Alfred Gregg, an instrumentation, data and controls engineer at arc heaters on Arnold Air Force Base, and other engineers work on a troubleshooting exercise during a class April 18 at University of Tennessee Space Institute on programming and troubleshooting General Electric programmable logic controllers. Test Operations and Sustainment contractor, National Aerospace Solutions provided the week-long technical training course aimed at new instrumentation, data and controls engineers. PLCs are used for process control automation in many industries, said Curtis Walters, a NAS-nLogic supervisor in the Control Solutions Section. (U.S. Air Force photo by Jill Pickett)