Publication - Advice and guidance

Fire and Rescue Service Wildfire Operational Guidance

Published: 21 Oct 2013
Part of:
Law and order
ISBN:
9781782564980

This guidance has been produced to give fire and rescue service personnel an additional understanding and awareness of the phenomenon of wildfire. It examines the hazards, risks and controls relating to Fire and Rescue Service personnel, the personnel of other agencies and members of the public at Incidents of wildfire. It also provides a point of reference for those who may be called upon to plan for wildfire events and for those incident commanders and personnel responding to such incidents.

362 page PDF

13.9 MB

362 page PDF

13.9 MB

Contents
Fire and Rescue Service Wildfire Operational Guidance
8B4 The Understanding and Use of Topographical Maps

362 page PDF

13.9 MB

8B4 The Understanding and Use of Topographical Maps

Introduction

8B4.01 Some of the wildfire issues that UK FRSs are required to address are complex; others such as acquiring an appropriate standard of map reading and navigational expertise are simpler. One thing is certain however, without the basic skills to operate effectively within a spatial environment, operational capabilities at a wildfire incident will be limited.

8B4.02 Maps are not only a navigation tool, they can also be used to improve the incident command system, address safety issues and assist in formulating a more complete understanding of the operational environment. Unless FRS personnel are trained in the basic skills necessary for them to operate at incidents that take place within the wider rural environment, there will be an inherent weakness in FRS response capability. In addition, Section B7 shows how maps can also be used to assist the Incident Commander to effectively sectorise a wildfire incident.

The Use of Maps at Wildfire Incidents

8B4.03 Wildfires usually occur in more rural or even remote rural areas. As a result the use of maps during these incidents is both necessary and unavoidable. All FRSs should provide personnel with training that is appropriate to the identified risk, thus ensuring that these invaluable aids are used to their full potential.

Maps can be used as:

  • A navigation tool
  • A safety tool
  • A planning tool

Maps as a Navigation Tool

8B4.04 An Ordnance Survey (OS) map is a useful navigation tool that can be used to identify features on the landscape, such as roads, tracks, buildings and structures, different vegetation types and the lay of the land. All of these can be used as points of reference to identify what is actually seen on the landscape and the features' position on it.

8B4.05 Importantly, maps can be used to measure or estimate distance and travel times. When used in conjunction with a compass they provide an accurate method of navigation.

8B4.06 An understanding of how to use maps as a navigation tool, provides personnel with the expertise to safely move across the landscape, and allows officers to identify any hazards that may pose a risk to the personnel they have responsibility for. At a wildfire, or indeed at other types of spatial incidents, it is essential that individuals have skills that allow them to quickly travel to the scene of operations. FRSs should have sufficient numbers of personnel that have appropriate navigational skills.

Maps as a Safety Tool

8B4.07 A map is an accurate representation of an area of ground, providing risk critical information that can be used to improve safety at a wildfire incident. Maps show the shape of the terrain and give important information on locations where fire behaviour may alter. This might include such things as the steepness of slopes, changes in vegetation types, or locations where fire alignment may change. Maps therefore play a crucial part in identifying the risks that may be encountered during a wildfire event.

8B4.08 The information contained on a map can assist in maintaining a high level of understanding of the operational environment and help establish a raised level of situational awareness. The ability to read maps plays an important role within the risk assessment and the decision making processes. This guidance also encourages the use of the LACES safety protocol (see Section B7) at wildfire incidents; having an understanding of maps is an integral part of this safety system. Maps provide essential information for lookouts, assist in the communication process and can be used to help plan escape routes and safety zones.

Maps as a Planning Tool

8B4.09 At a wildfire incident maps must be utilised as a planning tool as they are an indispensable aid to effective incident command. The effective use of maps within the planning processes will assist in the formulation of an effective suppression plan. Personnel on the incident ground can also use their understanding of maps to relay important intelligence to incident commanders.

