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What is the FAA-recommended PERSONAL minimum for SUPPLEMENTAL OXYGEN at night?

Choices

10,000 ft MSL — same as daytime regulatory minimum.
10,000 ft daytime is regulation minimum, not night personal recommendation.
✓ 5,000 ft MSL.correct
The FAA recommends supplemental oxygen above 5,000 ft MSL at night: even at modest altitudes, hypoxia degrades night vision before any cognitive symptoms appear, because the rod cells are highly sensitive to hypoxia. Regulatory: 14 CFR 91.211 requires O2 for flight crew above 12,500 ft (after 30 min) and at all times above 14,000 ft. PERSONAL minimum at night: many CFIs recommend supplemental O2 above 5,000 ft because rod cells (low-light vision) are very oxygen-sensitive. Night vision degrades 5-10% per 1,000 ft above 5,000 due to hypoxia, even before any cognitive impairment.
3,000 ft MSL.
3,000 is too low to be a useful threshold.
Oxygen is only required above 18,000 ft.
18,000 is regulation for PASSENGERS, not crew minimum.

Why

The FAA recommends supplemental oxygen above 5,000 ft MSL at night: even at modest altitudes, hypoxia degrades night vision before any cognitive symptoms appear, because the rod cells are highly sensitive to hypoxia. Regulatory: 14 CFR 91.211 requires O2 for flight crew above 12,500 ft (after 30 min) and at all times above 14,000 ft. PERSONAL minimum at night: many CFIs recommend supplemental O2 above 5,000 ft because rod cells (low-light vision) are very oxygen-sensitive. Night vision degrades 5-10% per 1,000 ft above 5,000 due to hypoxia, even before any cognitive impairment.

FAA source: AIM 8-1-2, effects of altitude; 14 CFR §91.211 for legal supplemental oxygen requirementsbrowse the reference library →

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Original study question written for this course — representative of FAA knowledge-test topics, not an actual current FAA exam question. Reviewed by a panel of three CFIs + AI review.