Fire and Rescue Service Wildfire Operational Guidance

Access

A point of entry and exit and/or route to an incident location.

Accelerant

Material used to initiate or increase the spread of a fire. This will often be a flammable liquid.

Aerial attack

A fire suppression operation involving the use of aircraft to release water or retardant on or near a wildfire. An aerial attack can be:

Direct attack (aerial)

• Head attack (aerial)
• Tail attack (aerial)

Indirect attack (aerial)

• Flank attack (aerial)
• Parallel attack (aerial

Aerial operations

Any manoeuvre completed by an aircraft in support of wildfire suppression activities, inclusive of:

• direct attack through drops of water or retardant
• indirect attack through retardant drops
• cargo drops of supplies
• aerial observation and reconnaissance

Aerial reconnaissance

Use of aircraft for conducting preliminary surveys of a wildfire to gather information on:

• fire behaviour
• topography and fuel types
• potential hazards and high risk areas
• potential windows of opportunity
• safety of ground personnel

The information gathered from aerial reconnaissance will be communicated to the Incident Commander to assist in the decision-making process.

All Terrain Vehicle (ATV)

Any motorised vehicle designed to travel on four low pressure tires on unpaved surfaces, having a seat designed to be straddled by the operator and handlebars for steering control.^[1]

ATVs can be classified into two categories:

• Type I - designed for transporting one operator.
• Type II - designed for transporting one operator and one passenger.

Anabatic wind

Upslope winds. Anabatic winds occur when daytime solar radiation heats air at lower elevations causing it to flow upslope.

Anchor Point

A location on the landscape which is strong enough to act as barrier to fire spread. The commencement of suppression operations from an anchor point ensures that a wildfire cannot escape from an area of containment which could threaten the success of the operation and/or the safety of suppression personnel. It may be necessary for anchor points to be strengthened before use or even created by hand or machine. The creation of an anchor point is sometimes a key element included within the LACES safety protocol.

Area ignition

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. ^[2]

Area of Special Scientific Interest

A statutory designation in Northern Ireland relating to areas of land that have been identified as being of the highest degree of conservation value.

Area of origin

General geographical location within a fire scene where the point of ignition is believed to be located.

Arson

The wilful or malicious burning of a fuel with criminal intent to cause damage.

Assigned resources

Resources that have been allocated work tasks at a wildfire incident.

Assignment

A task allocated to an individual or team to complete.

Aspect

The direction a slope faces in relation to the sun.^[3] Aspect is a force of alignment.

Attack a Fire

A generic term for the various methods that can be used to suppress a fire or parts of a fire, including:

• Direct attack - An offensive fire suppression tactic which involves an attack being made at or near the fires edge. This technique normally relies on the use of hand tools and or water.
• Indirect attack - Any suppression methods implemented away from the fire edge.
• Aerial attack - Fire suppression operation involving the use of aircraft to drop water or retardant on or near a wildfire.
• Flank attack - Attacking the fire along the flank or both flanks simultaneously.
• Parallel attack - Method of fire suppression in which a control line is constructed approximately parallel to and some distance away from the fire edge.

Aerial Fuels

Any fuel found at a height of more than 3.5 metres above the ground surface.

Aerial Resources

Aircraft including helicopters, aeroplanes and drones that can be used to attack the fire or observe its development. It also includes supporting personnel and equipment.

Anemometer

An instrument that measures wind speed.

Available Fuels

The proportion of the total fuel that would burn under specified burning and fuel conditions.

Back burn

An operational burn ignited along the inner edge of a control line to consume the fuel in the path of an advancing wildfire or to change the direction of force of the wildfire's convection column.

Backing Fire

A lower intensity fire or part of a fire which burns against the wind and/or down slope.

Baseline

The initial line of fire ignited along a control line to contain and control subsequent burn operations.

Bearing

The horizontal direction to or from any point, usually measured clockwise from true north, or some other reference point, through 360^[4] degrees.

Beaufort Wind Scale

A system for estimating wind speeds based on observation of visible wind effects. A series of descriptions of visible wind effects upon land objects or sea surfaces is matched with a corresponding series of wind speed ranges, each being allocated a Beaufort number.^[5]

Black Area

An area of fuel that is black in appearance because some or all of the fuel has been burnt. A black area may support a second burn if some fuel remains and this could represent a safety risk to suppression personnel.

Blind area

An area in which neither the ground nor its vegetation can be seen from an observation point.

Bog

A permanently saturated area of spongy ground with poor drainage. Bogs are usually found in upland areas experiencing cool temperatures and high rainfall. Slow decomposition of the plants found within bogs leads to the formation of peat.

Breakout

The escape of a fire from an area of containment

Briefing

A meeting during which relevant information is exchanged

Broadleaves

Trees that are characterised by their broad leaves, most of which are deciduous.

Build Up

a) A sustained increase in fire intensity

b) An accumulation of fuel available to burn

Burn

a) To be on fire.

b) An area of fuel consumed or partly consumed by a fire.

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

d) A managed fire (i.e. an operational burn or prescribed burn)

Burn plan

A pre-determined strategic scheme or programme of activities which is formulated in order to safely and effectively accomplish the objectives of a managed burn. A burn plan will outline the selection of tactics, selection of resources, resource assignments and how performance will be monitored during a managed burn. It should be noted that a burn plan may need to be dynamic to take into account any changes in conditions or circumstances.

Burn Crew/team

A group of individuals with the collective competencies to safely and effectively carry out an operational burn.

Burning Conditions

The state of the combined components of the fire environment that influence fire behaviour within available fuels. Burning conditions are usually specified according to the factors of aspect, weather, slope/topography, and fuel type and load.

Burning Out

The intentional burning of parcels of fuel to prevent fire spread. This is normally carried out to consume fuel between a control line and the fire edge.

Burning Period

The dates/months of the year when land management burning is legally permitted.

Burning regulations

Rules and restrictions concerning the use of operational burns as a fire suppression tactic.

