When Pack Flow is selected to LO and the temperature demand cannot be satisfied, to which flow does the pack revert?

When Pack Flow is selected to LO, it means that the system is attempting to maintain a lower flow rate for the cabin air. However, if the temperature demand cannot be satisfied—meaning that the cabin temperature is not reaching the required setting—the pack will revert to NORM flow.

This behavior ensures that there is adequate airflow and temperature management in the cabin, preventing the scenario where the airflow is too low to sufficiently cool or heat the space. NORM flow offers a balance, providing more airflow than LO while still being below the maximum HI setting, thus allowing for efficient temperature control without overwhelming the system.

The other options, such as HI, LO, or AUTO, do not represent the standard operational reversion when demand is unmet while operating in LO mode. HI would typically provide maximum flow, which is not the transitional step from LO, and AUTO would vary based on system needs rather than reverting to a set state. Understanding this reversion process is crucial for effectively operating the A320’s environmental control systems.