Capt. Charles Kirchner, F-16 Fighting Falcon pilot assigned to the 121st Fighter Squadron, District of Columbia Air National Guard, performs preflight checks prior to departing for a mission during exercise Green Flag 21-06 at Nellis Air Force Base, Nev., April 15, 2021. Green Flag provides combat training to joint and coalition warfighters in air-land integration and the joint employment of airpower in support of the U.S. Army’s National Training Center. (U.S. Air Force photo by Airman First Class Zachary Rufus)