Alexi Horowitz-Ghazi

On a recent sunny afternoon at a solar farm outside Philadelphia, Pa., commercial drone pilots Tony Zimlich and Gunner Goldie are preparing for flight.

Dressed in hard hats and matching yellow vests, they run through a series of safety and equipment checks, and survey the surrounding terrain and airspace, before picking up what looks like a pair of oversized video game controllers. Then, with a streak of beeps and whirs, their drone — about the size of a milk crate — rises steadily into the sky above.