he determined the number of locomotive units that would be needed to move the train up the grade based on the 8,900 tons. He testified also that he had never previously recalculated the tonnage of a train to determine the number of locomotives that would be needed. He stated that he further believed that the crew had been provided with an upgraded weight reflecting the figure of 8,900 tons. He did not communicate with the crew nor did he use the computer system, which was available to him at his desk in Los Angeles, to determine the tonnage figure that had been provided to the crew.
After conducting an initial terminal air brake test, the crew of Extra 7551 East departed Mojave yard (MP 381.3) at 12:15 a.m., on May 12, en route to Fleta (MP 384.4) with a locomotive consisting of units SP 8278, SP 7551, SP 7549, and SP 9340 configured in that order from east to west. (The engineer testified that because he was not told to do anything with unit SP 7551, he kept it in the consist.) The engineer was operating from the lead unit, SP 8278, en route to Fleta. Because maintenance-of-way equipment was occupying the east end of the siding at Fleta, the dispatcher instructed the crew to continue eastward to Ansel (MP 390.4) and enter a side track at that location to clear the main track for traffic. According to the engineer, Extra 7551 East arrived at Ansel at 12:40 a.m., waited for the main track traffic to pass, and departed Ansel at 1:15 a.m. to return to Fleta. On the return trip to Fleta, SP 9340 was the lead unit in the consist, and the engineer operated from that unit. Because the maintenance-of-way equipment was still occupying the east end of the siding at Fleta, the crew was unable to position their locomotive units on the east end of the train to continue their eastbound trip. It was necessary, therefore, for the crew to enter the west end of the siding (see Figure 2), couple their units to that end of the 69 hopper cars, return westbound to Mojave yard, reposition their locomotives units at that location, and then continue their eastbound train movement. The engineer testified that before departing Fleta, the train line pressure was charged but an air brake test was not conducted. The engineer stated that while operating from unit SP 9340 on the return trip to Mojave, the dynamic brakes were intermittent: "It would load and then the dynamics would drop out on the unit." (Additional discussion occurs under Mechanical Information.) The engineer testified that after the locomotive consist was repositioned and coupled to the cars in Mojave yard, a test for leakage of the train line pressure and an initial terminal air brake test were performed. According to the engineer, none of the crewmembers expressed concern about the tests. After waiting for an inbound train to clear the main track, Extra 7551 East departed Mojave at about 3:35 a.m. with the engineer operating the train from the lead unit, SP 8278. The conductor was
- The SP air brake rules require that the train air brakes be tested before the train departs its initial terminal.
- Train designation is based on the number of the lead locomotive unit. Even though unit SP 8278 was the lead unit in the locomotive consist, the train designation remained Extra 7551 East.
- Dynamic braking is an electrical means used to convert some of the energy of a moving locomotive into an effective retarding force.