For fire extinguishing purposes under Index A, what is the combined weight of sodium-based dry chemical or equivalent needed?

The combined weight of sodium-based dry chemical or equivalent needed for fire extinguishing purposes under Index A is correctly identified as 500 pounds. This standard is derived from fire protection guidelines and regulations that specify the minimum amount of extinguishing agent required to effectively suppress fires in the context of airport firefighting operations.

In the case of Index A, which applies to aircraft fires and emergency situations involving fuel hazards, a sufficient amount of the extinguishing agent is crucial for ensuring quick and efficient control of fires. The quantity of 500 pounds has been established as effective for addressing typical fire scenarios encountered in these settings, counting on the agent's capacity to suppress flames and prevent fire re-ignition.

Understanding the need for the specified weight helps to ensure that firefighting teams are properly equipped to respond to emergencies with adequate resources for effective mitigation of fire hazards.