That looks better every time I look at it, Tom. That runway looks like it could be made of inlaid wood. I could only suggest some black spires, more stone, or perhaps some riveted iron plate somewhere. And I would change the color of the orange buildings and control tower to redder brick, so that the brass stands out.
Here's a cobblestone texture I found that's easy to shape that you might find a use for:
View attachment 260306
You're Okay, I think, showing Zeppelins and Biplanes taking off and landing, as they're all available about the same time - okay, about 20 turns later than - Propeller Island in the
Third Era (British) and remain primary airships for the remainder of the game. The Hikaro units are 'king' units - only one for each Civ (if they've captured the parts), so I wouldn't use those as day-to-day aircraft.