Pararescuemen of the US Air Force board an HH-60G during the Angel Thunder 2010 excercise at the forward operating Bisbee-Douglass airport, south of Tucson in southern Arizona, the United States, April 21, 2010. US Air Combat Command held the annual personnel recovery and combat search and rescue exercise, Angel Thunder 2010, from April 21 to 22 in the south Arizona desert. The exercise features a personnel recovery mission behind enemy lines, namely in Iraq and Afghanistan. Multinational air force members from Brazil, Canada, Chile, Colombia, France, Pakistan, etc., participated in the largest Department of Defense personnel recovery exercise. [Zhang Jun/Xinhua]