Do more U.S. airports need control towers? That's one of the questions that has arisen following a midair collision at an airport in southern Arizona last week.

At least two people killed Wednesday during an "aircraft collision" at a southern Arizona airport, according to authorities.

The crash at the Marana Regional Airport, about 21 miles northwest of Tucson, is the second fatal aviation mishap this month in Arizona.

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.