Which option correctly states the three Flight Deck oxygen modes?

• A. Normal, 100%, Emergency Mode
• B. Normal and Emergency
• C. 100% and Emergency
• D. Normal, 100%, Standby

Answer: (A)

There are three operating positions for the flight deck oxygen system: Normal, 100% oxygen, and Emergency Mode. Normal mode provides oxygen through the regulator as needed for standard operations. 100% mode delivers full-oxygen concentration when a higher supply is required, such as at higher altitude or when rapid decompression is a concern. Emergency Mode activates the emergency oxygen supply to provide high-flow oxygen to the crew for a limited period during critical situations like loss of cabin pressure or smoke in the cockpit.

This is why the stated option is correct: it lists Normal, 100%, and Emergency Mode—the complete set of flight deck oxygen modes. Other options omit one of these modes or include Standby, which isn’t a flight deck oxygen mode.