Marines Sling-Load Humvee During Tactics Exercise U.S. Marine Corps 1st. Lt. William Frazier, right, briefs Marines in preparation for a sling-load operation during an assault support tactics exercise at Landing Zone Bull, Chocolate Mountain Aerial Gunnery Range, Calif., Oct. 12, 2015. Frazier is an assistant aircraft maintenance officer. U.S. Marine Corps photo by Cpl. Summer Dowding SHARE: Download: Full Size (0.7 MB) Tags: Photo Essays, Sling-Load Operations, U.S. Marine Corps, All images Credit: Marine Corps Cpl. Summer Dowding VIRIN: 151012-M-UU051-278.JPG Photo Gallery