What is the earliest phase of fire that starts with ignition?

The incipient phase is the earliest stage of a fire, beginning with ignition. This phase is characterized by the initial development of the fire, where the flames are small, and the heat release is relatively low. During the incipient phase, the fuel that has ignited continues to burn and generate combustion products, but it has not yet reached a size or intensity that poses a significant threat.

Understanding this phase is crucial for effective fire prevention and response strategies, as it represents the best opportunity for extinguishing the fire before it spreads. The flames may not be visible, and the fire can often be extinguished easily with a portable extinguisher or other means.

In contrast, the growth phase involves the expansion and increased intensity of the fire as it spreads to additional fuels and generates more heat. The decay phase refers to the stage when the fire starts to weaken and burn out due to the depletion of fuel or oxygen. The fully developed phase is when the fire reaches its maximum intensity, often becoming uncontrollable. Each of these phases follows the incipient phase and requires different tactical approaches for effective management.