Committing crews to offensive operations requires the adoption of a safe system of work that reduces the risks to firefighters to a level as low as is reasonably practicable. If an incident commander has insufficient personnel present to introduce such a system of work, they may have to adopt defensive tactics until further resources arrive, or until they are reasonably certain that further resources will arrive imminently.
Rescue operations must be the subject of a dynamic risk assessment, balancing the benefits in terms of saveable life against the risk to firefighters.
See National Operational Guidance: Incident Command
Where signs and symptoms suggest the likelihood of a backdraught, consideration should be given to employing defensive firefighting tactics until further resources, or special equipment such as cutting extinguisher or positive pressure ventilation, can be brought to the incident. Incident commanders must ensure they have considered the likely outcome of ventilating a compartment before opening it up for firefighting.
Incident commanders must assess the growth stage of the fire when deciding to commit crews to offensive operations. If rapid intervention with a sufficient application rate of firefighting media can be made, a flashover may be forestalled. However, compartment size, the presence of fire and fire gas spread in voids, fire loading and poor application rates may make this tactic untenable.
At high-rise fires or wildfires, fire may be wind-driven. The effect of high wind speeds on a fire may prevent rapid intervention and, particularly in the case of high-rise fires, require incident commanders to adopt specific tactics to prevent uncontrolled firespread and injury to firefighters. These tactics are likely to require a large number of resources be assembled before committing to offensive firefighting.
When fighting fires in the open, the incident commander should deploy firefighters with due regard for the likely effect of topographical features on firespread. Although wind direction and the presence or absence of vegetation are the key factors in firespread, other features may produce unexpected changes in fire behaviour leading to crews being overtaken. Fires tend to spread more quickly uphill, due to preheating of fuel, and more slowly downhill. Underlying root structures and soil types may cause fire to spread unseen, and the relative moisture content of different types of vegetation may produce unexpected patterns of firespread.
See National Operational Guidance: Wildfires
See National Operational Guidance: Incident command – Command decision-making