A decision making process for evaluating performance shifts identified during a diagnostic trend analysis of gas turbine engine data includes first determining whether each performance shift is actionable, and then determining what maintenance action is required for actionable performance shifts. The electric machine includes, a housing defining an internal volume, a stationary shaft fixedly attached to the housing, a stationary field coil attached to the shaft, a pole assembly rotatable about the shaft, and a pulley fixedly attached to the pole assembly being positioned externally of the internal volume. A non-Blanchard reference altitude and a trajectory of the flying object are measured and input to a Kalman filter.