What is the difference between Class A and Class B fires in aviation terms?

• A. Class A involves ordinary combustibles; Class B involves flammable liquids; follow appropriate extinguishing guidance.
• B. Class A involves electrical equipment; Class B involves cooking oils; use water for both.
• C. Class A is for metal fires; Class B is for chemical fires; use sand for both.
• D. Class A is for fires involving waste paper; Class B is for electrical fires; use CO2 for Class A only.

Answer: (A)

The main idea is that fires are categorized by what is burning, and the extinguisher choice depends on that fuel type. Class A fires involve ordinary combustibles like paper, wood, textiles, and trash, which are effectively cooled and smothered with water-based agents (water or foam) to absorb heat and prevent reignition. Class B fires involve flammable liquids such as aviation fuel and oils, which must be tackled with agents that can blanket or displace the liquid and cool it, like foam, dry chemical powders, or CO2; using water on a liquid fuel fire can spread the flames. The statement captures this distinction and stresses following the right extinguishing guidance for each class.

The other options mix up what constitutes each class or suggest inappropriate methods, such as applying water to liquid fires or mislabeling the fuels, which would not be effective or could be dangerous.