NYT
The Army Black Hawk helicopter was supposed to be flying in a different location and lower to the ground as it traversed the busy Reagan National airspace, the people said.
Before a helicopter can enter any busy commercial airspace, it must get the approval of an air traffic controller. In this case, the pilot of the helicopter asked the air traffic controller for permission to use a specific, predetermined route that lets helicopters fly no higher than 200 feet and that hugs the bank on the east side of the Potomac River, a location that would have let it avoid the American Airlines plane.
The requested route — referred to as Route 4 at Reagan — followed a specifically carved out path already known to the air traffic controller and helicopter pilot. The helicopter pilot confirmed visual sight of the American Airlines plane, and the air traffic controller instructed the helicopter pilot to follow the route and go behind the plane.
But the helicopter pilot did not follow the intended route, the people briefed on the matter said.
Rather, the helicopter was above 300 feet, not below 200 feet, and was at least a half-mile off the approved route when it collided with the jet.
A senior Army official urged caution in making any assessments until the helicopter’s black box could be recovered and analyzed, along with other forensic data.
The official, who spoke on condition of anonymity because of the ongoing inquiry, said the Black Hawk’s pilots had flown this route before, and were well aware of the altitude restrictions and tight air corridor they were permitted to fly in near the airport.
http://www.nytimes.com/live/2025/01/29/us/plane-crash-washington-dc#black-hawk-helicopter-plane-crash