At McKinley Climatic Laboratory on Eglin Air Force Base in Florida, FTA-4 underwent extreme temperature tests between February 28 and March 17, 2017. After initial set up, temperatures sunk down to -40° C for five full days of extreme cold testing. Following this, the testing team removed their winter coats and swapped in their t-shirts, and ratcheted the heat up to 50° C for several more test days. Among other systems, the test and data gathered is used to validate the performance of the Environmental Control System (ECS). “Pull-Up” and “Pull-Down” tests, which begin in a cold or hot soaked condition, measured the ability of the system to control the cabin and flight deck to a comfortable temperature within a specified time.