air crew vs crew

air crew and crew both are nouns.

Word	Noun	Adjective	Verb	Adverb
air crew	Yes	No	No	No
crew	Yes	No	Yes	No

As nouns, crew is a hypernym of air crew; that is, crew is a word with a broader meaning than air crew:

air crew (noun)	crew (noun)
the crew of an aircraft	an organized group of workmen
	the men and women who man a vehicle (ship, aircraft, etc.)
	the team of men or women manning a racing shell
	an informal body of friends

air crew (verb)	crew (verb)
	serve as a crew member on