb Thermometer 

1	 In a psychrometer, the thermometer with its bulb covered with a jacket of clean muslin which is 

saturated with distilled water before an observation. 

Wetting Agent 

1	 A chemical that when added to water reduces the surface tension of the solution and causes it 

to spread and penetrate exposed objects more effectively than the untreated water. 

Wetting Rain 

1	 A widespread rain that over an extended period of time significantly reduces fire danger. Onetenth of an inch may be sufficient to reduce fire danger in grass fuel models. One half inch may 

be necessary for timber fuels under closed canopies. 

Wheelbase 

1	 The distance from the centerline of the front axle to the centerline of the rear axle. For a tandem 

rear axle vehicle the center line is midpoint between the centers of the two rear axles. 

Widow-Maker 

1	 A loose limb or top or piece of bark lodged in a tree, which may fall on anyone working beneath 

it. 

Wildfire 

1	 An unplanned, unwanted wildland fire including unauthorized human-caused fires, escaped 

wildland fire use events, escaped prescribed fire projects, and all other wildland fires where the 

objective is to put the fire out. 

see also:	 Prescribed Fire
 

Uncontrolled Fire
 

Wildland Fire
 

Wildfire Suppression 

1	 An appropriate management response to wildfire or prescribed fire that results in curtailment of 

fire spread and eliminates all identified threats from the particular fire. 

Wildland 

1	 An area in which development is essentially non-existent, except for roads, railroads, 

powerlines, and similar transportation facilities. Structures, if any, are widely scattered. 

October 2014	 Page 185 
Glossary of Wildland Fire Terminology 

Wildland Fire 

1 Any non-structure fire that occurs in vegetation or natural fuels. Wildland fire includes prescribed 

fire and wildfire. 

see also: Prescribed Fire 

Wildfire 

Wildland Fire Assessment System (WFAS) 

1 An internet-based information system, providing national views of weather and fire potential, 

including national fire danger and weather maps and satellite-derived greenness maps. 

Wildland Fire Investigator (INVF) 

1	 An individual responsible for identifying and securing a wildfire's origin and determining the 

probable cause and documenting causal factors in a case report. INVF may not be directly 

assigned to an incident, working in conjunction with incident management as not to interfere 

with incident operations, while ensuring that an incident does not impede the on-scene 

investigation. 

Wildland Fire Leadership Principles 

1	 Eleven principles describing tangible behaviors that reflect and demonstrate the wildland fire 

leadership values. The eleven principles are:

 1. Be proficient in your job.

 2. Make sound and timely decisions.

 3. Ensure tasks are understood, supervised, and accomplished.

 4. Develop your subordinates for the future.

 5. Know your subordinates and look out for their well-being.

 6. Keep your subordinates informed.

 7. Build the team.

 8. Employ your subordinates in accordance with their capabilities.

 9. Know yourself and seek improvement. 

10. Seek responsibility and accept responsibility for your actions. 

11. Set the example. 

see also: Wildland Fire Leadership Values
 

Wildland Fire Leadership Values 

1	 Three guiding values that should be the basis for the decisions that leaders make. The three 

values are:

 1. Duty – How a leader values their job. Duty begins with everything required by law and policy, 

but is much more than that. A leader commits to excellence in all aspects of their professional 

responsibility so that when the job is done they can look back and say, "I couldn't have given 

any more."

 2. Respect – How a leader values their co-workers. Respect for the individual forms the very 

basis for the rule of law in America. This value reminds leaders that those who follow are their 

greatest resource. Not all followers will succeed equally, but they all deserve respect.

 3. Integrity – How a leader values himself or herself. An individual cannot be in charge of others 

unless they are in charge of their own actions. People of integrity separate what is right from 

what is wrong and act according to what they know is right, even at personal cost. 

see also: Wildland Fire Leadership Principles 

Wildland Fire Management Information (WFMI) 

1	 A Web site providing current weather and lightning data, as well as historic fire occurrence data. 

NWCG Unit Identifiers are also maintained on the site. 

Wildland Fire Module 

1	 A group of 7-10 highly skilled personnel specifically associated with the planning and 

implementation of planned and unplanned wildland fire and hazardous fuels treatments. Maybe 

classified as a Type 1 or Type 2 dependent on qualifications and experience. 

October 2014	 Page 186 
 

 

 

Glossary of Wildland Fire Terminology 

Wildland Fire Serious Accident 

1	 Any accident where one or more fatalities occur and/or three or more personnel are inpatient 

hospitalized as a direct result, or in support of wildland fire suppression or prescribed fire 

operations. Accident may result in substantial property or equipment damage of $250,000 or 

more. 

Wildland Urban Interface (WUI) 

1	 The line, area, or zone where structures and other human development meet or intermingle with 

undeveloped wildland or vegetative fuels. Describes an area within or adjacent to private and 

public property where mitigation actions can prevent damage or loss from wildfire. 

see also: I-Zone 

Wind 

1	 The horizontal movement of air relative to the surface of the earth. 

Wind Direction 

1	 Compass direction from which wind is blowing. 

Wind Profile 

1	 A chart of wind speed in relation to height, most commonly determined by a pilot balloon
 

observation. 

Wind Shear 

1	 A variation in wind speed and/or direction in a layer of the atmosphere or between layers. The 

variation may be in the horizontal or vertical dimensions and may result in significant turbulence 

depending upon the magnitude of the wind speed/direction differences. A strong wind shear 

may act like an inversion and inhibit plume rise. It may also fracture the smoke plume, not 

allowing smoke to rise much above terrain levels. A strong horizontal anticyclonic shear results 

in downward motion and may bring smoke aloft to the surface. 

