Q. I was recently confronted with the question a versus an. We used a; he insisted it should be an. In the 15th edition, in section 15.9, it shows that “when an abbreviation follows an indefinite article, the choice of a or an is determined by the way the abbreviation would be read aloud.” In the examples used, it shows “an NBA coach.” Why would you not use a there? “An National Basketball Association coach” doesn’t seem correct to me.
A. “NBA” is not pronounced “National Basketball Association” but “en-bee-ay.” Thus, “an NBA coach.” (See CMOS 10.9.)