Black Hawk helicopter collision with passenger jet was part of a routine, annual re-training of night flights on a standard corridor for a continuity of government mission

 Crashed US Army Black Hawk unit was responsible for doomsday readiness

... The three soldiers killed in the collision were part of the 12th Aviation Battalion at Fort Belvoir in Virginia, whose responsibilities in a national crisis include evacuating Pentagon officials. Another 64 people were killed in the passenger plane. ...