What is the minimum oxygen quantity for two crew members?

• A. 800 PSI
• B. 960 PSI
• C. 1000 PSI
• D. 1100 PSI

Answer: (B)

The main idea is oxygen supply planning: two crew members need a sufficient amount of oxygen to last for the required emergency duration given the regulator’s flow rate. A compressed oxygen cylinder has a fixed amount of gas that’s available as pressure drops. The figure of 960 psi represents the lowest pressure at which the remaining gas is enough to feed both regulators for the mandated time. Beyond this point, you’d risk running out before you can reach a safe condition or complete the emergency steps. The other pressures would either be more than the minimum needed, or fall short of what’s required to guarantee the minimum duration. So 960 psi is the threshold that ensures adequate oxygen for two crew under the test conditions.