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.

Two U.S. senators called on Wednesday for increased funding and staffing for Federal Aviation Administration air traffic control after a fatal midair collision in the nation's capital last month highlighted the persistent lack of aviation safety personnel.

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.