The problem started when the primary electrical system failed. Sixty-eight people were trapped in the air aboard two red-and-white gondolas. Sunset was still three hours off. The tramway's supervisor of operations drove in from Westchester to get it going again. When that proved impossible, he turned on a diesel-powered hydraulic backup with just enough power to pull the gondolas back to shore. For a moment, it worked: the gondolas moved. But then the hydraulic backup failed, too. The supervisor, Armando Cordova, was out of options — beyond talking to the engineers at the European company that built the tramway and...