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,

Investigators so far have highlighted several factors that may have contributed to the collision, which left 67 people dead.

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.

The Army goggles would have made it difficult to see the plane's colored lights, which might have helped the Black Hawk determine the plane's direction. The goggles also limited the pilots' peripheral vision as they flew near Ronald Reagan Washington National Airport.

The NTSB revealed that the Black Hawk helicopter may not have known its true altitude at a hearing. Mom Worried If New Rescue Dog Had ‘Bonded’ With Baby, Then She Caught Them Forensics expert analysis of Jeffrey Epstein jail video contradicts government's claims We Asked Young Men Who Voted For Trump to Grade Him.

The National Transportation Safety Board on Thursday questioned the failure of an air traffic controller to issue a warning about a potential collision in the moments before a crash between an Army helicopter and an American Airlines regional jet that killed 67 people.