Sometimes, the FCAB is coupling two trains together to climb the Cumbre pass from Mejillones. First part is with 27 sulphuric acid tank cars with 3 locomotives, second part with locomotives GR12U # 1403 and GR22C # 1435 (former WAGR AA #1518, built by Clyde in 1967) and empty platform cars for copper transport. This is not distributed power, the locomotives are controlled by an engineer.
