Which agent is preferred for interior fires?

• A. Water
• B. Foam
• C. Dry chemical
• D. Dry powder

Answer: (A)

Interior fires require rapid cooling of the burning materials, and water does this best. Its high heat absorption soaks seat cushions, upholstery, carpeting, and structural components, dropping temperatures quickly and penetrating into hidden pockets. This cooling slows or stops the spread and helps prevent reignition, which is crucial in a confined cabin where occupants may be nearby. Foam can be helpful on hydrocarbon fuel fires, but inside the aircraft cabin its residues and potential to obscure vision make it less ideal as the primary interior agent. Dry chemical and dry powder extinguishers can suppress small or specific flames, but they leave residues that can damage sensitive equipment and electronics and they don’t provide the sustained cooling needed for mixed interior materials.