8B4.10 Maps can be used to assist in deciding what tactics should be used at a wildfire incident. Information provided on a map includes intelligence on the following:

  • Changes to fuel
  • Critical points
  • Steepness of slopes
  • Aspect
  • Windows of opportunity
  • Fuel breaks
  • Areas of habitation
  • Natural or man-made control lines
  • Other obstacles to fire travel

8B4.11 These can be used to identify changes to fire behaviour as it moves over the landscape, and by applying the Wildfire Prediction System (see Section B6) to a map, it is also possible to construct a fire footprint that will identify likely fire travel.

Map Reading and Navigational Skills

8B4.12 FRSs managers must consider the risks posed to operational personnel by local geography, and ensure that suitable training is provided. It would, however, be impractical to suggest that every firefighter should be trained to an accredited standard of navigation.

8B4.13 Nevertheless, if FRS personnel are expected to operate at incidents that take place in rural or remote areas, they should be provided with appropriate expertise relevant to their role. They should also be supervised by well-trained officers who have the expertise to effectively manage resources during a spatial incident.

Essential Understanding of Maps and Navigation

8B4.14 Firefighters who may have to operate at spatial incidents should understand:

  • Map scales, contour lines, symbols, and grid squares
  • How to give a four- and six-figure grid reference
  • How to orientate a map to the landscape
  • How to recognise features of terrain
  • Cardinal directions
  • How to estimate distance
  • How to follow paths and tracks on the landscape that are identified on a map
  • How to understand the use of the Global Positioning System
  • Mobile data

Advanced Navigation

8B4.15 If it is necessary to leave recognised paths and tracks it is essential that personnel possess, or are supervised by individuals that have more advanced navigational skills. These should have the expertise to:

  • Take a compass bearing from a map
  • Use a compass to follow bearings accurately over short distances of open ground
  • Accurately estimate distances and travel time
  • Accurately measure distance using double pacing
  • Plan and follow a safe route over short distances
  • Understand how to use features of terrain as reference points
  • Select an appropriate speed of travel
  • Lead groups of people that operate on the ground

Specialist Navigation

8B4.16 Officers with specialist knowledge of navigation can provide additional support at incidents that pose higher levels of risk.

These should have the expertise to:

  • Use landform features as a method of navigation
  • Use contour information to understand the positioning of landscape features
  • Use a compass to navigate across long distances of open ground
  • Use compass bearings to navigate across intricate terrain
  • Use a compass to move around obstacles that force a deviation from a planned route
  • Navigate in darkness
  • Use back bearings to confirm position
  • Use contour information to confirm personal position and as a method of navigation

Ordnance Survey (OS)

8B4.17 Ordnance Survey (OS) is a non-ministerial government department and an Executive Agency responsible to the Secretary of State for Communities and Local Government. OS has a number of agreements with the public sector including the One Scotland Mapping Agreement, and the Public Sector Mapping Agreement for England and Wales. There are various types of maps including, digital and paper based, which can be utilised by FRSs under the public sector agreements. This guidance provides information on the use of OS paper maps which provide accurate geographical information.

Topographical Maps

8B4.18 A topographical map is a simplified bird's-eye view of a piece of ground, drawn to scale and showing physical and man-made features present on the ground. Information is presented in a unique format, through the use of symbols depicting various features, which are explained in the map legend, colours and shading, and contour lines which join points of equal height defining the shape of the terrain. OS maps also give direction, as all maps are orientated towards the north and have a positioning referencing system which is part of a geographical grid system.

The OS National Grid System

8B4.19 It is important that all FRS personnel are able to understand a topographical map and use the information available on it. At a wildfire incident, they must also have the ability to pinpoint their location using a map, and understand the positioning of features of terrain both on a map and on the landscape. A useful way of communicating an accurate position is by using grid referencing.

