What action is NOT recommended immediately prior to flashover?

Entering the structure is not recommended immediately prior to flashover due to the extreme danger it poses to firefighters. Flashover is a rapid transition of a fire, where all combustible materials in a room ignite almost simultaneously, creating a lethal environment. At this critical point, the temperature can soar to levels that are immediately life-threatening, and the toxic smoke can drastically reduce visibility and inhalation safety.

In contrast, applying water from a safe distance helps cool the environment and can prevent the flashover by controlling the heat levels. Using a thermal imager allows firefighters to detect hot spots and assess the behavior of the fire without putting themselves in immediate danger. Assessing fire behavior is crucial for understanding the dynamics of the fire and making informed decisions about firefighting tactics. Therefore, entering the structure is the least safe and most ill-advised action when flashover is imminent.