What cabin altitude is targeted to minimize hypoxia risk for most aircrew?

• A. Approximately 8,000 feet cabin altitude or lower
• B. Above 12,000 feet cabin altitude
• C. 15,000 feet cabin altitude
• D. 3,000 feet cabin altitude

Answer: (A)

Hypoxia risk rises as cabin altitude increases because the same percentage of oxygen is delivered at lower pressure, so less oxygen reaches the bloodstream. To keep most aircrew safe during routine tasks, cabin altitude is kept as low as practical. About 8,000 feet cabin altitude or lower provides enough oxygen to maintain alertness and performance for the majority of crew under typical workloads. Higher levels, especially above 12,000 feet, reduce oxygen availability enough that hypoxia symptoms can appear more readily, and at around 15,000 feet the risk becomes significant without supplemental oxygen. A cabin altitude of 3,000 feet is lower than what is normally used and would impose unnecessary operational constraints, while still safety-minded, so the practical target remains near 8,000 feet or lower.