Cockpit Oxygen Masks

Going through the FAR,

91.211 Supplemental Oxygen.
Part (b), Paragraph (1), Section (ii)

“No person may operate a civil aircraft of U.S Rigistry with a pressurized cabin at altitudes above flight level 350 unless one pilot at the controls is wearing and using an oxygen mask that is secured and sealed and that either suppllies oxygen at all times or automatically supplies oxygen whenever the cabin pressure altitude of the airplane exceeds 14,000 feet (MSL), except that the one pilot need not wear and use an oxygen mask while at or below flight level 410 if there are two pilots at the controls and each pilot has a quick donning type of oxygen mask that can be place on the face with one hand from the ready position within 5 seconds, supplying oxygen and properly secured and sealed.”

Does this apply to flying for the airlines? I’m asking because I never envisioned an airline pilot in the cockpit with a quick donning mask hanging off them. Thanks for any reply!


I can answer as an aircraft mechanic in the Air Force we maintained the quick don masks in the cockpit. They hung just behind each pilots seat on the KC-135 and could easily be pulled down for use in the event of an emergency. The were hooked into the emergency oxygen system on the aircraft. I do know that at higher altitudes when one pilot left the cockpit the remaining pilot in the cockpit would wear the oxygen mask.

I know it’s not an airline but I’m sure it’s a somewhat similar situation.



Below FL 410 (which we never go above) one pilot must wear the oxygen mask when the other pilot leaves the cockpit. It is a pain and quire honestly I think it is gross, but we do it. Supposedly the rules are changing soon and this requirement will be relaxed.

Some of the newer masks have smoke goggles attached to them, which could be a really good thing in an emergency,



It absolutely applies to the airlines and yes when one pilot leaves the cockpit the other pilot will don their mask and wear it until the other pilot returns. While many pilots don’t like the reg it’s actually a really good idea. The ICAO states the Time of Useful Consciousness at FL400 is 15-20secs. Problem is if the aircraft experiences an explosive depressurization that time is cut in half bringing it down to 7.5-10secs. Subtract a sec or 2 for not being at optimum health, startle or it being 2am and you get awfully close to that 5 secs it takes to get the mask on leaving no one awake to deal with the emergency. No bueno.


Thank you for the reply all! Is the mask typically just standard equipment that comes with the aircraft, or do you purchase one and keep it in your flight bag?


The planes are all equipped with the required masks. It’s actually a pretty complicated setup.

And yes, that means EVERYONE is sucking on the same mask hence Chris’ dislike.




They are attached to the airplane.

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