At what cabin pressure altitude must occupants be provided supplemental oxygen in a civil aircraft of US registry?

At what cabin pressure altitude must occupants be provided supplemental oxygen in a civil aircraft of US registry?

• A. 10,000 feet MSL
• B. 12,000 feet MSL
• C. 15,000 feet MSL
• D. 18,000 feet MSL

Answer: (C)

Oxygen requirements in flight are tied to cabin pressure altitude to guard against hypoxia as the air gets thinner. There are two related rules: once the cabin pressure altitude exceeds 12,000 feet, the flight crew must use supplemental oxygen, and once the cabin pressure altitude exceeds 15,000 feet, supplemental oxygen must be provided to all occupants on board. So, the point at which everyone on the airplane must be provided oxygen is 15,000 feet MSL. This ensures that even passengers who may not recognize symptoms of hypoxia still have access to oxygen when the air is too thin.

Oxygen requirements in flight are tied to cabin pressure altitude to guard against hypoxia as the air gets thinner. There are two related rules: once the cabin pressure altitude exceeds 12,000 feet, the flight crew must use supplemental oxygen, and once the cabin pressure altitude exceeds 15,000 feet, supplemental oxygen must be provided to all occupants on board. So, the point at which everyone on the airplane must be provided oxygen is 15,000 feet MSL. This ensures that even passengers who may not recognize symptoms of hypoxia still have access to oxygen when the air is too thin.