A new investigation into the Washington, D.C., plane and helicopter collision over the Potomac River that killed 67 has blamed personnel failures of both the pilot and the air traffic controllers.

The crash on Jan. 29 occurred when a Black Hawk helicopter on a training mission collided with an American Airlines passenger jet carrying 64 people. Previous investigations have said the Black Hawk helicopter was flying above the permitted flight ceiling of 200 feet. The Black Hawk was flying at 300 feet at the time of the collision. It was also previously revealed that the Black Hawk did not have an advanced tracking system enabled, which would have allowed air traffic greater accuracy in its tracking of the Black Hawk’s path.