Which system supplies conditioned air to the cabin and cockpit?

• A. Hydraulic system.
• B. Environmental Control System (ECS).
• C. Electrical power system.
• D. Fuel system.

Answer: (B)

The Environmental Control System handles the cabin and cockpit environment. It is responsible for delivering conditioned air—air that has been cooled or heated to a comfortable temperature and then supplied at the correct pressure and flow—to both the cabin and the cockpit. It achieves this by routing bleed air from engines or the APU through air conditioning packs and air cycle machines, controlling temperatures with mixing and cooling, and managing cabin pressure with outflow valves and a pressure controller. This set of functions is unique to the ECS, making it the system that provides the conditioned air you rely on during flight.

Other systems have different roles: the hydraulic system powers flight controls and other mechanical devices, the electrical power system supplies electricity to all aircraft systems, and the fuel system stores and delivers fuel for propulsion and some onboard systems.