U.S. Air Force Staff Sgt. Chris Rundell, Heating Ventilation and Air Conditioning (HVAC) craftsman assigned to the 633rd Civil Engineer Squadron, analyzes an air flow controller system at Langley Air Force Base, Va., Jan. 5, 2016. As an HVAC craftsman, Rundell maintains electric, electronic and pneumatic controls in refrigeration and cooling equipment. (U.S. Air Force by Staff Sgt. J.D. Strong II)