Definition
The act of putting on an oxygen mask correctly and quickly so that supplemental oxygen begins flowing to the pilot. In high-altitude operations, donning includes securing the mask to the face, ensuring a proper seal, selecting the correct oxygen flow setting, and verifying that oxygen is actually being delivered before continuing flight duties.
Plain English
Putting on your oxygen mask the right way, fast, and confirming it's working.
Context Anchor
Seen in high-altitude operations, emergency training, and crew procedures for pressure loss, smoke, or oxygen use.
Derivation
Don' comes from the older English contraction of 'do on' -- meaning to put on (clothing or equipment). The opposite is 'doff' (do off). The word is used here in its traditional sense of putting equipment on quickly and correctly.
Why Pilots Care
Rapid and correct donning prevents hypoxia, maintains pilot decision-making ability, and fulfills regulatory requirements for flight above certain altitudes.
Grounding Statement
In an emergency, the useful action is not finding the mask—it is getting it sealed on your face and breathing from it.
Intuition Check
Do not read “donning” as simply “having the mask ready.” In this context, it means putting the mask on correctly and starting to use it.
Example Sentence 1
FAA regulations require that one pilot wear an oxygen mask above FL350 when the other leaves the controls, so rapid donning of oxygen masks is a regularly practiced skill.
Example Sentence 2
The crew practiced donning of oxygen masks after a simulated rapid decompression.