What is the maximum altitude for CRJ 900 operations without oxygen?

The maximum altitude for CRJ 900 operations without supplemental oxygen is indeed 14,000 feet. At this altitude, the risk of altitude-related physiological effects, such as hypoxia, significantly increases. The Federal Aviation Administration (FAA) regulations state that supplemental oxygen is required for pilots above 12,500 feet cabin altitude for more than 30 minutes and mandatory for all occupants if the altitude exceeds 14,000 feet. Therefore, 14,000 feet serves as a critical threshold for safe operations, ensuring that both crew and passengers are adequately protected against the effects of reduced oxygen levels.

Choosing this altitude reflects an adherence to safety standards that prioritize health and operational effectiveness during flight. The other altitude options represent lower cutoffs, and while supplemental oxygen may not be mandatory below those levels, they do not align with the regulations that define the 14,000-foot limit as the maximum altitude for operation without oxygen.