Canopy

The upper layer of aerial fuels which will contain the crowns of the tallest vegetation present (living or dead).

Catch trench

A small ditch constructed below a fire on sloping ground to catch burning material rolling down slope.

Cause of Fire

The sequence of events and actions that brings an ignition source into contact with materials first ignited which leads to sustained combustion.^[6] For statistical purposes, causes of fire are usually grouped within a standard classification.

Centre burn

An ignition technique where a fire or a number of fires are ignited in the middle of an area of fuel. The intention of a centre burn is to create a strong convection plume that allows subsequent ignitions to be lit drawing the resulting fires inwards, normally away from any existing control lines.

Chain of command

The line of authority and responsibility along which operational orders are passed. Also commonly referred to as "line of command".

Check in

The process whereby resources first report to an incident.

Clean burn

A fire that consumes all vegetation and litter above the ground exposing the mineral soil.

Cloud types

A visible body of fine water droplets or ice particles suspended in the atmosphere. There are a significant number of different types of clouds; however, there are three key cloud types that are particularly important for wildfire suppression because they can be used as a visual indicator of atmospheric stability:

• Stratus clouds - low altitude (below 6,000 feet) clouds with a flat or sheet-like appearance which develop within a stable layer of the atmosphere.
• Cumulus clouds - clouds with strong vertical development (below 6,000 feet) which develop within an unstable layer of the atmosphere.
• Cumulonimbus clouds - clouds with very strong vertical development which develop within an unstable layer of the atmosphere. The base of cumulonimbus clouds is near to ground level and they can extend vertically beyond 50,000 feet.
• Fog - A cloud with its base on the ground surface.

Coarse fuels

Fuels that are more than 6mm in diameter. Due to their size and shape they burn more slowly and ignite less readily than finer fuels. Examples of coarse fuels include thick stems, logs, and branches. Coarse fuels can either be living or dead.

Condensation

The process by which a gas is transformed to a liquid.

Control Line

An inclusive term for all constructed or natural barriers and treated fire edges used to control a fire.^[7]

Combustibility

Relative ease of fire spread within a fire environment.

Combustion

The rapid oxidation of fuel in which heat and usually flame are produced

Compactness

The density of fuel particles. Compactness can influence ignition and fire behaviour

Competency

When a person has the authority and sufficient technical knowledge, training and experience to carry out their assigned tasks safely and effectively.

Command

The authority of an agency to direct and control resources. Command is delegated to an individual.

Condition of Vegetation

Stage of growth or degree of flammability of vegetation that forms part of a fuel complex. This will be dependent upon time of year, amount of curing and weather conditions.

Coniferous trees

Trees that are characterised by their needle- or scale-like leaves. Most conifers are evergreen.

Conduction

The transfer of thermal energy by direct contact.

Containment

An area of a fire where control has been established and no breakout is anticipated.

Contingency plan

A pre-prepared alternative plan which can be implemented if circumstances change.

Controlled fire

A fire with a secure perimeter, where no breakouts are anticipated.

Control Line

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

Contour line

A line on a map connecting points of equal elevation.

Convection

The transfer of heat by the movement of a gas or liquid. In meteorology, convection is the predominantly vertical movement of warmed air.

Convection Column

A rising column of pre-heated smoke, ash, particles and other debris that is produced by a fire.

Convection driven fire

A fire that is spread predominately by the intensity of the convection plume.

Cool fire

A low intensity fire or part of a fire.

Cooperating agency

Any organisation supplying resources to assist with the implementation of a fire suppression plan. A cooperating agency differs from a partner agency in the sense that it only comes to the assistance of a suppression agency when a wildfire occurs.

Co-ordinates

Alphanumeric characters that are used to describe the precise geographic location of a point on the earth's surface.

Counter burn

A planned operational burn which is ignited to burn into a wildfire and to take advantage of in-drafts towards the fire front. Alphanumeric characters that are used to describe the precise geographic location of a point on the earth's surface.

Creeping Fire

A slow burning fire with low flame activity. This type of fire may occur due to the condition of vegetation, fuel type or because a fire is burning out of alignment.

Crew

The term for a fire service unit consisting of a number of personnel.

Critical Point

This is a point in time or space when/where there will be a significant influence on fire spread, rate of spread and/or fire intensity.

Crown

The upper foliage of trees and shrubs, normally containing large amounts of fine fuels.

Crown fire/Crowning

When a fire burns freely in the upper foliage of trees and shrubs. There are three different types of crown fires:

• Active Crown Fire - A fire that advances as a wall of flame engulfing all surface and aerial fuels.
• Independent Crown Fire - A fire that advances through aerial fuels only.
• Intermittent Crown Fire - A surface fire involving torching behaviour but without sustained crowning activity. Rate of spread is controlled by the surface fire.

Curing

A process that leads to the reduction in moisture content of dead vegetation.^[9] This usually causes the vegetation to turn brown in appearance.

Dead fuels

Fuels with no living tissue. The moisture content of dead fuels is mostly controlled by external weather conditions, for instance, relative humidity, precipitation, temperature, and solar radiation.

Debris fuels

Dead and dying fuel, consisting of both fine and coarse fuels, and inclusive of twigs and any vegetation. Debris is usually found lying on the ground but can also be found at various levels within the vertical arrangement of fuels.

Deep-seated fire

An established ground fire burning 0.5 metres or more below the surface. This type of ground fire is particularly challenging to extinguish.

Depth of burn

The vertical reduction in surface and ground fuels due to consumption by fire.

Dew

The moisture which collects in small droplets on the surface of vegetation through the process of condensation. Dew predominantly forms at night.

Dew point

The temperature at which air must be cooled in order for atmospheric saturation to occur and, subsequently, for dew to form. Dew point can therefore be used as a measure of the moisture content of the air.

Direct Attack

An offensive fire suppression tactic which involves an attack being made at or near the fires edge. This technique normally relies on the use of hand tools and or water.

