If both air conditioning packs are OFF during flight, what is the likely effect?

• A. Cabin temperature remains unchanged.
• B. Engine power automatically increases.
• C. Cabin temperature rises and environmental comfort is reduced.
• D. Aircraft automatically descends to a lower altitude.

Answer: (C)

When the air conditioning packs are OFF, the cabin loses its source of conditioned air. The environmental control system relies on those packs to cool or heat the air to a comfortable temperature. Without them, the cabin air isn’t actively temperature-controlled, so heat produced by passengers, crew, and equipment (and even solar gains) accumulates. That leads to the cabin warming up and environmental comfort decreasing. The other effects listed aren’t linked to turning off the packs—engine power isn’t automatically increased, and the aircraft won’t descend automatically due to this change.