With both AC packs inop, what is the maximum dispatch altitude?

• A. Five thousand feet
• B. Twelve thousand feet
• C. Ten thousand feet
• D. Fifteen thousand feet

Answer: (C)

When both AC packs are inoperative, the aircraft can’t rely on the Environmental Control System to maintain cabin pressurization and conditioned air at higher altitudes. Without functioning packs, the cabin cannot be kept at a safe, breathable pressure as you climb, so dispatch must be limited to an altitude where the pressurization system can still safely maintain cabin pressure with the reduced capability. This places a fairly low ceiling on how high you can depart or cruise, and the established limit in this situation is around ten thousand feet.

So, the correct choice reflects staying within that lower altitude band to ensure crew and passengers remain safely pressurized and comfortable. Choices that imply higher ceilings would exceed what the aircraft can safely do without the packs, while a much lower number would be unnecessarily restrictive given the actual margin of safety needed.