U.S. Air Force Tech. Sgt. Dave Johnson, a student attending the Engineering Installation vehicle training class, operates a Cat excavator Dec. 13, 2017, at the Air National Guard Schoolhouse, Fort Indiantown Gap, Pennsylvania. Johnson waited for a signal from the Airman in the foreground before hoisting a maintenance hole with the excavator. (U.S. Air National Guard photo by Staff Sgt. Tony Harp/Released)