Which system extracts air from jet engine compressors for heating, cooling, and pressurizing the aircraft?

• A. Bleed-air system
• B. Air conditioning system
• C. Fuel and bleed air system
• D. Exhaust gas recirculation system

Answer: (A)

Bleed air is compressed air taken from the engine’s compressor stages, used as the source of pneumatic power for heating, cooling, and pressurizing the aircraft. Because this air is hot and dry, it’s routed through the environmental control system where it’s cooled and conditioned by air conditioning packs, then distributed to the cabin. The same bleed air supply also provides the pressurized air for cabin pressurization, with systems like outflow valves regulating the cabin pressure. Anti-icing and other pneumatic needs can also use bleed air.

The air conditioning system itself is what conditions and distributes the air, but the air it uses comes from the bleed air system. Exhaust gas recirculation isn’t involved in supplying cabin air, and a fuel-and-bleed-air system isn’t the standard term for this function.