This is one of four theoretical decklists for a Commander product based on the classic Four Elements: Earth, Water, Air, and Fire. Each color appears in the two decks where they make the most sense:
White - Air and Fire
Blue - Water and Air
Black - Earth and Water
Red - Earth and Fire
Green - Earth and Air
Per the standard for major Commander product cycles, each deck introduces three new mythics, ten new rares, three new uncommons that are shared with at least one other deck in the cycle, and one new common that appears in all decks in the cycle. Thus, each of these four decklists has 17 Wastes included as placeholders.
Aerial Expertise's main theme is flying. Many of the creatures in this deck have flying, and many of the cards produce creature tokens with flying. Angels and Spirits are particularly common, with Birds, Thopters, and a number of one-offs appearing as well. There's also an enchantment subtheme, with enchantments that happen to play quite nicely with the flying theme.