8B4.20 The British National Grid is a geographical grid referencing system that is used to divide the country into about 50 100km x 100km squares. These are either referenced numerically or alphanumerically. Each of these 100km grid squares is uniquely numbered from the bottom left corner of the UK and also has a unique 2 alpha character code. The alpha characters are not always marked on Ordnance Survey Landranger or Explorer maps so can be difficult to reference. The numeric system is always referenced on all OS maps and is therefore more reliable. Electronic systems, such as those used in Mobile Data Terminals (MDTs), use this system and it is referred to as a 12-figure grid reference.

It is normal to reference printed maps with the alphanumeric system if known and the most common form of this is the six figure grid reference. Various ways of expressing alphanumeric references are described below.

8B4.21 Positioning within large areas is focused by dividing each of the 100km grid squares into 10km-wide grids. These are identified by adding a two-number grid reference to the alpha code, for example TL-63. This identifies a 10km x 10km square grid (100km2) found 60km east and 30km north of the south-west corner of the TL grid square. (All grid squares of whatever size are identified by using the vertical and horizontal lines that intersect at the south-west corner of the square in question). As greater accuracy is required, each square is further sub-divided by 10 from 10km to 1km to 0.1km and so on.

Fig. B4.1 The OS National Grid

Fig. B4.1 The OS National Grid

Fig. B4.2 Grid square

Fig. B4.2 Grid square

OS Map Grid Squares

8B4.22 OS maps are covered in a series of faint blue lines that make up a square kilometre (1km²) grid. The lines have a number accompanying them that can be used to pinpoint positions on the map.

 Photo B4.1 Showing grid squares and grid numbers

Photo B4.1 Showing grid squares and grid numbers

The grid numbers can be located along the edges of an OS map on the margin and also at 10km intervals on the map itself.

Photo B4.2 Grid numbers running across the map

Photo B4.2 Grid numbers running across the map

Grid Referencing

8B4.23 The horizontal lines going across the face of the map, left to right or west to east are called Northings, i.e. line 45. All the lines going from the bottom to the top of the map, or from the south to the north are called Eastings, i.e. line 19. When giving a grid reference the Eastings number must always be given first followed by the Northings number.

8B4.24 During operations at a wildfire four- and six-figure grid references will be commonly used to identify positions on a map or on the landscape. Operationally, it is important that all FRS personnel are able to understand how to use grid referencing.

Fig. B4.3

Fig. B4.3

Four-figure Map References

8B4.25 Using the numbers that identify each Eastings and Northings line, a four-figure reference number can be used to identify each individual km2 contained within the blue grid lines shown on an OS map. The reference is always given from the bottom left corner of the grid square.

For example, the number 2 in the diagram below is 19 across and 45 up and therefore the four-figure grid reference is 1945.

Fig. B4.4

Fig. B4.4

The numbered squares on the diagram would have the following four-figure grid references:

1 = 1845
2 = 1945
3 = 1844
4 = 1944

Six-figure Grid Reference

8B4.26 A six-figure grid reference simply allows more accuracy by sub-dividing each square into tenths; this is physically not shown on a map but can easily be estimated. Using the example below, the grey box is positioned within the square 1844. More accurately it is 7-tenths across and 8-tenths up within grid square 1844. Therefore it has a six-figure grid reference of 187448. It is important to note that a six-figure grid reference is not unique as it will be represented within each of the 100km grids. If there is a need to make it unique then it must be prefixed with the alpha characters previously described. Therefore the grid reference would become TL 185443.

The red shape is located at six-figure grid reference 185443 or TL 185443.

Fig. B4.5

Fig. B4.5

Ordnance Survey Explorer and Landranger Maps

8B4.27 Both the Explorer and the Landranger paper maps provide extensive geographical information and present this in a similar, but not identical, format. It is important to understand that OS maps do not cover a 100km x 100km national grid square but are considerably smaller. They may cover areas that are within more than one national grid square and these are identified on the map.

