U.S. Air Force Capts. Vincent Levraea (left) and Jason Steinlicht, both pilots from the 317th Airlift Group at Dyess Air Force Base, Texas, conduct pre-flight checklists at Léopold Sédar Senghor International Airport in Dakar, Senegal, Nov. 4, 2014. The pilots are preparing to fly a sortie into Monrovia, Liberia, to deliver more than 8 tons of humanitarian aid and military supplies in support of Operation United Assistance, the U.S. Agency for International Development-led, whole-of-government effort to contain the Ebola virus outbreak in West Africa. (U.S. Air National Guard photo by Maj. Dale Greer/Released)