An infrared sensitive lens mounted outside the helicopter “takes the temperature” of each heat pipe and transmits the reading to a video camera. The information is displayed on a video screen. The brighter the images appearing on the screen, the more heat is being radiated from the heat pipe. A mal-functioning heat pipe appears as a dark image., 1977-04, PCA0002-4b-26, Folder: PCA0002-4b. Alyeska Pipeline Service Company : Trans-Alaska Pipeline Construction Collection, 1976-1977, PCA 2. Alaska State Library - Historical Collections Finding Aids. https://alaska.libraryhost.com/repositories/2/archival_objects/17818 Accessed May 23, 2025.