The National Transportation Safety Board questioned witnesses Friday on collision avoidance technology and organizational systems to manage risk. It is the third and final day of investigative hearings probing January’s midair collision between a US Army Black Hawk helicopter and an American Airlines regional jet,

The board focused on air traffic control and heard it was common for pilots to ask to use visual separation — relying on eyesight — just as the Army Black Hawk's pilot agreed to do the night of the crash.

A three-day hearing into the January mid-air collision between an Army Blackhawk helicopter and an American Airlines jet concluded today. The National Transportation Safety Board's hearing focused on the breakdown of safety systems that led to the deaths of 67 people,

The goggles also limited the pilots' peripheral vision as they flew near Ronald Reagan Washington National Airport.