The OS Explorer Map

8B4.28 Great Britain is covered by 403 separate explorer maps which use a 1:25000 scale, this equates to 4cm to a km or roughly 2½in to a mile. They show considerable detail which is useful in connection with navigation but can make the interpretation of relief, particularly contour detail difficult to read. Explorer maps do not cover as much area as those covered by the Landranger maps.

Photo B4.3

Photo B4.3

The OS Landranger Map

8B4.29 There are 204 Landranger maps each covering an area of 40km by 40km, they use a 1:50000 scale which equates to 2cm to a km, or roughly 1¼in to a mile. These are less detailed than the OS 1:25000 maps and do not show walls or fences which are useful indicators when navigating. Due to their increased scale they can be easier to read, particularly in relation to relief.

Photo B4.4

Photo B4.4

Information on a Map

8B4.30 There is a huge amount of useful information on a map, but a lot of it is in a form that needs to be interpreted. Therefore, all OS maps have some explanatory information which is available in the form of a legend. This provides details on how features are represented and on the different symbols used.

See Appendix 2 showing Legend of 1:50000

See Appendix 3 showing Legend of 1:25000

Topographical Information

8B4.31 Maps give an accurate interpretation of the relief found on a landscape. This information is presented in a unique format that proves to be exceedingly useful during wildfire incidents. There are various mapping systems available for use, but topographical maps prove to be the most useful.

8B4.32 Nevertheless, the gathering of relevant intelligence is essential if fire service managers are to formulate effective plans, therefore all relevant means should be used. Visual aids such as aerial photography is now easily obtained and, wherever possible, should be utilised at incidents alongside topographical maps.

Photo B4.5

Photo B4.5

Photo B4.6

Photo B4.6

8B4.33 The illustrations above show the contrast between topographical maps and aerial photography, each show a representation of same area, but provide different information. Topographical maps are in a format that displays data that is strongly related to relief, accurately showing the shape of the landscape and the position of features on it. Distances can be easily measured using the relevant 1:25000 or 1:50000 scales. Aerial photography presents a visual representation that can give more detailed information on fuel and in particular its horizontal arrangement. It also identifies features that may not be included on a topographical map such as clearings, informal tracks or paths, or changes in land use across the landscape. When referring to either topographical maps of aerial photography, it is crucial to appreciate that older material may contain inaccurate information. An example of this is the changes that occur to woodland, where trees may have been planted or harvested.

Understanding Contours

8B4.34 Contour lines are used on topographical maps to define the shape and height of the surface of the ground. The lines are shown as faint orange or brown lines that join together points of equal height. These lines are separated by what are termed to be vertical intervals, or measured height differences between each line. On a 1:50000 scale map this is always 10-metre intervals.

8B4.35 On a 1:25000 scale map the contours are normally 10 metres, but the interval can be 5, 10 or 20 metres depending upon the prevailing terrain.

Photo B4.7 Showing contours on an Explorer map

Photo B4.7 Showing contours on an Explorer map

8B4.36 In mountainous areas this interval may be greater; this is to prevent the insertion of too many contour lines into a small space.

Photo B4.8 Showing the contour interval

Photo B4.8 Showing the contour interval

Upslope and Downslope

8B4.37 How contour lines display upslope and downslope is important, as it is this information that allows an interpretation of the shape of the ground. Contour lines show a number indicating height in metres, which is always displayed as an ascending value. If the numbers increase in value this denotes an uphill slope and as the value decreases they indicate a downhill slope. Usefully, the top of the number is always printed so that it points upslope, while the bottom of the number points downslope. To make maps easier to read, each fifth contour line is drawn thicker, and is known as an Index Contour Lines.

Photo B4.9 The direction of a slope is indicated by the contour interval numbers

Photo B4.9 The direction of a slope is indicated by the contour interval numbers

8B4.38 Where contour lines are placed close together they represent a steep slope, where they are further apart the ground is more level. This gives a very accurate representation of the shape of the landscape.

