OVER HELMAND PROVINCE, Afghanistan – The Marine pilots peered closely at the ridgelines below, roaring through the sky in helicopters loaded with ordnance. “See that compound there?” one of them said Saturday, skimming over a desert plain in a UH-1Y Huey. “Let’s keep our eye on it.” The observation was part of a routine combat sustainment mission, which are conducted to keep the helos ready for war. They’re typically launched from the Marine flight line at Camp Bastion, a British base abutting Camp Leatherneck, the largest Marine installation in Afghanistan. A Sept. 14 attack on Bastion has brought a new…