The situation remains very worrying on the fire front, even if the fire remained “generally stable” overnight, the Gironde prefecture announced on Monday July 27. In the departments, flames have ravaged 42,000 hectares since Wednesday and led to the evacuation of hundreds of thousands of people.
“Line of fire”, “out of control”, “fixed”… To talk about the fires they fight, fire fighters use their own vocabulary. These terms allow intervention teams to quickly communicate the status of the disaster and the strategy to adopt.
Types of fires
A fire is a race against time. When it is in its initial phase, we speak of “incipient fire”. It is characterized by point flames and limited heat. To prevent it from spreading, the firefighters must be notified at this stage. If the fire takes hold and the flames become more vigorous, we speak of an active fire. We must then begin to secure the perimeter in order to protect people.
Fire can take several forms. When the combustion is hidden under the surface (peat, pile of branches), without visible flames, we enter a smoldering fire. To extinguish it, you must then inspect the ground, dig it with rakes and water it thoroughly to eliminate all the embers. The surface fire travels close to the ground on the litter (dry grass, dead leaves). Conversely, crown fire spreads high into the canopy. A fire can, however, accumulate different types of fires depending on the areas.
Means of struggle
To act effectively, firefighters have specific methods and tools. Direct attack tactics include all actions carried out in immediate contact with the disaster. Typically, firefighters advance a hose in hand to send a concentrated stream of water directly onto the flame front. They will therefore try to drown the fire by massively flooding the hearth or by spreading foam to lower its temperature and deprive it of oxygen.
On the other hand, indirect attack methods take place at a distance from the blaze. The goal of firefighters is to have a well-defined line of fire to fight the fire. It is a barrier, natural or artificial, which prevents the spread of flames. To achieve this, they can set up a firebreak by stripping or regularly watering a strip of land.
To further weaken the disaster, if weather conditions permit, they trigger a counter-fire in front of the main front in order to consume the residual fuel or start controlled fires to reduce in more distant sensitive sectors. Planes or helicopters are sent to waterbomb the area to increase the efficiency of the overall operations.
Mastery stages
To describe the evolution of control, firefighters use stages HC, C, M and E. “Out of control” means that no perimeter has yet been established and the flames are progressing freely. Firefighters then assess the emergency situation, secure the threatened areas and work to contain the disaster as much as possible. The goal is to stop the fire, this means that the fire is still in progress but is no longer advancing, because its axis of propagation has been stopped. The critical phase is therefore over.
When the fire is “contained”, this means that the deployed resources have stabilized the front and prevented any spread beyond the perimeter where the fire is already present. The priority is then to consolidate fire lines, water buffer zones and protect easily flammable parts. The fire was contained when the firefighters managed to completely surround it to prevent any recurrence.
At the “controlled” stage, all the lines hold and the fire no longer spreads. Teams go into active surveillance and focus their efforts on cooling hot spots. Finally, when it is “off”, there is no longer any combustion or embers. Firefighters carry out safety inspections. It will then be time to raise the alert and put away the equipment.