Photo B4.10 Contour line showing detailed terrain information

Photo B4.10 Contour line showing detailed terrain information

Interpreting Relief

8B4.39 Having an understanding of the shape of the ground is extremely useful during wildfire incidents. This information is important when formulating a plan or carrying out an operational task on the fire ground. Differentiating between upslope and downslope is particularly useful and by making reference to the shape of contour lines it is possible to understand topographical features. This can help determine the influence the terrain may have on fire development. The patterns formed by contour lines give a visual representation of the shape of the landscape. By making reference to these contour patterns, hills, valleys, re-entrants, ridges, spurs, and other ground features can be recognised.

Fig. B4.6 The contours indicate the profile of the landscape

Fig. B4.6 The contours indicate the profile of the landscape

8B4.40 The relationship between higher and lower contours and the distance between them can give you valuable clues about the shape of the surface on the ground.

  • Decreasing ring contours denote a summit or basin, but inside a circle is normally higher ground
  • Flat areas have very few contour lines
  • Contours placed very close together indicate a very steep slope
  • V or U contour shapes pointing uphill indicate a re-entrant
  • V or U contour shapes pointing downhill indicate a spur
  • Contours descending on either side of a line show a ridge
  • Contours grouped together on either side of lower ground normally indicate a valley

8B4.41 Contour lines show patterns that indicate the horizontal and vertical shape of the surface of the ground, at a wildfire this can help identify parts of the landscape where:

  • the rate of fire travel may increase or decrease
  • there will be a change to fire intensity
  • a fire is in or out of alignment with slope
  • parts of the landscape are in or out of aspect
  • wind direction may change
  • wind strength may increase
  • parts of the landscape that will have a critical effect on fire behaviour
  • points on the landscape will trigger changes to fire behaviour which may result in a re-assessment of suppression tactics
  • routes may be identified to get to and from the scene of operations
  • safety zones can be located
  • escape routes can be found

Calculating Distance on a Map

8B4.42 Distances on a map can be calculated using a number of different methods; these provide a varying degree of accuracy.

Measuring Distance Using Grid Squares

8B4.43 Grid squares on a map offer a quick method to estimate distance. Each one of the grid squares represents a distance of 1km along its edge, or 1.4km when measured diagonally from corner to corner. By counting the number of grid squares between two points, and adding 100 metres for every tenth of a grid square, a rough calculation of distance can quickly be made.

Using Map Scales to Measure Distance

8B4.44 The scale used on a map is a ratio between map unit and ground unit, any measurement taken from a map can therefore be converted into actual distance. A ruler can be used to accurately measure the distance between two points, this measurement can then be converted by using a maps linear scale. On a 1:50000 OS map this equates to 1cm to 50000cm, or 1cm to 500 metres. On a 1:25000 OS map it is 1cm to 25000cm or 1cm to 250 metres. All OS maps have a linear scale which is located along the bottom margin.

8B4.45 In reality, it is unlikely that personnel will be able to proceed across terrain using a direct route. It should be acknowledged that there are methods for measuring indirect routes which may give a more accurate assessment of the distances to be travelled. For example, indirect distances can be measured using measuring wheels, digital mapping software or even a length of string.

Map Ratios

Ratio = 1:25000

25000cm on the ground

1cm

250 metres on the ground

0.25km on the ground

Ratio = 1:50000

50000cm on the ground

1cm

500 metres on the ground

0.50km on the ground

Measuring Distance on the Ground

8B4.46 Being able to calculate distance on the ground is very important, and there are two main ways ground distance can be measured; these are known as pacing or timing.

Single Pacing Method

8B4.47 Pacing is a practical method of estimating distance on the ground, it is based around having an understanding of how many paces an individual takes to walk a distance of 100 metres. To find out a pacing average an individual should walk 400 metres over a route that has been set on level ground, a count should be made of the total number of steps taken to complete the course. This total should be divided by 4, the resulting number is the average number of paces required to cover 100 metres. This average pacing can be used by an individual to measure distance covered on the ground. For example, if it is known that a person's average pacing is 126, every 126 paces taken will equate to 100 metres. Distance can then be estimated by counting multiples of 100-metre measurements.

