When must ARFF personnel sound a proper withdrawal signal?

The correct response is that ARFF personnel must sound a proper withdrawal signal when munitions become involved in a fire. This is crucial because the presence of munitions significantly escalates the hazard level of a fire situation. As munitions can explode or become unstable under certain conditions, the safety of firefighting personnel and civilians is paramount. Sounding a withdrawal signal under these circumstances alerts personnel to evacuate the immediate area to avoid potential harm from explosions or shrapnel.

The other scenarios, although they may warrant a change in tactics or procedures, do not specifically necessitate the immediate withdrawal of ARFF personnel in the same way. For instance, when the fire is under control, or when additional resources are needed, personnel may adjust their approaches without the urgency that the involvement of munitions presents. Furthermore, when the fire is extinguished, personnel are typically in a recovery or overhaul phase rather than an immediate withdrawal, as there is no longer an active threat requiring evacuation. Thus, the correct identification of the need for a withdrawal signal in the presence of munitions underscores the critical focus on safety in emergency response operations.