During a flight above 35,000 feet MSL, what is required for at least one pilot at the controls?

• A. No oxygen mask is required
• B. At least one pilot must wear an oxygen mask as specified for high altitude operation
• C. Only cabin crew need oxygen masks
• D. Oxygen masks are optional at the team's discretion

Answer: (B)

High-altitude flight makes hypoxia a real risk, so pilots must have ready access to supplemental oxygen. At about 35,000 feet, the safety standard requires that at least one pilot at the controls is wearing an oxygen mask to ensure the pilot remains oxygenated and able to manage the aircraft, even in case of a depressurization or other issue. The mask type and usage are defined for high-altitude operation to ensure reliable oxygen delivery.

That’s why this option is the right choice: it reflects the mandatory use of an oxygen mask by at least one pilot at the controls during high-altitude operations. The other choices miss the safety and regulatory requirement—oxygen isn’t optional, and both pilots and crew at risk should have access to and use oxygen when needed.