Double Pacing Method

8B4.48 Double pacing is the preferred method for estimating distance on the ground and has been adopted by a number of UK FRSs as it reduces the amount of counting required. The process used to establish an average double pacing is similar to that used for establishing single pacing averages, the only difference being that only every other pace is counted. This is achieved by starting on the right foot and counting the number of times the left foot is placed on the ground. The double pacing average can then be used to measure ground distances in the same way as the single pacing method.

Measuring Distance by Estimating Travel Time

8B4.49 Distance can also be measured by calculating the time it takes to travel between two points. By estimating an average speed a person can be expected to travel across the existing terrain, and by making adjustments for ascents and descents, a travel time can be estimated. Average speed is affected by surface conditions, type of terrain, time of day, gradients, equipment being carried and the type of PPE worn.

See Plate B4.1 Chart with Travel Times

See Plate B4.2 Chart with approximate speeds for given terrain

Navigation

8B4.50 An understanding of maps, and the ability to relate the information on the map to what can actually be seen on the ground, can provide some capacity to navigate across the landscape. Unless personnel have advanced or specialist map reading skills, navigation should be restricted to recognised paths and tracks that are shown on a map.

Cardinal Directions

8B4.51 The cardinal directions are all based on north being the base of 0 or 360 degrees. There are eight cardinal directions which are shown in dark blue, each one of these can be found by measuring degrees clockwise from north.

Fig. B4.7 The dark blue arrows show the cardinal directions

Fig. B4.7 The dark blue arrows show the cardinal directions

North
at 0 or 360 degrees
South
at 180 degrees
Northeast
at 45 degrees
Southwest
at 225 degrees
East
at 90 degrees
West
at 270 degrees
Southeast
at 135 degrees
Northwest
at 315 degrees

Fig. B4.8 Cardinal directions

Understanding the Use of a Compass

8B4.52 This guidance highlights the need for map reading and navigation skills, it is not intended to provide detailed information on either. The following section contains a basic description of a lightweight or Silva compass and its use.

8B4.53 A compass is an instrument that can be used to help find your way across the landscape. Before using a compass you need to have an understanding of its basic features.

The Main Features of a Compass

Fig. B4.9 The main features of a compass

Fig. B4.9 The main features of a compass

1. Base plate

2. Compass housing - also known as the compass wheel, it has a mark every 2 degrees.

3. Magnetic needle - the red end will point to magnetic north.

4. Orienting lines - fixed within the compass housing and designed to be aligned to the Eastings on a map.

5. Orienting arrow - fixed and aligned to north within the compass housing.

6. Index line - extension of the direction of travel arrow where the compass user reads off a bearing.

7. Direction of travel arrow - the arrow at the end of the base plate.

8. Map scales - used to measure distances on 1:50000 and 1:25000 scale maps.

8B4.54 The main working part of the compass is the magnetic needle which rotates on a central pivot. The red end of the needle always points to the Earth's magnetic north. By rotating the compass housing to line up the red north end of the needle with the red arrow on the compass baseplate, a bearing can be taken from the index line. To get an accurate reading you then have to adjust the bearing to take account of the difference between grid north and magnetic north. The degree of magnetic variation can be found on all OS maps.

8B4.55 When taking a magnetic bearing the compass needle can be influenced by nearby metallic objects which may affect the accuracy of the reading.

The Main Uses of a Compass

8B4.56 A compass can be used in a number of ways including:

  • Taking a bearing from a map and following this to reach a specific position
  • Orientating a map so that it matches what is seen on the ground
  • Using a bearing to identify features found on the ground
  • Identifying your own position on the landscape

8B4.57 The first two uses are covered in detail within this guidance, whereas the last two uses are more practically-based skills which should ideally be taught in an outdoor environment and are therefore not addressed within this chapter.

