Patrick Hempen, the now-retired Federal Aviation Administration director of aviation accident investigations, gave some insight on what may have caused an American Airlines regional jet and Black Hawk helicopter to collide midair Wednesday.

An American Airlines plane carrying 60 passengers and four crew members collided with an Army Black Hawk helicopter outside Reagan National Airport near Washington, D.C. Wednesday evening. Three soldiers were onboard the helicopter and a massive search and rescue operation is now unfolding in the Potomac River.

A regional American Airlines passenger jet and a Black Hawk military helicopter collided over Washington, D.C., on Wednesday night in the nation's first major commercial airline crash since 2009. There are confirmed fatalities from the collision,