According to this report:
Who Was Black Hawk Helicopter Pilot in DC Plane Crash? What We Know - Newsweek
All 3 people in the Black Hawk were pilots? 2 with "hundreds of hours" and 1 with "over 1000 hours"?
How could 3 qualified pilots, all in communication with each other, not properly identify an airplane in the air? There was another similar airplane in the air space and on the approach, but for all 3 to make the same mistake?