Described is a system for adaptive calibration of a sensor of an inertial measurement unit. Following each sensor measurement, the system performs automatic calibration of a multi-axis sensor. A reliability of a current calibration is assessed. If the current calibration is reliable, then bias and scale factor values are updated according to the most recent sensor measurement, resulting in updatedbias and scale factor values. If the current calibration is not reliable, then previous bias and scale factor values are used. The system causes automatic calibration of the multi-axis sensor using either the updated or previous bias and scale factor values.