General Authority of Civil Aviation (GACA) Aeronautical Information Publication (AIP) Practice Exam

If one pack is in standby cooling and the other is operating normally, what occurs?

1. The pack in standby will shut down at lower altitude and higher temperature

2. Both packs will operate at maximum efficiency

3. The standby pack continues to operate with limited functionality

4. The operating pack will automatically switch to standby mode

The correct answer is: The pack in standby will shut down at lower altitude and higher temperature

In the scenario where one pack is in standby cooling and the other is operating normally, the standby pack is designed to conserve energy while ensuring that cooling remains available if needed. If the aircraft ascends to a lower altitude or experiences a higher ambient temperature, the system is programmed to prioritize efficiency and may cause the standby pack to shut down in order to prevent unnecessary energy usage and to maintain overall performance. This mechanism is crucial for the efficiency and safety of the aircraft's environmental control system. By shutting down the standby pack at lower altitudes and higher temperatures, the aircraft reduces the workload on the cooling system, allowing the operating pack to maintain optimal environmental conditions for passengers and crew. In such a setup, choices describing both packs operating at maximum efficiency or switching operational modes do not accurately reflect the intended operational protocols of the system. The standby pack is explicitly designed to limit its function while in standby to conserve resources, making it less likely to operate at full capability until the primary system needs assistance.