Ralph Thompson stands near our 3/4 ton FDC truck which is outfitted to work as a mobile fire direction control center. The radios sit on platforms behind the seat and are powered by the truck’s electrical system. This system did not work during the rainy season of 5 or 6 months; keeping electrical equipment dry and working was impossible outdoors.
Two people kept independent charts so we were unlikely to compute incorrect settings. When our FADAC was working we used it as the back-up, rather than working a second chart. Pushing pins into the charting table was not precise and the FADAC eliminated errors caused by pin misplacement. Laser range finders used by forward observers were just beginning to be used at the end of my tour in August 1969. They reduced distance measurement errors. Read the full story. https://vietnamsoldier.com/accurate-artillery-fire-2/