Plane collides with Blackhawk helicopter Washington DC

[Zaphod58]

I heard something about the plane being switched to another runway...but no link.  Seems odd?

Couldn't the collusion be anticipated on radar?

Changing runways is fairly common. They plan for a runway, but sometimes there's too much traffic, or someone doesn't clear soon enough so they change them to a different runway.

There was a collision alert but that airspace is usually pretty busy so it may not have been seen in time.