Crashed US Army Black Hawk unit was responsible for doomsday readiness

The Black Hawk helicopter that collided with a passenger jet in Washington on Wednesday was on a training flight along a route core to a seldom-discussed military mission to evacuate senior officials to safety in the event of an attack on the U.S., officials say. The military mission, known as "continuity of government" and "continuity of operations," is meant to preserve the ability of the U.S. government to operate. Most days, crews like the one killed on Wednesday transport VIPs around Washin