In which stage of the burning process does flashover occur?

Flashover is a critical phenomenon in fire behavior where the temperature in a space becomes sufficiently high, causing rapid combustion of combustible materials and the simultaneous ignition of everything in the area. This event marks a significant transition in the progression of a fire, leading to an intense increase in both heat and flame.

In the context of the stages of fire, flashover typically occurs in the transition from the initial growth to the fully developed stage. It signifies a point where the fire has grown sufficiently and the conditions are ripe for a sudden and dramatic escalation in the rate of combustion.

During the fully developed stage, the fire has reached its peak intensity, and the environment has been sufficiently heated. The fuel load in the area is at a critical temperature, and when a new source of oxygen becomes available, or simply due to the heat itself, the surrounding materials will ignite almost simultaneously. This makes the fully developed stage the correct answer for where flashover is most likely to occur, as it indicates all conditions necessary for this rapid and catastrophic increase in the fire's behavior are met.

Understanding the timing and conditions of flashover is essential for fire suppression tactics, informing firefighters of the immediate threats posed by rapidly escalating fire conditions.