Early that morning an unusually long and heavy freight train developed problems (unofficially a hot box) whilst traveling west from Ogden. This required First 21, the first section of the Pacific Limited comprising 18 cars headed by SP GS-3 No. 4425, to stop and then proceed with caution. Second 21, the second section comprising 20 cars headed by SP Mt-4 No. 4361, apparently unaware of the problems ahead, continued at full speed.