Drip Torch

A hand tool used to drop flaming fuel onto the ground to intentionally ignite a fire as part of an operational or prescribed burn.

Drought

A prolonged period of abnormally low precipitation within a particular area.

Duff

A surface fuel consisting of partly or fully decomposed organic material lying on the mineral soil.

Dynamic risk assessment

The continuous process of identifying hazards, assessing risk, taking action to eliminate or reduce risk, monitoring and reviewing, in the rapidly changing circumstances of an operational incident.^[10]

Elevated fuels

Any fuel found at a height of 1.5-3.5 metres. The presence of elevated fuels will increase the risk of vertical fire spread into aerial fuels and the canopy.

Elevation

Height above sea-level.

Escape plan

A predetermined list of actions to be enacted in the event of unforeseen hazardous circumstances (for instance, an unexpected change in fire behaviour). An escape plan must include an escape route. The development of an escape plan is a key element of the LACES Safety Protocol.

Escape route

A pre-planned route to be taken in the event of unforeseen hazardous circumstances (for instance, an unexpected change in fire behaviour). An escape route is an important part of an escape plan and is a key element of the LACES Safety Protocol.

Evacuation

The removal of people from dangerous or potentially dangerous areas and their relocation to safe areas.

Extinction

The ceasing of the combustion process, either naturally or as a result of suppression activities.

Extreme fire behaviour

Fire behaviour that becomes erratic or difficult to predict due to its rate of spread and/or flame length. This type of fire behaviour often influences it environment.

Fine fuels

Fast-drying dead fuels which are less than 6mm in diameter. Fine fuels ignite readily and are rapidly consumed by fire when dry. Examples of fine fuels include: grass, leaves, ferns, mosses, pine needles and small twigs. When dried, fine fuels are referred to as flash fuels.

Fine fuel moisture

The moisture content of fast-drying fuels. Measurement of moisture content will indicate the relative ease of ignition and flammability of a fine fuel.

Fire Environment

The surrounding conditions, influences, and modifying forces of topography, fuel, and weather that determine fire behaviour, fire effects and fire impact.

Fingers of Fire

An elongated burned area projecting from the main body of the fire resulting in an irregular fire perimeter. The pattern on the ground may resemble fingers on a hand, hence the name.^[11]

Fingers of fire ignition

An ignition pattern which involves igniting lines of fire at right angles to a control line and parallel to the wind.

Fire activity

Description of a fire based on an assessment of visible evidence, including the rate of spread, flame length, fire severity, and fire behaviour.

Fire analysis

Process of reviewing the behaviour and effects of a specific fire or group of fires and/or the actions taken to suppress it/them.

Fire behaviour

The reaction of a fire to the influences of fuel, weather, and topography. Different types of fire behaviour include:

• Smouldering fire - A fire burning without flame and with minimal rate of spread.
• Creeping fire - A fire with a low rate of spread and generally with a low flame length.
• Running fire - A fire with a high rate of spread.
• Torching - A single tree or small parcel of trees that burn from the base through the surface and aerial fuels and into the canopy of the vegetation.
• Spotting - fire behaviour where sparks and hot burning embers are transported by the wind or convection column to land beyond the fire perimeter resulting in spot fires.
• Crowning - When a fire burns freely in the upper foliage of trees and shrubs.

Fire behaviour forecast

A prediction of probable fire behaviour to be used to inform fire suppression operations.

Firebrand

Particles of ignited fuels that are carried by the wind or the air currents of a convection plume.

Firebreak

An area on the landscape where there is a discontinuity in fuel which will reduce the likelihood of combustion or reduce the likely rate of fire spread.

Fire concentration

The number of fires per unit area for a given period.

Fire damage

The loss that is caused by the fire. This loss will normally include financial costs, but will also include other direct and indirect costs to the environment and society.

Fire danger

A general term used to express an assessment of both fixed and variable factors of the fire environment that determine the ease of ignition, rate of spread, difficulty of control, and impact. Fire danger is often expressed as an index.^[12]

Fire danger index

A quantitative indicator of fire danger, expressed either in a relative sense or as an absolute measure. Fire danger indexes are often used to guide fire management activities.

Fire ecology

The study of the relationships and interactions between fire, living organisms and the environment.

Fire edge

Any section of the fire perimeter.

Fire effects

The physical, biological, and ecological impacts of fire on the environment. ^[13]

Fire environment

The surrounding conditions, influences, and modifying forces of topography, fuel, and weather that determine fire behaviour, fire effects and impact.

Fire fighting chemicals

Substances that have the ability to prevent, reduce or inhibit combustion. They can be applied from the air or from the ground and may be applied directly onto a fire or an area of unburned fuel.

Common types of fire fighting chemicals include:

• Foam - a mass of bubbles formed by mixing specific proportions of air with water and a foam concentrate. It is can be applied in order to smother and cool parts of a fire and/or to prevent ignition within a fuel.
• Gels - A chemical which is added to water to make it thicken. When used as an extinguishing agent the mixture is able to absorb more heat than water and sticks to the surface of the fuel.
• Wetting agents - which act to decrease the surface tension of water and therefore enable greater penetration into fuels.
• Retardants - a group of chemicals that are usually mixed with water which have the ability to reduce or inhibit combustion either in the long or short term:
• Long term retardants - have the ability to reduce or inhibit combustion even after the water that they contain has evaporated.
• Short term retardants - are primarily used to inhibit combustion through the more immediate cooling and/or smothering of a fire.

Fire footprint

Outer shape of the fire perimeter at a given point in time.

Fire front

Any part of the fire perimeter that displays continuous flaming combustion.

Fire growth

The evolution of a fire from ignition to self-sustaining propagation and its movement through available fuels.

Fire history

The reconstruction and interpretation of the chronology of wildfire occurrence and the causes and impacts of wildfires within a specified area.

