At their closest points, helicopters and planes routinely flew within 75 feet near the airport, according to the NTSB.

In January, 67 people died when an American Airlines passenger flight crashed with a military helicopter near Washington, D.C.

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,