Investigators say deadly midair collision near Washington DC followed years of ignored traffic warnings

Crash that killed 67 was 100% preventable', says NTSB chair at hearing that addressed history of missed opportunities

National Transportation Safety Board members were deeply troubled on Tuesday over years of ignored warnings about helicopter traffic dangers and other problems, long before an American Airlines jet and an Army Black Hawk collided a year ago, killing 67 people near Washington DC.

The placement of a helicopter route in the approach path of Reagan national airport's secondary runway created a dangerous airspace and a lack of regular safety risk reviews made it worse, the board said. That was a key factor in the crash along with air traffic controllers' over reliance on asking helicopter pilots to avoid other aircraft.