FIRE STRUCTURE (Courtesy of CSIRO Bushfire Behaviour and Management Section)
Heading Fire A heading fire is one where the flames are blown towards unburnt fuel.
The fuel bed is ignited at the top and burns progressively down into the
lower layers. A heading fire, particularly under extreme conditions, can
be quite inefficient in its combustion, resulting in thick black smoke
and partially burnt fuel. Large envelopes of burning gas can be quite often
seen as flashes of flame well above the average flame height.
Flanking Fire
The edge of a flanking fire
is generally aligned parallel to the direction of the wind. Flames more or less
lean along the flank. Due to the ever changing nature of the wind, slight
changes in wind direction means that the flank will become, by turns, a heading
fire and a backing fire in response to the changes in wind direction. Therefore
a flank may exhibit the high flames and black smoke of a heading fire one
moment, and the low flames and little smoke of a backing fire the
next.
Backing Fire
A backing fire is one which moves into the wind. The flames lean over already
burnt ground and ignite the fuel at the bottom of the fuel bed. The rate
of spread of a backing fire is quite slow and independent of the wind speed.
Combustion is often very efficient and complete, resulting in less smoke
than a heading fire and, in some fuel types, a fine white ash residue.
At different times in the development of a fire, heading fires, backing
fires and flanking fires may occur at any location around the fire perimeter,
depending on the fluctuations in the direction of the local wind at the
fire edge. The local wind results from the interaction between the prevailing
wind and the convective updraft of the whole fire. During a lull in the
prevailing wind, the convection from the fire may draw wind towards the
fire centre so that a backing fire may occur around the entire perimeter.
WATCHOUT
Weather : dominates fire behaviour, so keep informed. Actions : must be based on current and expected fire behaviour. Try out : at least two escape routes. Communicate : with your officer in charge, your crew and adjoining crews. Hazards : beware of variations in fuels, slopes. Observe : changes in wind speed or direction, temperature, humidity and cloud. Understand : your instructions, make sure that you are understood. Think : clearly, be alert and act decisively before your situation becomes critical
INDICATORS OF EXTREME FIRE BEHAVIOUR
A rapid increase in the fires intensity.
High sustained rate of fire spread.
Well developed convection column.
Long distance spotting - over 180 metres.
Fire whirlwinds or horizontal flame sheeting.
Sudden calming of the wind.
EQUIPMENT
Name
Description
Call sign
People
Water (l)
Photo
SOU/C
Command vehicle
Southern Command
5
0
SOU 10
Heavy Tanker
(Cat1)
Southern One Zero
5
3600
SOU 11
Heavy Tanker
(Cat1)
Southern One One
5
3200
SOU 20
Light Unit
(Cat9)
Southern Two Zero
2
500
SOU 21
Light Unit
(Cat9)
Southern Two One
2
500
SOU 30
Medium tanker
(Cat7)
Southern Three Zero
3
1600
SOU 31
Medium tanker
(Cat7)
Southern Three One
3
1600
SOU 40
Quick Fill
Southern Four Zero
0
0
The vehicles also carry a lot of other equipment, such as:
Rake Hoes;
Back Packs;
Chainsaw and protective gear;
Axe;
Shovel;
Driptorches and fuel;
Class A Foam;
Standpipes;
Hydrant bars;
Hose of various diameters;
Nozzles;
First aid kit
Hooligan Tool
COMMUNICATIONS
ACT RFS vehicles are equipped with a number of communication systems.
ACT Trunked Radio Network (TRN) - Primary System
The TRN is a Motorola Smartzone APCO25 digital system. Being a digital
system it provides very clear communications where there is coverage. Repeaters
are located on Mt Ainslie, Black Mountain, One Tree Hill, Tuggeranong Hill,
Bulls Head, Mt Stromlo, Mt Jerrabomberra, Mt Ginini, Mt Tennent and Mt
Clear. Because the TRN is actually Zone 3 of the NSW GRN system it provides
interoperability with NSW RFS brigades via the ESLO and PMR channels ,
an advantage over the old VHF system. The TRN system also provides simplex
channels for talk around. The TRN hand held radios also have UHF CB channels
programmed.
VHF Bushfire Radio - Secondary System
This is an analogue repeater system on the VHF band. Provides good coverage over most of the ACT except some of the southern areas of Namadgi National Park. Repeaters are located on CH1 - Isaacs Ridge, CH2 - Bulls Head, CH3 - Baldy Hill, CH4 - Mt Tennent, CH5 - Portable Repeater, CH6 - Black Mountain, CH7 - Camel Back, CH8 - Mt Pierce, CH9 - Mt Booth and CH10 - Googong. The system also has a number of simplex channels used for talk around and local communications.
Southern Local
A simple VHF radio with a repeater located on Mt Tennent. Local radios are also installed in local land-holders vehicles. Land-holders are equipped with slip on units for rapid response to small fires on their or neighbours properties.
A heading fire is one where the flames are blown towards unburnt fuel.
The fuel bed is ignited at the top and burns progressively down into the
lower layers. A heading fire, particularly under extreme conditions, can
be quite inefficient in its combustion, resulting in thick black smoke
and partially burnt fuel. Large envelopes of burning gas can be quite often
seen as flashes of flame well above the average flame height.
At different times in the development of a fire, heading fires, backing
fires and flanking fires may occur at any location around the fire perimeter,
depending on the fluctuations in the direction of the local wind at the
fire edge. The local wind results from the interaction between the prevailing
wind and the convective updraft of the whole fire. During a lull in the
prevailing wind, the convection from the fire may draw wind towards the
fire centre so that a backing fire may occur around the entire perimeter.
