11th Civil Engineer Squadron firefighters use a chainsaw to cut plywood for a flashover identification trainer Aug. 28, 2012 at Joint Base Andrews, Md. A flashover is the near-simultaneous ignition of most of the directly exposed combustible material in an enclosed area. At Flashover identification training, firefighters learn the life-saving skill of recognizing the indicators of flashover. (U.S. Air Force Photo by Senior Airman Perry Aston)