Well if K.O'd already (0hp) all fall damage would be reduced to 1 failed death save. LolHmm. Perhaps the Aarakocra as a race choice. Simply because, unlike a typical ground-based PC stumbling over and falling to the ground, being stunned/KO'd or the like whilst flying can typical end a character through falling damage, at least at early levels.
...and in my experience, a player that chooses a flying race is gonna fly! Fly high!
Sure you can explain the dangers before hand though it tends to be one of those learning curves that starts with a second, less splatted, character.