Which venting option is not used by the ACS air system?

The pilot's overhead compartment is not a venting option used by the ACS (Aircraft Comfort System) air system. The ACS is designed to direct airflow to specific areas within the cockpit and cabin to maintain comfort and usability for occupants. The cockpit instrument panel vents, the pilot's feet area, and the cabin foot panel are all strategically placed to ensure adequate ventilation.

The vents at the cockpit instrument panel help provide pilots with cool air and maintain their comfort levels during flight. The pilot's feet area and the cabin foot panel serve a similar purpose, allowing comfortable airflow to the lower sections of the cockpit and enhancing the overall comfort of passengers in the cabin. The overhead compartment, however, is typically not designed for air ventilation, focusing instead on storage and does not incorporate airflow features as part of the ACS. This distinction highlights the aircraft's attention to effective air distribution within the operational areas.