AFFF is primarily chosen for airport firefighting because of its ability to...

• A. Form a quick-burning film to spread flames.
• B. Seal and suppress fuel vapors, provide cooling, separate combustibles, and resist breakdown from other chemical agents.
• C. Create high expansion foam only.
• D. Be used with dry chemical to form multi-agent foam.

Answer: (B)

AFFF is chosen for airport firefighting because its foam forms a protective film on the fuel surface that seals in vapors, cools the fuel, and creates a barrier between the fuel and the air. This vapor-sealing action greatly reduces the flammable vapor that can feed the fire, while the water content in the foam absorbs heat to slow or stop the burning. The foam blanket also helps keep different fuels from coming into contact with each other and the ignition source, aiding in overall fire control. The film remains stable in the presence of common chemical agents found in aviation environments, so the protective layer continues to work as the fire evolves.

The other ideas don’t capture this combination: forming a film that spreads flames would worsen the fire; being used only for high expansion foam ignores AFFF’s role in surface cooling and vapor suppression; and relying on a dry chemical to form a multi-agent foam isn’t the typical use for AFFF in aviation emergencies.