This cult favorite first appeared in 1916, in "Recipes for Mixed Drinks", by Hugo Ensslin, head bartender at Times Square’s Hotel Wallick. Ensslin’s original formula called for the drink to also include crème de violette, which tints the drink a light sky blue. It is Harry Craddock's "Savoy Cocktail Book" from 1930 in which we find the version of the Aviation without the crème de violette, but otherwise it is the exact same recipe as Mr. Ensslins.
The original 1916 recipe called for 2 parts gin, 1 part lemon juice, 2 dashes of Maraschino liqueur, and 2 dashes of crème de violette.
To approximate Ensslin’s original formula, mix 2 oz (60 ml) gin, 0.5 oz (15 ml) lemon juice, 2 tsp maraschino liqueur and 1 tsp crème de violette.