An indefinate article identifies a noun. "A" is used before nouns that start with a consonant or consonant sound.. "An" is used before nouns that start with a vowel. Therefore, I would say "an apple" and "a car". But because the indefinite article identifies the noun, if an adjective is in between them, I do not consider it when selecting an identifier. Therefore, I would say "a ample portion" and "an stinky elephant". I know it sounds stupid when you say it or write it, but that is part of the reason why I remember it so well. I know I am not alone on this, because I see it very occasionally. Did I make this up? The specific example we were debating is "an public utility". (I know that "utility" has a consonant sound, but I learned that from trying to find an answer for this question on your website!)

The one-word spelling alright appeared [1887] some 75 years after all right itself had reappeared from a 400-year-long absence. Since the early 20th century some critics have insisted alright is wrong, but it has its defenders and its users. It is less frequent than all right but remains in common use especially in journalistic and business publications. It is quite common in fictional dialogue, and is used occasionally in other writing: "the first two years of medical school were alright -- Gertrude Stein."