Steven P. McNicoll wrote:


(ii) At flight altitudes above flight level 350 unless one pilot at the
controls of the airplane is wearing and using an oxygen mask that is secured
and sealed and that either supplies 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
placed on the face with one hand from the ready position within 5 seconds,
supplying oxygen and properly secured and sealed.



I flew on an air ambulance Lear 25 for a while.. and I can say I NEVER
saw the cockpit crew remove the masks from the hangars and place them in
"the ready position" even though we routinely went to FL 450-490. I am
wondering how many operators follow this rule.

Dave