The following video of air traffic around Reagan National captures a near miss between a commercial aircraft (Republic Airways 4514) on final approach with an Army helicopter just 24 hours and 40 minutes before the collision between an Army helicopter and American Airlines regional jet.

Note at 00:54 on the tape, the air traffic controller states:

Additional traffic is gonna be a helicopter over Memorial Bridge, VFR [Visual Flight Rules] northwest bound at 200 feet. Maintain visual separation as they continue up the river.

At 2:14, the pilot of the approaching commercial aircraft (Republic Airlines 4514) states:

Tower, Brickyard 4514 is on River Visual 19.

The controller replies:

Brickyard 4514, Washington Tower, reduce to final approach speed, runway 19 cleared to land. … Additional traffic is a helicopter northbound over Georgetown, northbound, 300 feet.

The helicopter holds his course along the river. Why does he climb to 300 feet?

The critical time period begins at 2:30 on the tape as the helicopter (call sign PAT 11) steers along the river, on a northwest heading, and onto a collision course with the southeast bound approaching commercial jet (RPA 4514).

At 3:12 on the tape we see the two aircraft converge.

At 3:36, RPA 4514 states:

And Tower, we had an RA [Resolution Advisory]. Brickyard 4514 is going around.

Note that a TCAS Resolution Advisory—prompting an evasive maneuver and a go around—on the final approach to a busy airport is a major safety event.

It appears that the helicopter call sign PAT 11 apparently means Priority Air Transport 11, indicating the helicopter is used for transporting important persons. The helicopter that collided with the AA CRJ the next day had call sign PAT 25.

Finally, note that helicopters are FAR MORE maneuverable than commercial jets are, especially when the latter are on final approach, when their pilots must concentrate on lining up with the runway and maintaining the proper glide slope.

It seems to me the FAA should to tell Army PAT helicopters to stay far away from the final approach path to airports dedicated primarily to civilian fixed wing aircraft.