informed the head-end engineer, by radio, that the trailing units had cleared the siding. The helper engineer testified that his locomotive was in the eighth throttle notch (full throttle) before entering onto the mainline. The head-end engineer and the conductor were still on the lead unit, SP 8278, and the head-end brakeman remained on the third unit, SP 7549. The helper engineer and the helper brakeman were located in the trailing unit, SP 7443, of the helper consist. The helper engineer stated that the trip from Oban to Hiland (MP 463) was uneventful.
The Train Derailment
Testimony indicates that there was no communication between the head-end engineer and the helper engineer from the time Extra 7551 East left the siding at Oban until about 7:03 a.m. when the head-end engineer was cresting the hill at Hiland. The head-end engineer stated that he crested the hill at Hiland (MP 463) at 25 mph or 5 mph below the speed he believed was allowed based on the information he had about the train—6,151 trailing tonnage and four units (two head-end units and the two helper units) with full dynamic brakes and one head-end unit with intermittent dynamic brakes. As he crested the hill, the head-end engineer began using his dynamic brakes and initiated a 6-lb reduction of the air brake pipe pressure. He then asked the helper engineer if he had "…all of your dynamics…." The helper engineer responded, "Yeah, I'm in full." The head-end engineer testified that based on the helper engineer's response he believed that both helper units had operative dynamic brakes and had no reason to believe otherwise. He had not been informed by either the dispatcher or helper engineer that one of the helper units had inoperative dynamic brakes, and he did not inquire about the condition of the dynamic brakes on the trailing units. The helper engineer stated that he did not believe it was necessary for him to alert the head-end engineer of the status of the dynamic brakes on the helper unit because he (the helper engineer) believed the dispatcher would have already made that information known to the head-end engineer. The assistant chief dispatcher, who arranged for the helper unit to assist Extra 7551 East, testified, "I think the normal procedure would be for the helper engineer to relay that information to the road engineer, certainly not the train dispatcher." SP had no requirement that the dispatcher record or disseminate this information.
As the train continued descending the hill, the speed of the train increased to about 30 mph and the head-end engineer increased the brake pipe pressure reduction to 10 psi. According to the head-end engineer, the speed of the train held at 30 mph for a short time and then began to increase. He then increased the brake pipe pressure reduction to about 14 psi. He continued to increase the brake pipe pressure reduction gradually. Each time he reduced the brake pipe pressure, the train's speed would slow slightly and then it would begin to increase again. By the time he reached Canyon, he had reduced the brake pipe pressure a total of 18 psi, but the train was traveling at a speed of 31 mph and accelerating. The head-end engineer stated to Safety Board investigators, "As you're coming down Canyon [MP 469], there are a few places there where it [the train] will run on you, meaning that it's less curvy…you no longer had that resistance of the curves so the train will pick up a little speed, but I was compensating fine." As the