navigator vs aircrewman

navigator and aircrewman both are nouns.

Word	Noun	Adjective	Verb	Adverb
navigator	Yes	No	No	No
aircrewman	Yes	No	No	No

As nouns, aircrewman is a hypernym of navigator; that is, aircrewman is a word with a broader meaning than navigator:

navigator: the member of an aircrew who is responsible for the aircraft's course
aircrewman: a member of an aircrew

navigator (noun)	aircrewman (noun)
in earlier times, a person who explored by ship	a member of an aircrew
the member of an aircrew who is responsible for the aircraft's course
the ship's officer in charge of navigation