How an Army Black Hawk helicopter collided into an American Airlines jetliner in a deadly crash over the Potomac River Wednesday night is still unknown, but questions are emerging, including the altitude of the military helicopter.

U.S. President Donald Trump said on Friday the Army Black Hawk helicopter that collided with a regional passenger jet in Washington, D.C. was flying too high at the time of the accident, in what appeared to be a major disclosure about the investigation.