Airmen Aniel Rios and Mason Urland, 365th Training Squadron heavy avionics flight course students, perform fault isolation on an instrument landing system at Sheppard Air Force Base, Texas, August 9, 2018. It is extremely important for Airmen to be able to trouble shoot an ILS as it is the system which enables pilots to conduct a landing approach if they are unable to establish visual contact with the runway. (U.S. Air Force photo by Airman Madeleine E. Remillard)