The NTSB continued its hearings Thursday into the deadly air collision between a military aircraft and a passenger jet.

During the hearings, the NTSB was told that the Army helicopter never heard the command from the air traffic controller to "pass behind the CRJ" as the transmission was stepped on. It was also revealed that the plane's pilots were not warned by the controller that there was a helicopter nearby or cleared to fly near the helicopter.

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

Authorities are investigating after one person died and two others were injured when a small plane crashed into a remote section of Olympic National Park in Washington.

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 National Transportation Safety Board will wrap up its public testimony about the fatal midair crash between an Army helicopter and a commercial jet.