If both lanes of an ACSC fail, what is the result?

When both lanes of an Air Conditioning System Controller (ACSC) fail, the result is that the associated pack is lost. The ACSC is responsible for managing the operation of the packs, which are crucial for controlling the air temperature and flow within the cabin. If both lanes fail, the system cannot effectively manage these functions, leading to a loss in the associated pack, which directly impacts the environmental control system's ability to regulate cabin conditions.

In this situation, other systems such as the other ACSC are not capable of taking over the function of the lost pack, as the failure of both lanes indicates a critical fault that affects their ability to communicate or coordinate effectively. The air conditioning packs are not automatically switched to fixed flow rates or temperatures as a compensatory action, rather, they cease to function entirely. Thus, the first option accurately reflects the consequence of a dual-lane ACSC failure.