Setting Direction of Travel from a Map

8B4.58 There are three simple stages to transferring the direction you want to travel shown on a map, to the direction you need to travel on the ground using a compass.

Stage One

8B4.59 The compass should be laid flat on the map with one of the long edges joining the two points of travel ensuring that the compass is facing in the correct direction.

Photo B4.11 Stage 1 – The direction of travel arrow should always point towards the intended destination

Photo B4.11 Stage 1 - The direction of travel arrow should always point towards the intended destination

Stage Two

Photo B4.12 Stage 2

Photo B4.12 Stage 2

8B4.60 Keeping the base of the compass in position on the map, the compass housing is rotated until the compass orienting arrow points north/upwards and the orienting lines on the compass housing are parallel with the grid (Eastings) lines on the map.

Stage Three

8B4.61 The compass can then be taken from the map and any magnetic variation should be added by turning the wheel in an anti-clockwise direction. The compass is now set in a horizontal position; the compass should be turned until the red end of the magnetic needle is positioned inside the orienting arrow and the direction of travel arrow points towards the destination.

Photo B4.13 Stage 3

Photo B4.13 Stage 3

Aligning a Map

8B4.62 If you know your position on the landscape and can locate this on a map, you can use known features as reference points. Roads, rivers, power lines, stone walls, fences and other features can be used to align a map. By rotating the map so that it matches what is seen on the ground will clarify the relationship between the two.

Orientating a Map

8B4.63 The grid lines running from the bottom to the top of a map (Eastings) are drawn to the north. By using these and a compass the map can be accurately orientated to align with magnetic north.

There are two stages to this process:

Stage One

8B4.64 Set the north mark on the compass housing so that it aligns with the direction of travel arrow. Then place the compass on the map so that the direction of travel line is running along Eastings, or towards the top of the map. The edges of the compass base plate will run parallel with the grid lines on either side of the compass.

Photo B4.14 Stage 1

Photo B4.14 Stage 1

Stage Two

8B4.65 Holding the map and compass firmly in place, rotate the map until the north end of the compass needle points north along the grid line, sitting within the orienting arrow.

Photo B4.15 Stage 2

Photo B4.15 Stage 2

8B4.66 The map and the compass are now orientated against magnetic north and the map will align with what is seen on the ground.

Electronic Systems

8B4.67 Mobile Data Terminals (MDTs) use a 12-figure grid reference and it is important to understand the relationship between an alphanumeric and a 12-figure grid reference.

Photo B4.16

Photo B4.16

An example of an alphanumeric grid reference identifying the summit of Ben Macdui, in the Cairngorm Mountains (found on Landranger Map 36), would be NN989989. This is a unique, 100m accurate grid reference which is made up of three elements:

  • NN indicates the 100km x 100km grid square;
  • 989 are the eastings;
  • 989 are the northings.

This would be represented by the 12 figure grid reference 298900.798900

As demonstrated earlier the initial numbers of the Easting and Northing are shown in the corners of all OS maps so it is relatively simple to create a 12-figure grid reference of all locations within the UK. This can then be used within MDTs to find a location on a map and vice versa.

The Global Positioning System (GPS)

By default, most GPS devices will use the projection WGS84. This is a spherical projection and is expressed in latitude and longitude. It is difficult to translate these in the field to paper-based OS maps, so it is recommended that all GPS devices are set to use the British national grid projection which will then display either as alphanumeric values or in the 12-figure grid format previously described.

8B4.68 GPS uses the known position of satellites that orbit the earth, and by using triangulation, or contact with three of these satellites, a receiver can accurately calculate its position on the Earth's surface.

GPS receivers have a number of capabilities including:

  • Give an exact location, time and elevation
  • It can plot movement on the surface or in the air
  • Identify speed of travel
  • Give time, distance and direction to other positions on the landscape
  • Record information on time, distance and direction journeys made
  • Store topographical mapping

8B4.69 The use of the Global Positioning System (GPS) has become common. With the development of small and highly-efficient GPS receivers, GPS is becoming relied upon more and more.

