An F-15 from the Massachusetts Air National Guard's 104th Fighter Wing taxis out for a morning sortie and an F-16 from the 18th Aggressor Squadron follows behind. The fighters and airmen are participating in the "Sentry Aloha" fighter training exercise at Joint Base Pearl Harbor-Hickam, Hawaii, Jan. 28, 2015. (Hawaii Air National Guard photo/Senior Airman Orlando Corpuz)