Fire intensity

The rate at which a fire releases energy in the form of heat at a given location and at a specific point in time, expressed as kilowatts per metre (kW/m) or kilojoules per meter per second (kJ)

Fire investigation

The process of determining the origin, cause, and development of a fire.^[14]

Fire management Plan

A plan detailing predetermined fire suppression strategies and tactics to be implemented following the occurrence of a wildfire within a particular area.

Fire model

A computer program which will predict or reconstruct fire behaviour and rate of spread of a fire from a point of ignition or area of origin.

Fire perimeter

The entire outer boundary of a fire.

Fire prediction system

A method or tool used to forecast future behaviour of a fire.

Fire prevention

A collective term for all proactive activities that are implemented with the aim of reducing the occurrence, severity and spread of wildfires.

Fire regime

The pattern of fire occurrence, fire frequency, fire seasons, fire size, fire intensity, and fire type that is characteristic of a particular geographical area and/or vegetation type.

Fire restrictions

Measures taken to limit or prevent particular activities to reduce the likelihood of a wildfire or forest fire occurring within a particular area. These measures can include:

• Permanent restrictions - measures that are applied all year round within a particular area.
• Fire season restrictions - measures that are applied only during the normal fire season within a particular area.
• Temporary restrictions - measures that are only applied when the fire risk/danger index passes a pre-determined threshold within a particular area. Temporary restrictions are usually removed once the fire risk/danger index falls below a predetermined threshold.

Fire risk

The calculation of the probability of a wildfire occurring and its potential impact on a particular location at a particular time. Wildfire risk is calculated using the following equation:

Fire risk = probability of occurrence x potential impact.

Fire scar

a) The overall shape of the area burned by a wildfire or,

b) A healing or healed injury or wound to woody vegetation which has been caused or accentuated by fire.

Fire season

The period or periods within a year when wildfires are most likely to occur.

Fire severity

Fire severity can be defined in two ways:

• The degree to which a site has been altered or disrupted by fire.^[15]
• The capacity of a fire to cause damage.^[16]

Fire intensity and the amount of time a fire burns within a particular area, among other possible factors, will influence fire severity.

Fire severity Index

The Met Office Fire Severity Index is an assessment of fire severity for the current day and a forecast of fire severity for the coming five days.

Fire spread

The movement of a fire through available fuels arranged across the landscape.

Fire storm

Violent convection caused by a large continuous area of intense fire.

Fire suppression

The activities undertaken to extinguish a fire.

Fire suppression plan

A pre-determined scheme or programme of activities which is formulated in order to safely and effectively accomplish fire suppression objectives. A fire suppression plan will outline the selection of tactics, selection of resources, resource assignments and how performance and safety will be monitored and maintained at a particular incident. Fire suppression plans need to be dynamic to take into account any changes in conditions or circumstances.

Fire types

There are three different schemes for classifying fire type:

1. Classification of a fire or section of fire according to the fuel level within which it occurs. For example, aerial, crown, understory, surface and ground fires.

2. Classification of a section of fire according to its position along the fire perimeter. For example, head, tail and flank fires.

3. Classification of a fire or section of fire according to the visual characteristics it displays. For example, smouldering, creeping, backing, running, torching, spotting, crowning, fire whirl, convection driven fire etc.

Fire whirl

Spinning vortex column of ascending hot air and gases rising from a fire and carrying aloft smoke, debris, and flame.^[17]

Fire wind

The inflow of air close to a fire caused by the action of convection.^[18] Fire winds influence fire spread.

Flame angle

The angle of a flame measured in relation to the ground surface. Flame angle is expressed in degrees.

Flame depth

The distance from the rearmost to the foremost parts of the fire front, usually expressed in metres.

Flame height

The vertical extension of a flame. Measurement of flame height is calculated perpendicular from ground level to the tip of the flame. Flame height will be less than flame length if flames are tilted due to wind or slope.

Flame length

The total length of a flame measured from its base at ground level to the flame tip. Flame length will be greater than flame height if flames are titled due to wind or slope.

Flame risk

An assessment of risk to fire suppression personnel which is calculated using flame length.

Flaming combustion

The production of flames as part of the combustion process.

Flaming Front

The area of a moving fire where combustion is primarily flaming. The flaming front normally consists of the fire front and the flaming zone.

Flaming Zone

The flaming zone is located behind the fire front and is primarily characterised by flaming combustion. The flaming zone is where coarser fuels are consumed and where fire behaviour is typically less dynamic and more static. Depending on the fuels present, the fire can burn for a considerable length of time within this zone.

Flammability

Relative ease with which a given fuel will ignite and burn with a flame.

Flanks

The parts of a fire's perimeter that are roughly parallel to the main direction of fire spread.^[19] The flanks usually have less fire intensity than the head fire because they have a weaker alignment with wind or slope.

Flank attack

A method of fire suppression which involves attacking a wildfire along the flank or both flanks simultaneously.

Flare up

A short and sudden increase in fire activity.

Flash fuels

Fine fuels that have been dried and which will ignite very readily and rapidly.

Fog

Low lying parcels of air with high levels of moisture content. Fog is a cloud that has its base on the earth's surface.

Fogging System

Pressurized water system which produces a fine mist or micro droplets of water to enhance the heat absorbing and steam generating capability of water.

Forces of Alignment

A collective term for the forces that have a significant impact on wildfire behaviour. These forces can support or hinder fire development and can be used to predict likely fire behaviour, including fire spread and fire intensity. Wind, slope and aspect are considered to be key forces of alignment.

Fragmentation

The process of transforming large continuous areas of vegetation and fuel into smaller discontinuous areas. Fragmentation leads to a change in fire regimes through the alteration and discontinuity of fuels.

Fuel

Any material that can support combustion within a wildfire environment. Fuel is usually measured in tonnes per hectare.

