Investigators suspect the Army helicopter crew that collided with an American Airlines jet near Washington, D.C., might have had inaccurate altitude readings and missed key air traffic controller instructions.

Black Hawk helicopter may not have heard order to go behind American Airlines jet - The Army helicopter appeared to be experiencing other issues with its communications and technology, according to sa

The National Transportation Safety Board says altimeter in the Black Hawk helicopter may have malfunctioned before the DCA mid-air collision with an American Airlines jet. All 67 people aboard died.