What is required for complete knockdown of fires?

For achieving complete knockdown of fires, primary extinguishing agents are essential because they are specifically designed for controlling and extinguishing flames effectively. These agents include water, dry chemical powders, and foam agents, which work by various mechanisms such as cooling the fire, smothering the flames, or interrupting the chemical reactions that sustain combustion.

When an aircraft fire occurs, the use of primary extinguishing agents allows first responders to apply a significant and immediate response, targeting the fuel and heat sources directly. This is crucial for not only suppressing the fire but also for preventing re-ignition, which can occur if the fire is not completely extinguished or if secondary sources of ignition are not controlled.

Secondary extinguishing agents, while useful in certain situations to enhance fire suppression, are typically employed after the primary agents have initially addressed the fire. Direct access to the fire source may be necessary in some scenarios, but without the adequate primary agents, simply accessing the fire would not ensure complete knockdown. Lastly, relying solely on fire suppression foams would limit the effectiveness against various fuel types and fire scenarios, underscoring the importance of integrating primary extinguishing agents into a comprehensive firefighting strategy.