Fuel Arrangement

The horizontal and vertical distribution of all combustible materials within a particular fuel type.^[20]

• Horizontal fuel arrangement - A description of the distribution of fuels on the horizontal plane. The horizontal arrangement of fuels will influence the relative ease with which fire can spread horizontally across an area of land.
• Vertical fuel arrangement - A description of the distribution of fuels on the vertical plane, from the ground up to the canopy levels of vegetation. The vertical arrangement of fuels will influence the relative ease with which fire can spread vertically through the fuel layers.

Fuel assessment

The estimation or calculation of total and available fuel that is present within a specific area.

Fuel complex

The type, quantity, condition, arrangement and continuity of fuel available to burn.

Fuel condition

Relative flammability of a fuel, as determined by fuel type and environmental conditions.^[21]

Fuel Continuity

The extent to which fuel arrangement will support fire spread.

Fuel consumption

The amount of a fuel that is removed by a fire, often expressed as a percentage of the fuel load.

Fuel hazard

A fuel complex defined by type, alignment, arrangement, volume, continuity, condition etc. that forms a special risk.

Fuel layers

The classification of fuels according to their height relative to the ground surface. There are five general fuel layers:

• Aerial fuels
• Elevated fuels
• Near surface fuels
• Surface fuels
• Ground fuels

Fuel Load

The amount of fuel present within a particular area. Fuel load is measured in weight per area measured (usually in kilograms per square metre). Fuel loading is expressed in relative terms as either "heavy fuel loading" or "light fuel loading".

Fuel management

The process of managing fuel or fuel arrangement. The aim of fuel management is usually to create a discontinuity in fuels to achieve fragmentation.

Fuel moisture content

Water content of a fuel expressed as a percentage of fuel weight when oven dried.

Fuel profile

Vertical cross-section of a fuel bed.

Fuel properties

The physical characteristics of a fuel; for example, volume, size, shape, compactness and arrangement.

Fuel separation

The distance between fuel layers or fuel particles.

Fuel type

A group of fuels that will respond to fires in a similar way.

Fuel type pattern

A mosaic of distinct fuel types within a particular area.

Fuel type classification

The division of wildland fuels into different fire hazard classes.

Geographic Information System (GIS)

A system designed to capture, store, manipulate, analyze, and present geographically referenced data.

Global Positioning System (GPS)

A global navigation system that provides very precise positioning information about the location of any point on or near the Earth's surface.

Glowing combustion

Low intensity combustion, when there is little or no flame and little or no fire spread. Glowing combustion will usually occur shortly before extinction, during the final stages of a fire.

Gradient

The angle or steepness of a slope.

Grassland

An area predominantly covered in one or more species of grass.

Ground crew(s)

Any crew(s) operating on the ground. Usually only required as a term of reference if an incident involves aerial operations.

Ground Fire

A fire burning below the surface fuel layer.

Ground fuel

Any fuel below the surface fuel layer, normally within the soil. Examples of ground fuels include: duff, tree roots, shrub roots, rotting wood, peat etc.

Hand line

A control line constructed using hand tools.

Head Fire

The leading part of an advancing wildfire at a particular point in time. The head fire will usually exhibit the highest level of fire activity of any part of the fire.

Heat Transfer

The process by which heat is imparted from one body or object to another. In wildfires and forest fires, heat energy is transmitted from burning to unburned fuels by:

• Convection - Transfer of heat by the movement of masses of hot air; the natural direction is upwards in the absence of any appreciable wind speed and/or slope. Convection can include spotting behaviour.
• Radiation - Transfer of heat in straight lines from warm surfaces to cooler surroundings.
• Conduction - Transfer of heat through solid matter.^[22]

Heathland

An area of open uncultivated land which is dominated by dwarf shrubs and which is usually characterised by poor acidic sandy soil. Heathland is similar in appearance to moorland, although heath is normally found on well-drained sandy soils at lower altitudes.

Helibase

The main location for parking, fuelling, repairing/maintaining, and loading of helicopters during a wildfire incident.

Holding area

Location established at an incident where resources can be placed while awaiting assignment.

Horizontal Fuel Arrangement

A description of the distribution of fuels on the horizontal plane. The horizontal arrangement of fuels will influence the relative ease with which fire can spread horizontally across an area of land.

Hot fire

When prevailing conditions cause fuels to burn and produce a high intensity fire or part of a fire.

Hot Spot

A small burning area which requires suppression action as part of the mop-up phase of suppression.

Humidity

A generic term used to describe the amount of water vapour in the air.

Hygrometer/ Psychrometer

An instrument used for measuring the relative humidity of the air.

Ignition

The initiation of combustion.

Ignition method

The means by which a fire is ignited.

Ignition patterns

A generic term for the three key techniques for igniting a managed burn:

• Line ignition - igniting a burn in strips along a control line and the adjacent fuel.
• Points of fire ignition - igniting a number of fires within an area of fuel. The aim of this technique is for the individual fires to burn into one another.
• Fingers of fire ignition ^[23] - a low intensity back burn which is achieved by igniting lines of fire at right angles to a control line and parallel to the wind.

Ignition point

The precise physical location within the area of origin where a wildfire was first ignited.

Ignition temperature

The minimum temperature at which ignition can take place and sustained combustion can occur.^[24]

Incendiary

A device that is designed to ignite a fire.

Incident

An occurrence or event that requires action to prevent or minimise loss of life, damage to property or damage to the environment.

Incident Commander

The nominated competent officer who has overall responsibility for safety, tactics and management of resources at a wildfire incident.^[25]

Incident Command System

A standardized emergency management system which is specifically designed to allow its users to adopt an integrated organisational structure equal to the complexity and demands of single or multiple wildfire incidents. An ICS provides a standard framework within which individuals and teams present at an incident can work together safely and effectively.

Incident support

A group or organisation responsible for providing personnel, equipment and/or welfare facilities and supplies in support of suppression operations.

Indirect attack

Any suppression methods implemented away from the fire edge.

Initial Attack

Suppression work completed by first responders arriving at a wildfire incident. The intention of any initial attack will always be to quickly gain control of a fire. If an initial attack is unsuccessful then a prolonged attack strategy might be required.

