[pants2]

TIL that pilots can't have a full beard because oxygen masks can't make a seal. Guess that's where the pilot moustache stereotype comes from.

[mfkp]

This actually isn't the case anymore, plenty of non-US airlines allow beards and the new masks still provide perfect oxygen flow. It's more of a "professional image" thing in the US.

[gnabgib]

Good mask fit came up a lot during Covid. Moustaches can interfere too (depending on size, and mask shape)