8B4.70 In connection with wildfire, it can provide invaluable information that can aid recognition of ones position on the landscape and assist in navigating across it. GPS can also plot your location and transmit this information to others, this intelligence can be used to improve safety, and assist in controlling operational resources that may be dispersed across wide areas. FRSs should exploit this technology to its full potential and incorporate its use into FRS systems whenever possible. GPS is a useful aid; it cannot provide the field skills and knowledge necessary to operate efficiently within a spatial operational environment.

Plate B4.1

Time given in hours, minutes and seconds at given speed

Pacings based on 62 double pacings per 100 metres speed in kph

Distance (m)

Paces

5 kph

4 kph

3 kph

2 kph

1 kph

50

31

0:00:36

0:00:45

0:01:00

0:01:30

0:03:00

100

62

0:01:12

0:01:30

0:02:00

0:03:00

0:06:00

200

124

0:02:24

0:03:00

0:04:00

0:06:00

0:12:00

300

186

0:03:36

0:04:30

0:06:00

0:09:00

0:18:00

400

248

0:04:48

0:06:00

0:08:00

0:12:00

0:24:00

500

310

0:06:00

0:07:30

0:10:00

0:15:00

0:30:00

600

372

0:07:12

0:09:00

0:12:00

0:18:00

0:36:00

700

438

0:08:24

0:10:30

0:14:00

0:21:00

0:42:00

800

496

0:09:36

0:12:00

0:16:00

0:24:00

0:48:00

900

558

0:10:48

0:13:30

0:18:00

0:27:00

0:54:00

1,000

620

0:12:00

0:15:00

0:20:00

0:30:00

1:00:00

2,000

1240

0:24:00

0:30:00

0:40:00

1:00:00

2:00:00

3,000

1860

0:36:00

0:45:00

1:00:00

1:30:00

3:00:00

4,000

2480

0:48:00

1:00:00

1:20:00

2:00:00

4:00:00

5,000

3100

1:00:00

1:15:00

1:40:00

2:30:00

5:00:00

Plate B4.2

Approximate speeds for given terrain

5 kph

Hard, level surface

4 kph

Variable, rough surface

3 kph

Soft ground, strong headwind, wearing structural firefighting PPE

2 kph

Severe head wind

Time to add for given ascent/descent

1 min per 10m ascent

10 min per 100m ascent

1 min per 20m descent

Time to add for other conditions

Night - ½ daytime speed

Heavy load - 1kph less

>20 kg - ½ normal speed

Speed and distance conversions

1 mile

= 1.6km, 1km = 0.6 mile

1 mph

= 0.4 m/s

= 1.5 ft/s

1,000 ft

= 305m, 1,000m = 3,281 ft

Pacing is based around an average of 62 double paces; adjustments will have to be made to compensate for terrain and ground conditions. With experience, pacing can be extremely accurate.

8B4 Key Considerations

  • An understanding of maps provides useful information relating to the operational environment and the hazards found on the landscape (especially the parts that cannot be seen).
  • Grid references should be given to identify positions on the landscape. When communicating these, they should be repeated by the recipient to confirm understanding.
  • Maps can be used to identify different fuel types found on a landscape. These can change over time, therefore the latest versions of OS maps should be used.
  • Topographical maps can provide invaluable information that can assist when formulating a safe suppression plan.
  • Teams committed on to the fire ground should have, or be supervised by, personnel who have
    an appropriate understanding of navigation.
  • Maps can be used to identify travel times, distances and the safe routes to be taken by operational personnel.
  • Contour lines can be used to identify areas such as steep slopes, gullies and re-entrants,
    where fire behaviour may be more dangerous.
  • Contour lines show the shape of the landscape and this information is essential when
    using the Wildfire Prediction System (WPS).
  • Understanding how to utilise the information on a map is a key skill that improves safety, resource management and assists in the decision making process.

Contact

Email: Dean Cowper