Initial response

The first suppression resources mobilised to an incident following the detection of a wildfire. These resources will be available to participate in initial attack operations.

Islands

Areas of unburned fuel within a fire perimeter.

Isobar

A line on a weather map which connects points of equal atmospheric pressure.

Isotherm

A line on a weather map which connects points of equal temperature.

Junction zone

An area where two separate fires move together. The junction zone is usually characterised by increased fire activity.

Junction Zone affect

This is the term used to describe the increased fire activity that occurs when two separate fires move together.

Katabatic Wind

Down slope winds. Katabatic winds occur when air at higher elevations is cooled (often at night) and is subsequently pulled down slope by the force of gravity.

Knapsack Sprayer

A portable hand operated water pump with a nozzle that can be carried on the back by personnel, used to apply water as a spray or a small. Often used to knock down the intensity of a fire or extinguish hot spots during the mop up phase.

Knock Down

To reduce the flame or heat of burning parts of a fire.

LACES

An essential safety protocol which should be implemented at wildfire incidents to address risks and hazards. The correct implementation of LACES helps to ensure that suppression personnel are appropriately supervised, informed and warned of risks and potential hazards and that they are aware of how and where to escape should a high risk situation occur.

LACES is an acronym for:

• L = Lookouts
• A = AwarenessError! Bookmark not defined. or Anchor Point
• C = Communication
• E = Escape route and plan
• S = Safe area

Ladder fuel

Fuels that provide vertical continuity which allow fire to move through the vertical fuel arrangement.

Land breeze

A local night time breeze which occurs when cooler, higher pressure air above the land surface moves offshore to replace warmer air rising above coastal waters.

Landscape

The physical appearance of the land comprising of the features of terrain, vegetation and the human impact caused by variations in land use.

Latitude

The angular distance north or south between a point on the earth's surface and the equator. Latitude is usually measured in degrees, minutes and seconds.

Litter

The top layer of debris fuels consisting of twigs, sticks and branches, it can also include recently fallen leaves and needles. The structure of the material within the litter layer has not been altered significantly by the process of decomposition.

Live fuels

Fuels with living tissue. The moisture content of live fuels is controlled largely by internal physiological mechanisms.

Lookout

A person that has a good understanding of wildfire behaviour and who acts as the safety officer for an individual team. He/she will observe the fire and the actions of the team and will be responsible for ensuring the safety of the whole team. Lookouts are a key element of the LACES safety protocol.

Managed burn

A planned and supervised burn carried out for the purpose of removing fuel either as part of a Fire SuppressionError! Bookmark not defined. Plan (an operational burn) or a land management exercise (a prescribed burn).

Meteorological winds

Meteorological winds are caused by differences in atmospheric pressure within upper level air masses which generate regional weather patterns.

Mineral Earth

A soil layer that does not contain organic material which could support combustion.

Mixed Woodland

A mixture of deciduous and coniferous tree species.

Moorland

An area of open uncultivated land which is dominated by dwarf shrubs and other low-lying vegetation. Moorland is similar in appearance to heathland; although moorland is found in wetter areas where mosses help retain water content.

Mop Up

The act of extinguishing a fire after it has been brought under control.^[26] Mop up involves carrying out all necessary actions to prevent re-ignition.

Multi-agency Incident

An incident involving more than one agency.

Multiple Ignition Points

More than one point of ignition. Multiple ignitions may be lit simultaneously or successively and could be indicative of spot fires or fires set deliberately by humans.

Natural fuels

Fuels created and developed through natural processes and which have not been directly generated or altered by land management practices.

Near surface fuels

Any fuels found at a height of 0.5-1.5 metres above the ground surface. Near surface fuels are found above surface fuels and have a vertical component to their structure.

Operational burn

A controlled supervised burn which is carried out by a burn team as part of a fire suppression plan. An operational burn can be classified as either offensive or defensive, depending upon its purpose:

• Offensive operational burn - ignited along a control line to burn into an advancing flame front.
• Defensive operational burn - ignited along a control line to strengthen/expand the control line, but will be extinguished prior to the arrival of an advancing wildfire.

Parallel Attack

A method of fire suppression involving the construction of a control line approximately parallel to and some distance away from the fire edge. The intervening strip of unburned fuel may or may not be burned out as the control line proceeds. This decision will be influenced by an assessment of whether the unburned fuel is considered to pose a threat to the control line.

Partner agency

Any organisations that work together to prevent, investigate and/or suppress wildfires. Partner agencies will work together on preparedness activities and plans and are likely to have formulated pre-agreed partnership agreements.

Patrol

The act of supervising a specified area in order to prevent, detect and/or suppress wildfire.

Peat

An organic fuel layer consisting of a light, spongy material formed in temperate humid environments through the accumulation and partial decomposition of vegetation debris. Peat is formed by decomposition in the absence of oxygen (anaerobic decomposition). Peat forms in areas that are seasonally or permanently inundated with water. Fires in peat burn by smouldering combustion and generate high levels of heat energy per unit area.

Pinching

Attacking a fire by working along the flanks either simultaneously or successively from a less active or anchor point and endeavouring to connect the two lines at the head.^[27]

Plantation

An area of trees created through artificial regeneration.

Points of fire ignition

A fire ignition pattern which involves igniting a number of fires within an area of fuel. The aim of this technique is for the individual fires to burn into one another.

Precipitation

All forms of water, whether liquid (e.g. rain) or solid (e.g. snow or hail), that fall from the atmosphere and reach the ground.

Preheating

Preliminary phase of combustion where fuels ahead of an advancing fire are heated and dried. During pre-heating, fuel temperatures are raised either by the advancing fire and/or by weather (i.e. solar radiation, aspect).

Preparedness plan

A pre-determined strategic scheme or programme of activities which is formulated in order to satisfactorily prepare an organisation or a geographic area to respond effectively to wildfire incidents.

Pre-treat

The application of water, foam or retardant along a control line.

