What must you verify about the Lav Fire Extinguisher for the aft lavatory?

Ensuring that the Lav Fire Extinguisher for the aft lavatory is fully charged is crucial for effective emergency response. A fully charged extinguisher indicates that it is equipped with the necessary amount of extinguishing agent to combat potential fires. It ensures readiness in the event of a fire, which can occur due to various factors such as electrical failures or flammable materials being present in the lavatory environment.

In contrast, other factors mentioned do not reflect the state necessary for the extinguisher's functionality in emergencies. For example, if the gauge is in the red zone, it signifies that the extinguisher is either over-pressurized or undercharged, both of which compromise its effectiveness. If the extinguisher has been used recently, it may not contain enough extinguishing agent to be effective in another emergency. Lastly, while keeping the waste container empty is good practice to prevent fire hazards, it does not directly relate to the operational status of the fire extinguisher itself. Thus, confirming that the extinguisher is fully charged is the most critical verification needed.