Two small planes collided in midair over one of the runways on the outskirts of Tucson last week. One hit the ground and caught fire, sending up a plume of black smoke. The remains of two people were found in the charred wreckage. The other plane was able to land, with those occupants uninjured.

Tens of thousands of planes take off, land and perform touch-and-goes at the Marana Regional Airport in southern Arizona every year. Without an air traffic control tower, it's a calculated dance that requires communication by pilots.