Prescribed burn

A planned and supervised burn carried out under specified environmental conditions to remove fuel from a predetermined area of land and at the time, intensity and rate of spread required to meet land management objectives.

Prevailing wind

The predominant wind direction.

Public access

Land open to the public for recreational or educational use.

Rate of Spread

A measurement of the speed at which a fire moves across a landscape. Rate of spread is usually expressed in metres per hour.

Re-burn

Subsequent burning of an area that has already been burnt.

Rendezvous point

A pre-arranged location where resources arriving at a wildfire incident will report.

Reserve resources

Resources not assigned to a specific task, but available for deployment.

Resilience

The ability of an ecosystem or species to return to its original state after being affected by a wildfire.

Relative Humidity

The amount of water vapour present in the air expressed as a percentage of the amount of vapour needed for saturation to occur at the same temperature. Saturated air is referred to as 100% relative humidity.

Resources

Personnel, equipment, services and supplies which are either available or potentially available for assignment to a wildfire incident.

Response

Response encompasses the actions taken to deal with the immediate effects of a wildfire emergency. In many scenarios it is likely to be relatively short and to last for a matter of hours or days - rapid implementation of arrangements for collaboration, co-ordination and communication are, therefore, vital. Response encompasses the effort to deal not only with the direct effects of the emergency itself but also the indirect effects.

Responsibility

The duty or obligation to satisfactorily perform or complete an assignment.

Restricted area

An area in which specified activities or entry are temporarily or permanently restricted in order to mitigate risk to human health or safety by potential or on-going wildfires. A restricted area may also be temporarily or permanently established in order to reduce the risk of a wildfire igniting within a specified location.

Ring burn

A fire started by igniting the full perimeter of the intended burn area so that the ensuing fire fronts converge toward the centre of the burn.^[28]

Risk assessment

A process involving the identification of risk, an assessment of probability and an assessment of potential impact. The process will establish information regarding acceptable levels of risk and actual levels of risk posed to an individual, group, society or the environment.

Risk management

A process involving the systematic application of policies, procedures and practices to identify, analyse, evaluate, manage, control, communicate and monitor risks.^[29]

Role rotation

The act or process of periodically changing the assignments provided to individuals working at a wildfire incident to ensure adequate rest breaks and appropriate variety in the physical and mental intensity of tasks completed by all team members.

Running Fire

A fire that is rapidly spreading with a well-defined head.

Safe area

An identified area of safety where people will find refuge. The identification of a safe area is a key element of the LACES safety protocol.

Safe systems of work

A formal procedure which results from systematic examination of a task in order to identify potential hazards and risks. The resulting document produced will describe the safest way(s) of completing a task to ensure hazards are eliminated or that risks are controlled as far as possible.

Safety

When exposure to hazards has been controlled to an acceptable level.

Safety Officer

An officer that is appointed to manage risk.

Scratch Line

A preliminary control line that has been hastily constructed as an emergency measure to prevent fire spread.

Scrubland

Area of mixed vegetation predominantly consisting of shrubs, bushes and grasses. Scrubland may be found on the fringes of other fuel types, but it may also be found in isolated pockets within other fuel types.

Sea breeze

A daytime breeze in which cooler, higher pressure air from over coastal waters moves on shore to replace heated air rising off the warmer land mass.^[30]

Sector

A specific area of an incident which is under the control of a Sector Commander.

Shrub

A woody perennial plant characterised by its low stature (less than 3 m high) and habit of branching from the base. Shrubs normally contain a high quantity of fine fuels.

Situational Awareness

The perception of the surrounding environment within the context of both time and space. It includes the comprehension of meaning of observed phenomena and patterns and the provision of information relevant to a team or individual's situation. It also includes the projection and prediction of what will happen within the surrounding environment in the future.

Site of Special Scientific Interest

A statutory designation in Great Britain that offers protection to habitats, species and geographical features.

Slash

Debris left lying on the ground after logging, pruning or thinning operations within woodland. Slash may consist of both course and fine fuels and sometimes forms a significant surface fuel (It is often referred to as Brash or Hagg in Scotland).

Sleeper fire

A fire that remains dormant for a period of time.

Slope

An incline of the ground.

Slope affect

Variations in fire behaviour induced by slope. Slope can both support and hinder fire spread and development and the angle of the slope will have an important influence on the degree of effect.

The following descriptions explain the general slope effect that would be expected from a fire spreading upslope and a fire spreading down slope:

• Fires spreading upslope -The flames of a fire spreading upslope will be angled towards the unburned fuel above it which will pre-heat the fuel in front of the advancing fire. This pre-heating increases combustibility and rate of spread for fires travelling upslope.
• Fires spreading down slope - The flames of fires burning down slope will be angled away from the fuel and will, therefore, lead to less preheating of the fuel in front of the fire. Consequently, the effect of slope on a fire burning down slope is a reduction in combustibility and rate of spread.

Slope winds

Highly localised convective winds that occur due to heating and cooling of a slope.

• Katabatic winds - Down slope winds. Katabatic winds occur when air at higher elevations is cooled (often at night) and is subsequently pulled down slope by the force of gravity.
• Anabatic winds - Upslope winds. Anabatic winds occur when daytime solar radiation heats air at lower elevations causing it to flow upslope.

Smoke

The atmospheric suspension of small particles of solids and liquids produced by combustion

Smouldering combustion

Low intensity combustion, when there is no flame and little or no fire spread.

Smouldering fire

A fire burning without flame and barely spreading.

Solar radiation

Energy emitted by the sun which indirectly heats the earth's surface. Solar radiation has a significant influence on weather.

Spark

An ignited particle thrown from burning material.

Special Area of Conservation

Area designated under the EU Habitats and Species Directive.

Special Protection Area

Area designated under the EU Birds Directive.

Spot Fire

A fire outside the main fire perimeter which is caused by flying embers transported by the wind or convection column.

