At Fort Belvoir, an army base 12 miles south of the Pentagon, Lt. Col. Mark R. Lindon is conducting a “garrison control exercise” when the 9/11 attacks begin. The object of this exercise is to “test the security at the base in case of a terrorist attack.” Lindon later says, “I was out checking on the exercise and heard about the World Trade Center on my car radio. As soon as it was established that this was no accident, we went to a complete security mode.” Staff Sgt. Mark Williams of the Military District of Washington Engineer Company at Fort Belvoir also later says: “Ironically, we were conducting classes about rescue techniques when we were told of the planes hitting the World Trade Center.” Williams’ team is one of the first response groups to arrive at the site of the Pentagon crash and one of the first to enter the building following the attack. [Connection Newspapers, 9/5/2002] A previous MASCAL (mass casualty) training exercise was held at Fort Belvoir a little over two months earlier (see June 29, 2001). It was “designed to enhance the first ready response in dealing with the effects of a terrorist incident involving an explosion.” [MDW News Service, 7/5/2001] Located at Fort Belvoir is Davison Army Airfield, from where UH-1 “Huey” and UH-60 Black Hawk helicopters fly. Davison’s mission includes maintaining “a readiness posture in support of contingency plans,” and providing “aviation support for the White House, US government officials, Department of Defense, Department of the Army, and other government agencies.” [Pentagram, 5/7/1999; Military District of Washington, 8/2000]