Reliability engineering tip of the week: As a former control systems engineer, historian (e.g. PI) data is a great first place to look when conducting Root Cause Analyses (RCAs) or investigations. Use trends and log files to help establish an evidence-based timeline or sequence of events. There are too many times when I’ve had an operator say that: “We didn’t push the stop button”, when the control log says the stop command was initiated from their workstation.