Member Earl F. Weener filed the following concurring statement on May 24, 2016.
I concur with the findings and recommendations in this report generally. However, I think that an insufficient emphasis was placed on several circumstances that, if not contributing factors, created an environment with great potential for an accident and greatly diminished NTSB's ability to determine the actual cause of this accident with certainty.
When the NTSB investigates an accident, the result is a finding of probable cause. In some accidents, the probable cause is clear and certain. In some accidents, the nature of the evidence recovered during the investigation limits the determination to the literal meaning of the word probable. So it is with the derailment of Amtrak 188. We were able to determine that no track or train malfunction caused the accident. That left investigators with the actions of the engineer having caused the excessive speed as the train entered the curve at the accident site. Because no inward-facing camera had been installed in this locomotive, however, it is impossible to say with certainty what happened inside that locomotive or what, in fact, caused the engineer to lose awareness to the extent that he failed to reduce the train's speed in time for the curve.
It is very disturbing that so much rests on the ability of an engineer, working alone for extended periods of time, to determine his or her location based not on clear visual markers, but on memory. The engineer must do this in many instances without the assistance of GPS driven, two-dimensional map display and guidance. While memory training may prove to be of some benefit when studied in the future, the reality is that intervening events are likely. In this accident, for example, the engineer explained to NTSB investigators that the rock throwing incident on the SEPTA train was a fairly common occurrence. Until each train can be equipped with an active navigational display, an engineer could be required to use a checklist to keep track of his or her location as stops or landmarks are passed. The use of checklists has been extremely successful in aviation to reduce the type of diverted attention or prospective memory error that may have been the root of this accident.
Investigators looked at what evidence they did have and theorized that the engineer must have lost track of where he was on his route and that this must have been due to his attention being focused on the emergency situation on the SEPTA train. While this is a reasonable possibility, acceptance of that theory requires the dismissal of a portion of the engineer's statement in which he stated that he did know where he was shortly before approaching the curve. This is troubling given that much of our probable cause is based on that same engineer's statement. Again, without a recording of his actions inside the locomotive, the engineer's statement is the best evidence of his experience. The reality is that exactly what happened that night will never be known.
What is obvious, however, is that something did cause the engineer to fail to properly control the speed of the train. There is no doubt that an alert, well trained, healthy operator is the most important safeguard in any mode of transportation, but humans are inherently fallible. Even with the best training, medical screening, and hours of service prohibitions, anything from an undiagnosed medical condition to a poor night's sleep to some external stress can result in a temporary, partial or complete loss of awareness or even consciousness. Such occurrences are eventualities, not mere possibilities. This is why I understand the vice chairman's vigorous
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