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 NTSB hearing is patining a picture of a control tower that was understaffed and ill-equipped to handle the traffic if faces.

An air traffic controller should have warned an American Airlines Group Inc. jet that there was a US Army Black Hawk in the vicinity before the two craft collided midair near Washington in January, a Federal Aviation Administration official said.