Wind Shift 

1	 For aviation purposes, a change in the average wind direction of 45 degrees or more which 

takes place in less than 15 minutes if the wind speed during this period is 6 knots (3 m/s) or 

greater. 

2	 For ground observation purposes, a change of at least 45 degrees in the direction of a
 

significant wind, which occurs in a relatively short time frame. 

Wind Speed 

1	 Wind, in miles per hour, measured at 20 feet above open, level ground or as adjusted to meet 

this standard to compensate for height of ground cover, uneven ground, and nearby 

obstructions. 

2	 (NFDRS) Wind, in mph, measured at 20 feet above ground, or above the average height of 

vegetation, and averaged over at least a 10-minute period. Also called wind velocity. 

Wind Vectors 

1	 Wind directions used to calculate fire behavior. 

Wind-driven Wildland Fire 

1	 A wildland fire that is controlled by a strong consistent wind. 

Windfall 

1	 Tree that has been uprooted or broken off by wind. 

Windrow Burning 

1	 Burning slash that has been piled into long continuous rows. Also includes wildfire in vegetation 

planted to protect improvements or agriculture. 

October 2014	 Page 187 
 

Glossary of Wildland Fire Terminology 

Winds Aloft 

1	 Generally, wind speeds and wind directions at various levels in the atmosphere above the 

domain of surface weather observations. 

Windspeed Meter 

1	 A handheld device which indicates wind speed, usually in miles per hour. 

Woody Fuel Moisture 

1	 In NFDRS, a calculated value representing the approximate moisture content of the live woody 

vegetation in the rating area expressed as a percentage of the oven dry weight of the sample. 

see also:	 Herbaceous Fuel Moisture
 

Measured Woody Fuel Moisture
 

Woody Vegetation Condition
 

Woody Vegetation Condition 

1 Part of the National Fire Danger Rating System (NFDRS). A code reflecting the moisture 

content of the foliage and small twigs [less than 1/4 inch (0.6 cm)] of living woody plants. 

see also: Woody Fuel Moisture 

October 2014	 Page 188 
Glossary of Wildland Fire Terminology 

Work Capacity Test (WCT) 

1	 A family of tests to determine firefighter physical capabilities. 

Work capacity tests are used to ensure that persons assigned to fire activities are physically 

capable of performing the duties of wildland firefighting and to meet National Wildfire 

Coordinating Group (NWCG) standards for wildland firefighters (Wildland Fire Qualification 

Subsystem Guide 310-1, NWCG, 1993). The WCT is a family of tests to determine firefighter 

physical capabilities at three levels: 

Arduous:
 

"Duties involve field work requiring physical performance calling for above-average endurance 

and superior conditioning. These duties may include an occasional demand for extraordinarily 

strenuous activities in emergencies under adverse environmental conditions and over extended
 

periods. Requirements include running, walking, climbing, jumping, twisting, bending, and lifting 

more than 50 pounds; the pace of work typically is set by the emergency condition."
 

Moderate:
 

"Duties involve field work requiring complete control of all physical faculties and may include
 

considerable walking over irregular ground, standing for long periods, lifting 25 to 50 pounds, 

climbing, bending, stooping, squatting, twisting, and reaching. Occasional demands may be
 

required for moderately strenuous activities in emergencies over long periods. Individuals
 

usually set their own work pace."
 

Light:
 

"Duties mainly involve office-type work with occasional field activity characterized by light 

physical exertion requiring basic good health. Activities may include climbing stairs, standing, 

operating a vehicle, and long hours of work, as well as some bending, stooping, or light lifting. 

Individuals almost always can govern the extent and pace of their physical activity"
 

Each performance level has its own unique Work Capacity Test:
 

Pack Test:
 

The pack test is a job-related test of the capacity for arduous work. It consists of a 3-mile hike
 

with a 45-pound pack over level terrain. A time of 45 minutes, the passing score for the test, 

approximates an aerobic fitness score of 45, the established standard for wildland firefighters.
 

Field Test:
 

The field test is a job-related test of work capacity designed for those with moderately strenuous
 

duties. It consists of a 2-mile hike with a 25-pound pack. A time of 30 minutes, the passing
 

score, approximates an aerobic fitness score of 40.
 

Walk Test:
 

The walk test is designed to determine the ability to carry out light duties. It consists of a 1-mile
 

test with no load that approximates an aerobic fitness score of 35. A time of 16 minutes, the
 

passing score for the test, ensures the ability to meet emergencies and evacuate to a safety 

zone. 

Work/Rest Ratio 

1	 An expression of the amount of rest that is required for each hour an individual is in work status. 

Current NWCG guidelines require one hour of rest for every two hours in work status. 

Woven Jacket Fire Hose 

1	 Fire hose of conventional construction, woven on looms from fibers of cotton or synthetic fibers. 

Most fire department hose is double jacketed (i.e., it has an outer jacket protecting the inner one 

against wear and abrasion). 

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1 

Glossary of Wildland Fire Terminology 

Wye 

1 A hose connection with two outlets permitting two connections of the same coupling diameter to 

be taken from a single supply line. 

see also: Reversible Siamese 

Siamese 

- Z -

Zone Weather Forecast 

A portion of the general fire weather forecast issued on a regular basis during the normal fire 

season specifically to fit the requirements of fire management needs; i.e., time, areas, and 

weather elements. These zones or areas are a combination of administrative and climatological 

areas, usually nearly the size of an individual forest or district. 

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