"Airman" was a former general term used to describe any service members of the Royal New Zealand Air Force.
Since the Air Force was established in 1947, all of the various ranks of "airman" have always included women, and in this context, the word "man" means "human being".
A person with the rank of Airman Basic is typically promoted to the rank of Airman after six months of active duty service in the Air Force, if that member had signed up for an enlistment period of at least four years of active duty.
On the other hand, an enlistee could be promoted to the rank of Airman immediately after completing Air Force basic training (and thus paid somewhat more) given one of several additional qualifications: Those enlistees who have qualified for these early promotions to the rank of Airman are allowed to wear their single airman insignia stripe during the Air Force basic training graduation ceremony at Lackland Air Force Base in San Antonio, Texas.
For Airmen with high aptitudes, some of these training programs include more than one school and take a year or more to complete.