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 have found that a helicopter involved in a deadly crash with a passenger plane over Washington was flying above its height limit. The helicopter's altitude-measuring instrument was also inaccurate.

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.