What is the warning associated with discharging a portable fire extinguisher in the flight deck?

• A. All flight crew members must wear O2 masks set to 100%
• B. O2 masks are optional
• C. Only the captain needs an O2 mask
• D. No oxygen is required

Answer: (A)

When a portable fire extinguisher is discharged in the flight deck, the agents released can displace or significantly reduce the breathable oxygen and irritate the lungs. To stay safe, every crew member in the flight deck should immediately put on an oxygen mask and set it to 100% oxygen. Delivering pure oxygen ensures each pilot receives enough oxygen to think clearly and act quickly, even if the cabin atmosphere has been compromised by the extinguisher. This protection isn’t limited to one person; all flight crew in the cockpit need oxygen to avoid hypoxia and maintain performance during the emergency.