They were flying Helicopter Route 4 and at that point of the route they had Anacostia to the east and Reagan National to the west. It is reported that the collision occurred at 400 feet. This is what is being reported. Now, at that point they should have been no higher than 200 feet. and they should have stayed closer to the east bank of the river. Also, the fight path reported shows that they start to go west (right). Why?
I was assigned to that airfield a long time ago with duty at Ft. Meade. The helicopter routes are basically the same. I was not a pilot but a crewmember and did some navigating. I flew those routes almost on a daily basis.
Here is link. The map you are looking for is the smaller one on the bottom: