U.S. Army Chief Warrant Officer 2 Jordan Frizzell, 7th Battalion, 158th Aviation Regiment, conducts startup procedures on a UH-60 Black Hawk before a medical evacuation mission during Exercise Vibrant Response at Camp Atterbury, Ind., Aug. 22, 2011. Vibrant Response is the largest chemical, biological, radiological and nuclear response exercise designed to prepare expeditionary units focused on responding to domestic CBRN incidents.