Name one component of an aircraft's environmental control system.

The air conditioning pack is a key component of an aircraft's environmental control system. It is specifically designed to regulate the cabin temperature and maintain a comfortable environment for passengers and crew during flight. The air conditioning pack works by cooling or heating the air, controlling humidity levels, and ensuring a stable air pressure within the cabin.

This system is critical for long flights where external temperatures and pressure conditions can fluctuate significantly. Proper functioning of the air conditioning pack contributes to the overall safety and comfort of the flight operation, making it an essential component of the environmental control system. In contrast, components like hydraulic pumps, fuel tanks, and navigation systems perform different functions related to flight mechanics, fuel management, and aircraft navigation, respectively, rather than managing the cabin environment.