The National Transportation Safety Board said the helicopter’s cockpit voice recorder didn’t capture key directions from air-traffic control and is investigating whether the crew might have seen a different altitude on the flight instruments.

A Black Hawk helicopter crew may not have heard key instructions from air traffic control before it struck an American Airlines jet near Washington DC a fortnight ago, according to black box data.

Black Hawk pilots may not have heard a critical directive from air traffic control to fly behind the American Airlines plane in the seconds before it collided with the jet, the National Transportation Safety Board said Friday.

The crew of the helicopter that collided midair with an American Airlines jet near Washington D.C.’s Ronald Reagan National Airport might not have heard instructions from the air traffic controller to pass behind the plane,