U.S. Army AH-1 Cobra attack helicopters stand ready along a forward airstrip in South Vietnam, with CH-47 Chinook transport helicopters visible on the runway beyond. Rotary-wing aircraft such as these provided armed escort and heavy-lift support for covert cross-border reconnaissance operations conducted by MACV-SOG (Studies and Observations Group) forces during the Vietnam War, including the 1970 mission later known as Operation Tailwind. Project: 219426