On a recent morning when I stepped outside my house in Charlotte to walk the dog, I heard the hum of a propeller plane overhead. The sound of single-engine aircraft isn't unusual in the area at this time of year. Planes routinely fly to and from Burlington International Airport 18 miles away, and seaplanes fly over Lake Champlain. In addition, Shelburne Airport is eight miles to the north; Basin Harbor Airport in Vergennes, 16 miles to the south. Each of the turf airstrips averages about two dozen flights per week, according to AirNav.com, a website for pilots and aviation enthusiasts.