Spotting

Fire behaviour characterised by sparks and embers that are transported through the air by the wind or convection column. Spotting can be classified as short range or long range.

Stand

Trees of one type or species grouped together within woodland.

Standard Operating Procedures (SOPs)

SOPs are written instructions that detail the necessary steps that must be taken when completing a particular process or activity. The purpose of a SOP is to ensure that a particular process or activity is always carried out safely, effectively and in the same manner.

Standing fuel

Part of vegetation, living or dead, that is supported by a stem, branch or trunk.

Statutory responsibility

A legal obligation to satisfactorily perform or complete a particular task related to wildfire suppression or prevention.

Supplies

Minor items of equipment and all expendable items assigned to an incident. ^[31]

Supply area

The location, at which the primary logistics functions and supplies required for a wildfire incident are temporarily stored, coordinated and administered.

Suppression

All work involved in controlling and extinguishing a wildfire.

Surface Fire

A fire that burns within the surface fuel layer.

Surface Fuel

Any fuels found at a height of 0-0.5 metres above the ground surface.

Swipe

Used to cut small shrubs such as heather down to ground level. Depending on local conditions the resulting break in the vegetation can either act as a barrier to fire spread, or reduce fire behaviour significantly.

Tail fire

The rear most part of a wildfire/forest fire, it is normally out of alignment with wind and slope, and consequently will usually demonstrate less fire activity than the head fire because it usually has less support from wind or slope. Sometimes referred to as the heel part of the fire.

Tactics

The deployment of resources at a wildfire incident to achieve the aims of a strategic plan.

Tactical lookout

A person with an advanced understanding of wildfire behaviour who acts as a safety officer at a wildfire incident. He/she will observe the fire and the action of teams involved in fire suppression. He/she will maintain close communication with suppression teams and supervisors and will be responsible for ensuring the safety of all individuals present at the incident. Lookouts are a key element of the LACES safety protocol.

Test burn

A small burn which is ignited to observe and evaluate fire behaviour prior to igniting a larger operational or managed burn.

Thermograph

A thermometer that automatically and continuously records air temperature on a chart.

Thermometer

An instrument used to measure air temperature.

Time lag

The time it takes for fuel of various sizes to gain or loose moisture due to changes to the environment.

Topographic wind

When the direction and/or speed of a meteorological wind is altered by the shape of the landscape. Importantly, topographical winds are a general wind adaptation and they occur on a larger scale than more localised slope winds.

Topography

The description and study of the shape and features of the land surface.

Tree

A tree is a perennial woody plant with a single main stem or trunk which supports branches above the ground. Trees usually have a distinctive crown.

Trigger Point

A pre-designated point in time or place whereby a predicted change in fire behaviour will influence tactical decision-making. For instance, if a wildfire reaches a particular trigger point on the landscape, the Incident Commander may decide it is necessary to adopt alternative tactics in order to maintain safety and effectiveness.

Torching

A fire that burns from the ground through the surface and aerial fuels and into the crown of a single tree or small parcel of trees.

Understory

Vegetation found beneath the canopy, but which is normally found growing or lying on the ground.

Uniform fuels

Identical or consistent fuels distributed continuously across an area or landscape. It is usually easier to predict fire behaviour for fires burning in uniform fuels than it is for fire in mixed vegetation types.

Vegetation

A term used to describe all forms of plant life.

Vertical Fuel Arrangement

A description of the distribution of fuels on the vertical plane, from the ground up to the canopy levels of vegetation. The vertical arrangement of fuels will influence the relative ease with which fire can spread vertically through the fuel layers.

Weather

The state of the atmosphere at a given time and place with respect to atmospheric stability, temperature, relative humidity, wind speed, cloud cover and precipitation.

Weather Station

A collection of sensors and monitors which gathers, records and reports meteorological data. Weather stations may be permanent structures or hand-held/semi-portable/portable units.

Wet line

A line of water, or water mixed with fire fighting chemicals, which is sprayed along the ground to serve as a temporary control line from which to ignite an operational burn or to stop a low-intensity fire.

Wildfire

Any uncontrolled vegetation fire which requires a decision or action regarding suppression. Wildfires are commonly classified according to size and/or impact upon suppression resources.

Wildfire Prediction System

A method used to analyse a fires potential alignment with wind, slope and aspect as it moves across the landscape and predict its likely fire behaviour within the available fuel.

Wildland

An area in which development is essentially non-existent, except for the presence of basic infrastructure such as roads, railroads and power lines. Any buildings and structures will be widely scattered.

Wildland Urban Interface

The zone of transition between wildland and human settlements and/or development.

Wind

The horizontal movement of air within the atmosphere. Wind has a strong influence on fire behaviour and is one of the key forces of alignment.

Wind direction

The direction from which the wind is blowing. A change in average wind direction is termed a "wind shift".

Wind shift

A change in average wind direction.

Wind speed

The rate at which air moves horizontally past a particular location at a particular point in time.

Window of opportunity

A period of time or location on the landscape when/where it will be particularly advantageous to adopt particular suppression tactics or actions.

Windrow

Woody debris that has been piled into a long continuous row.

Woodland

A generic term for any area of land which is predominantly characterised by trees, whether in large tracts or smaller units.33

Woodland can be categorized according to the types of species it contains, for instance:

• Coniferous woodland - containing predominantly coniferous tree species.
• Deciduous woodland - containing predominantly deciduous tree species.
• Mixed woodland - Woodland containing a mixture of coniferous and deciduous tree species.

Woodland can also be categorized according to the degree to which humans manage the area, which has an influence on the type of fire behaviour that may be observed:

• Planted woodland - An area of managed woodland (often artificially established) where trees are grown for sale as timber and/or for the commercial production of other forest products. Planted woodland is often characterised by a single species and continuity in both the horizontal and vertical fuel arrangements.

Natural woodland - Trees that have germinated and grown in their natural state without the influence of human actions. Natural woodland is likely to contain multiple species of trees which leads to less continuity of fuels than is found in planted woodland.