What is flashover in the context of fire phases?

Flashover is the phenomenon that occurs when the temperatures within a compartment become so high that nearly all the combustible materials within that space reach their ignition point almost simultaneously. This leads to a rapid and intense transition from localized burning to widespread fire, engulfing the entire area.

Understanding flashover is critical for firefighters as it represents a significant shift in fire behavior, indicating a rapid escalation in fire conditions that can create extreme hazards. Recognizing the signs of flashover and knowing how to respond can be crucial for safety and effective firefighting strategies.

The other options describe different aspects of fire behavior or conditions that do not accurately define flashover. For instance, the sudden spread of fire to adjacent materials typically occurs prior to flashover and does not encompass the characteristic mass ignition of all combustible materials. The concepts of gradual cooling or the removal of heat pertain to fire suppression and management, rather than the transformational phase that flashover represents.